Histology- Exam # 3 Flashcards
What is the black arrow pointing at? What is the blue arrow pointing at?
Black Arrow: Cortex
Blue Arrow: Medulla
What is the function of the female reproductive tract?
- Production and transportation of oocyte
- Transportation of spermatozoa and fertilization
- Accommodation of the fetus until birth
What is the surface epithelium of the ovaries composed of?
Simple cuboidal/ squamous (germinal epithelium)
What is the purpose of the cortex and important structures? What about the medulla?
- The cortex is the peripheral aspect of ovary, and the purpose is to house follicles (at different stages of maturation)
- Stroma (spindle shaped cells are also present)
- The medulla is the central aspect of ovary and is made of loose connective tissue and is highly vascular
In this section of ovarian tissue. What is the blue arrow pointing at ? What is it made of? What is the black arrow pointing at? What is it made of?
Blue arrow: Tunica albuginea: this is made of dense connective tissue.
Black arrow: Surface epithelium (mesothelium, Germinal epithelium) and is simple cuboidal/ squamous.
What tumors can arise from mesothelium? Where?
Mesothelioma. Oral cavity
What hormones influence the estrous cycle?
Follicle Stimulating Hormone, Lutenizing hormone, Estrogen and Progesterone.
What secretes Follicle stimulating hormone and lutenizing hormone?
Pituitary gland.
What secretes estrogen and progesterone?
Cells within the follicles
Which stage of follicle is the one that is involved in ovulation?
Tertiary or Antral Follicle
How many oocytes are ovulated per heat cycle in each animal species?
Horses: 1
Ruminants: 2
Sheep: 3
Cats/ Dogs/ Pigs : multiples of oocytes
Dogs can ovulate on different days (can have different fathers in the same litter)
Which stage of follicular development is this?
Tertiary/ Antral Follicle
Which stage of follicular development is this?
Primary Follicle
Which stage of follicular development is this?
Primordial Follicle
Which stage of follicular development is this?
Secondary Follicle
What occurs between the primordial follicle and primary follicle?
Oocyte enlarges and the follicular cells divide and become cuboidal (single or double layer)
Name the layers of the follicle. What stage of development is this follicle in?
A.) Stroma Cells
B.) Theca Cell Layer ( secretes androgens that are converted into estrogen by granulosa cells)
C.) Zona Pellucida ( layer of glycoprotiens between the oocyte and granulosa cells)
D.) Granulosa Cell Layer (Secretes estrogen in response to follicle stimulating hormone.
This follicle is a secondary follicle .
What is the outermost layer in the secondary follicle?
Theca cell layer
Stroma is the layer between follicles not part of follicle itself
Name the labeled parts. What stage of development is this in?
A.) Granulosa Cell Layer
B.) Cumulus oophorus (secretes hyaluronic acid, in order to facillitate penetration by spermatozoa)
C.) Zona Pellucida
D.) Corona Radiata (provides nutrients to oocytes)
E.) Antrum ( follicular fluid, provides nourishment for oocyte development)
F.) Theca interna
G.) Theca externa
H. ) Overall Theca cell layer.
What is the Theca interna layer and what does it secrete? Theca externa?
Theca interna: This is the inner Theca layer and secretes androgens that are converted to estrogen by granulosa cells,
Theca externa: Outer more fibrous layer
What is corpus hemorrhagicum? What causes it?
Temporary structure formed immediately after ovulation from the tertiary follicle. As the tertiary follicle collapses it is filled with blood that quickly clots.
What is the corpus luteum?
Granulosa and theca cells differentiate into lutein cells ( have abundant eosinophillic granular cytoplasm). Progesterone is secreted to prepare the uterus for pregnancy
What is the area called around the black box?
Corpus luteum
What happens to the corpus luteum if pregnancy does not occur?
Corpes luteum becomes corpus albicans and the degenerated lutein cells are replaced by fiborous connective tissue.
Shown by red arrow
What hormones are produced by Theca interna?
Androgens ) induced by lutenizing hormones.
What is the pathway of androgens?
- ) Produced by theca interna ( induced by lutenizing hormone)
- ) After being released they are absorbed by granulosa cells
- ) they are then converted into estrogens ( estradiol)
What hormones do granulosa cells produce ( other than their interactions with androgens)?
Inhibin and follicostatin
Label the parts of the oviduct and give any important information.
A.) Infundibulum- free opening wnd with fimbriae projections.
B.) Isthmus- narrowed portion to connect to uterus.
C.) Ampulla - where fertilization takes place.
What is the structure of the oviduct?
- ) Mucosa- longitudinal folds projecting into lumen with simple columnar epithelium (cilliated). This is supported by lamina propria as inner layer of folds.
- ) Muscularis: Inner layer or spiral layer and outer longitudinal layer whose peristaltic contractions help propel oveum or fertilized zygote to the uterus.
- ) Serosa: Simple cuboidal/ squamous epithelium ( or mesothelium) supported by thin layer of connective tissue
Label each of the colored arrows of the histological section of oviduct
Yellow Arrow: Circular layer (muscularis)
Black Arrow: Longitudinal layer (muscularis)
Blue Arrow: Lamina Propria
Green Arrow: Cilliated columnar epithelium (mucosal cells)
What are the three regions that make up the structure of the uterus?
Endometrium
Myometrium
Perimetrium
What kind of epithelium is present in the endometrium and how does it differ between species?
In ruminants and sow you will see pseudostratified columnar epithelium, while in carnivores you will see simple columnar.
How can you identify the basal endometrial layer from the other layers?
The basal layer has alot of glands
What is the function of the cervix?
- provides physical barrier to uterus during pregnancy to protect fetus from ascending infection
- mucus secretion (uterine lubrication/ microbial clearence)
- Physical interdigitation of folds ( avoids ascending infections)
What is the difference in lining of cervix of dogs?
In other species it is lined by simple columnar cilliated epithelium with goblet cells. In dogs it is stratified squamous.
What is the function of the vagina?
- Fibromuscular tube that connects uterus to opening of external genitalia.
- copulatory organ for mating and birth canal during partuition
- highly acidic environment functions to prevent infection.
What epithelium is the vagina lined by?
Stratified squamous epithelium
TRUE OR FALSE: The type of epithelium that lines the vagina differs among domestic species?
FALSE: It is the same across all domestic species.
What is the function of the mammary gland and what kind of gland is it?
Function: Nourish neonate
- Food source: provides fat, protien, sugar, vitamins, water, and minerals
- Protection: Gives off immunoglobulins via colostum (IgG)
Is an Exocrine gland (specifically an apocrine(lipids) gland/ and merocrine (protiens)
- Morphology changes under hormonal influence
What is the difference in the structure of mammary glands during lactating and non lactating periods?
Lactating period: Acini predominate, simple cuboidal epithelium/ myoepithelium.
Secretion of milk via merocrine glands
Non lactating: connective tissue, few secretory acini
Which of these mammary glands ( Left or Right) is from a non lactating time period?
Right
Which histological section of tissue is a lactating mammary gland and why?
Left is from lactating mammary gland. This has more acini, while opposite side is mostly connective tissue which is typical for non lacting mammary glands.
What is the functions of the male reproductive system?
- Production/ transport of spermatozoa and other secretory products ( epididymal fluid and seminal plasma)
- Productio of hormones (testosterone inhibin, estrogen)
What is the structural units of the male reproductive system? What are eaches function?
- Testes(Produce spermatozoa, and hormone)
- Epididymis (transport and maturation of spermatozoa)
- Ductus defernes ( part of spermatic cord; transport of spermatozoa)
- Accessory sex glands ( produce seminal plasma)
Penis
What are the accessory sex glands? What do they produce?
- ampulla
- seminal vesicles (vesicular gland)
- prostate
- bulbourethral
They produce seminal plasma which contains glycoprotiens and nutrients for spermatozoa.
What is a male reproductive structural unit found specifically in ruminants?
Sigmoid flexus
TRUE OR FALSE: The prostate in Bovines is very large.
FALSE: Prostate is rather small and is not the characteristic lobed shape.
The testes are what kind of organ? Exocrine or endocrine?
It is both exocrine ( compound coiled, tubular gland) producing spermatozoa, and endocrine gland secreting hormones
What is the name of the fibrous white capsule of dense connective tissye that contains blood vessels ? What is the name of the layere of peritoneum that is tightly adhered to this layer?
- ) Tunica Albuginea
- ) Tunica vaginalis
What is the name of the interstitial cells of the testes?
Leydig cells
What occurs in the mediastinum of the testes?
Seminiferous tubules converge and sperm exits testis. Composed of straight tubules - Rete testis.
What are the cells that compose the seminiferous tubules? What is their roles?
Sertoli Cells- large columnar cells that extend the full thickness of the germinal epithelium
- Support the developing spermatogenic cells
- Establish blood testis barrier.
- Act as phagocytes, consuming residual cytoplasm during spermatogenesis.
- Convert testosterone to estrogen.
Spermatogenic cells
What is the order of development of spermatozoa?
Spermatogonia –> Primary spermatocytes–> Secondary spermatocytes (not ID) —> Spermatids ( early/ late) —> Spermatozoa
What is the function of the leydig cells?
Produce testosterone stimulated by lutenizing hormone.
What is the efferent ductules?
Portion that connects the rete testis with the proximal portion of the epididymis.
Do canines have seminal vesicles, bulbourethral glands, and ampulla?
No (only prostate)
What accessory sex gland is missing in Tom cats?
Seminal Vesicles
What accessory sex gland is missing in boars?
Ampulla
What is the difference in prostate in boar/ruminants vs. stallions and carnivores?
Ruminants/ Boars: Disseminated glandular tissue (within submucosa of pelvic urethra)
Stallion and Carnivores: Compact (encapsulated/ lobulated)
What is the name of the concretions of prostatic fluid in lumen of some glands in older animals? What does it look like?
Corpora Amylacea - it stains dark purple (Basophillic)
What are the two types of penis? Where is each typically found?
Fibroelastic: Bull, Boar, Ram
- large ammounts of connective tissue and elastic fibers but limited erectile tissue. Contains sigmoid flexure (ruminants)
Erection only includes increased length, no increased diameter. Most increase in peline length is due to straightening of sigmoid flexure.
Musculovascular (Man, Stallion, Dog, Tomcat)
- Alot of erectile tissue and little connective tissue ( lengthening and diameter increase during irrection)
What is bone marrow?
Mesenchymal-derived tissue that consists of hematopoietic cellular elements and a
complex microenvironment
What kind of bone marrow is their and what is the distribution?
Red/Active Marrow: Long bones rich in hematopoietic tissue ( ~ 100% at birth)- young animals. Found in flat bones in adults.
Yellow Marrow: Red marrow is gradually replaced with adipose tissue as animal age.
Marrow can change to 75% yellow marrow and 25 % red marrow as an adult.
What are the typical indications for bone marrow sampling? Where is the sample taken?
Indications:
FUO (Fever unknown origin)
Unexplained high/ low # cells (RBCs, WBCs,) platelets, on CBC
Investigation of possible cancer cells / infectious organisms
Sampling locations:
- Small animals: Proximal humerous/ femur
Large animals: Ventral sternum or ribs
Illiac crest can also be used.
What are the main components of bone marrow?
- ) Vascular- Veins, arteries, sinuses
- ) Support cells: Macrophages, endothelial cells, adipocytes, adventitial reticular cells
- ) Hematopoietic stem cells and prodgeny
- ) Trabecular bone ( osteoblasts/ osteoclasts)
What is the venous drainage pathway? (Bone Marrow)
From marrow sinusoids into large dialated central vein. Then from there into nutrient veins, and then back into systemic circulation
What three cells produce components of ECM of bone marrow for stuctural support?
- Collagen fibers
- Basement membranes of vessels and vascular sinuses
- Proteoglycans and glycoprotiens.
* ECM also aids in binding of hematopoietic cells for optimal cell proliferation and differentiation. Can produce cytokines that drive hematopoiesis.
What kind of cells are hematopoietic stem cells?
Multipotent ( can produce many different cells)
Need special stains ICC/IHC for cell surface antigens to identify specific stem cells in bone marrow samples.
Antigens change with each developmental stage of the cell,.
What are general trends in erythropoeisis?
- cells get smaller
- nucleus gets smaller
- nuclear material gets more condensed.
- cytoplasm becomes less basophilic and more red as hemoglobin content increases.
What is the stages of erythropoiesis?
CFU-E —-> Rubriblast —–> Prorubricyte —-> Basophillic Rubricyte —–> Polychromic Rubricyte—-> Metarubricyte —-> Reticulocyte —–> Erythrocyte
Rubriblast —-> Reticulocyte takes 3-5 days
Reticulocyte released into circulation —> Mature erythrocyte takes 1-2 more days)
If a dog presents to you in the clinic and you discover low red blood cells
(anemia) on a CBC, how long do you need to wait to draw your next sample to see if
the bone marrow has regenerated RBCs?
about 1 week
What is included in an erythroblastic island and what is the macrophages function?
- Central macrophage surrounded by erythroid precursor cells. Macrophage provides erythropoietin and iron to developing erythroid cells.
Located close to vessels.
What is a myeloblast?
The myeloblast is the first recognizable myeloid cell in the bone marrow
CFU-N, CFU-Eo, CFU-Bas are myeloblasts.
What is the order of Neutrophillic granulopoiesis?
CFU-GM —-> Myeloblast —-> Promyelocyte —-> Neutrophillic Myelocyte (secondary granules are present) —–> Neutrophollic metamyelocyte —–> Neutrophillic band —-> Segmented neutrophil.
What is the order of monocytopoiesis?
Multipotent hematopoietic stem cell —-> Common myeloid progenitor—– > Granulocyte- monocyte progenitor —-> Monoblast —-> Promonocyte —-> monocyte—-> Macrophage.
What is the cell that is involved in creating NK cells, T helper, and T suppressor cells? Where is this developed?
CFU-TL (Developed in thymus)
What is the cell that is involved in creating B cells and then eventually plasma cells? Where is this developed?
CFU-BL ( Developed in Bone marrow (bursa in birds))
Where to platelets come from? What drives differentiation and development into platelets?
Megakaryocytes
Primarily driven by Thrombopoietin, and is Produced primarily in liver, expression is upregulated by IL-6
What are negative regulators of hematopoiesis?
TNF-a
INF-g
TGF-b
Lactoferrin
What is the classifications of the lymphatic organs?
Primary (central lymphatic organs): Sites of development: Thymus, Bone marrow, Bursa of fabricus ( birds)
Secondary peripheral lymphatic organs : Sites where lymphocytes are activated and respond to antigens ( Lymph nodes, spleen, tonsils, Bone marrow)
What are secondary lymphoid organs found in ruminants but not other animal species?
hemal nodes.
Defense against blood-borne pathogens • Occur along blood vessels in the sublumbar area along
vena cava and abdominal aorta
What is the function of the thymus?
Processes stem cells from the bone marrow so that they acquire surface receptors to become T-lymphocyte
What is the histological appearence of the thymus?
Lobules seen from low mag.
- Components: Cortex (darker outer staining), Medulla( center, lighter staining)
- Medulla contains epithelial reticular cells that coalesce to form thymic hassals corpuscles (red centers)
What is the reason for corpuscles?
Corpuscles produce polypeptides to promote processing of
lymphocytes
• Corpuscles also surround capillaries in the cortex to protect
developing lymphocytes from blood-borne antigens
What happens to the thymus as the animal ages?
The thymus will decrease in size and its composition will change to mostly fat.
What are myoid cells, where can you find them/ what do they look like?
Can be found in avian thymus. Looks almost like muscle with striations and central nucleus.
What is a difference between avian and carnivore thymus?
Avians have vascular sinus’
What is the other name for the Bursa of Fabricius? When does it reach its maximum size, and what happens when it does?
Cloacal bursa. ( Round out pouching of caudodorsal aspect of cloaca) Reaches max size at 6 weeks of age, and then involutes
What is the histological appearence of Bursa of Fabricius?
- follicles with a dark cortex and lighter
medulla composed of B-lymphocytes •
Follicles also contain superficial layer of undifferentiated epithelial
cells
• Follicles arranged into crypt-like mucosal folds (called plicae)
lined by a layer of pseudostratified columnar epithelium
• Folds surround a lumen that opens into the proctodeum – most
distal chamber of the avian cloaca
What are lymph nodes, and what is their role in the body? What species does not have lymph nodes?
Filter lymph before it is returned to the
blood
The only lymphatic organs with both afferent and efferent lymph vessels
-Not found in most avian species (diffuse lymphatic tissue/ lymphatic nodules instead)
What is the histological appearence of lymph nodes?
Capsule: connective tissue/ smooth muscle/ elastic fibers (parts of capsule extend inward as trabeculae.
Cortex: Outer, distinct lymphatic nodules/ follicles containing B lymphocytes.
- Corona- Darker elliptical cuff of nodule
- Germinal center: lighter center (b cells proliferate, differentiate, and mutate here)
Medulla: Medullary cords- extensions of cortex into medulla. (Medullary sinuses)
What is the spleen and what is its stucture?
- ) Outer capsule- Smooth muscle/ elastic fibers ( thickest in horse and cow. thinnest in carnivores)
- ) White pulp- Periarterial lymphatic sheaths (PALS ) Dense accumulations of T lymphocytes around central arteries. Also contains lymphatic nodules ( B lymphocytes)
- ) Red Pulp: (splenic cords/ blood vessels)
- ) Marginal zone (area between red and white pulp.
What is the direction of blood flow through the spleen?
Splenic artery enters hilus —> trabecular arteries —–> central arteries
when surrounded by white pulp —-> pulp arteries —-> arterioles —-> capillaries
What are some species differences of the spleen?
Canine: Red pulp contains venous/ vascular sinuses.
Feline/ equine/ porcine/ ruminants: poorly developed to no sinuses
Feline/ ruminants: Few PALs in white pulp
Porcine and Ruminants: smooth muscle within red pulp
What are tonsils? What are the main components from most superficial to deepest?
Collections of lymphatic nodules and diffuse lymphatic tissue along the
tongue, pharynx, and larynx
Main components (superficial to deep):
• 1) Epithelial lining - usually stratified squamous
• 2) +/- crypts (deep invaginations of surface epithelium)
• 3) Lymphatic tissue
• 4) Capsule of dense connective tissue
• 5) Glands
What are examples of tonsils with crypts and the species you can find them in?
Lingual tonsil – horse, pig, cow
Tubal tonsil – pig
Paraepiglottic tonsil – pig, sheep, goat
Palatine tonsil – horse, pig, ruminan
What are some tonsils without crypts and what species will you see them in?
Tubal tonsil – ruminants
Paraepiglottic tonsil – cat
Palatine tonsil – carnivore
What kind of tonsillar glands are found in carnivores? In other species?
Carnivores: Mixed (mucus and serous glands)
Others: only mucus glands.
What is MALTS?
MUCOSA- ASSOCIATED LYMPHOID TISSUE (MALT)
Diffuse lymphoid tissue and/or lymphatic nodules in subepithelial connective tissue
What are the names and acronyms for the MALTS found in various areas of the body?
BALT = bronchus-associated lymphoid tissue – in the lung
• GALT = gut-associated lymphoid tissue. (Peyer’s patches within the lining of the small intestine, especially the ileum.)
• NALT = nasal-associated lymphoid tissue • Others (urinary tract, reproductive tract)
What is the main function of the respiratory system?
Provide route for airflow from outside to the lungs. Allows for gas exchange between outside and blood.
Air is:
- cleaned (ie dust is phagocytized by macrophages)
- humidified
- warmed
What are the parts of the upper respiratory system? Lower?
Upper: Tongue, Nasal cavity, pharynx, Larynx
Lower: Trachea , Bronchi, Alveoli, Nerve endings
What are the embryonic origins of the respiratory system?
Structures in cranium from ectoderm
- Oronasal + respiratory epithelia (surface ectoderm)
- Cartilage + other connective tissue (neuroectoderm)
Pharynx/ Larynx to alveoli ( endo and mesoderm)
Laryngo tracheal tube: endoderm
Cartilage/ connective tissue: Mesoderm
What is the steps of embryonic development of lungs?
1.) Foregut forms groove (called laryngo- tracheal grooves)
2.) The Laryngo-tracheal grooves deepen and approach
3.) When groove closes, it becomes laryngo-tracheal tube. Tube then extends caudally forming respiratory diverticulum.
4.) Bifurcation occurs of blind end and forms bronchial buds, which will become L and R lungs/ airways
5.) Bronchial buds grow and branch (into principal bronchi which further branch to form Lobar ( secondary bronchi)) ( like tree), simultaneously pleural cavity is formed around bronchi like a balloon.
*6.) Pigs and ruminants get a 3rd bronchus (tracheal bronchus) comes out further up on trachea.
7.) Continues to branch out (smaller and smaller) to tertiary (segmental) bronchi, and eventually become bronchioles (no cartilage) (Bronchi have cartilage)
8.) Terminal bronchiole ( respiratory bronchiole is formed just before alveoli is formed.)
• Close to capillaries
How does the epithelium change from fetal to adult life in regards to the respiratory tract?
- Fetal have simple cuboidal epithelial at this point, suspended in mesenchyme.
- As they get closer to birth, they become more squamous, and at birth they will be type 1 alveolar cells: simple Squameous and type 2 alveolar cells: Thick cuboidal cells
Which bronchus is more prone to aspiration pneumonia? Why?
Right Bronchus. Less length of principle bronchus.
What is a difference between species in the respiratory system?
Ruminants and pigs have 3rd (tracheal) bronchus
TRUE or FALSE : Bronchioles contain cartilage.
FALSE: Bronchioles do not contain cartilage.
What is the function of type 1 pneumocytes and type 2 pneumocytes? How can you tell them apart?
Type 1 pneumocyte: Simple squamous epithelium, and involved in air exchange at blood air barrier.
Type 2 pneumocyte: Simple cuboidal epithelium. Produces surfactant.
What is the job of surfactant?
Breaks surface tension so lungs dont stick together (think of glass slides sticking together)
What are the layers of the upper trachea and bronchi from furthest inside to outside?
- Lumen
- Mucosa (epithelium) (some goblet cells)
- Lamina propria/Submucosa (hard to tell difference) (glands)
- Muscle/ Cartilage/ Bone
- Adventitia ( Connective tissue)
Same in birds and mammals. Different in fish and herpes.
What type of epithelium is present in the mucosa layer of the trachea/ bronchi?
pseudostratified columnar cilliated epithelium.
What kind of cartilage is present in the trachea?
hayline
What are the parts of the Nasal cavity?
- Vestibule (stratified squamous epithelium, in horses outer nasal epithelium includes hairs) (supported by lamina propria and submucosa)
- Inner Nasal Cavity- (respiratory epithelium, pseudostratified cilliated columnar with goblet cells) (supported by Lamina propria and submucosa)
- Olfactory epithelium: (pesudostratified columnar epithelium, supported by lamina propria (bowmans glands, mucoserous glands) and submucosa)
Label parts A-C of this vestibule in the nasal cavity
A.) Elastic Cartilage
B.) Keratin
C.) Area with loss of Keratin
What supports Nasal turbinates?
Thin bone
In this image which arrow is indicating olfactory epithelium, and which is indicating repsiratory epithelium?
A.) Olfactory
B.) Repiratory
What is the subsections of the pharnx and important characterisitcs?
Nasopharynx ( goblet cells, pseudostratified columnar cilliated epithelium.)
Oropharynx: (Stratified squamous epithelium)
Muscularis: skeletal muscle with loose elastic connective tissue (Circular and longitudinal)
Adventitia (Fiberous connective tissue)
In the oropharynx, how do the glands change based on the species?
Carnivores have mixed glands while others just have mucus glands.
What is the name of the flap of tissue that covers the larynx?
epiglottis, it is made up of hayline cartilage and adipose tissue.
What kind of glands are in the trachea?
Mixed glands, open to lumen via ducts lined with cuboidal epithelium. Elastic fibers in lamina propria (some species, ie cat/ horse)
What is the mucociliary apparatus? What is its job?
Clear mucus in caudo- cranial direction
Trapping & clearing foreign particles (e.g. pathogens, dust, etc.
In the Bronchi/ Bronchioles what is a unique characteristic of the adventitia layer?
Adventitia layer merges into pleural connective tissue.
What is a good stain for Bronchi and Bronchioles ?
Trichome stains
Label all the parts of the Bronchus
A.) Bronchioles
B.) Glands
C.) Connective Tissue
D.) Cartilage
What is an indication of bronchioles becoming terminal bronchioli from a histological standpoint?
Pseudostratified turns to short cuboidal.
Main difference ( no cartilage)
Glands are absent in both of these areas ( accept in cats)
What kind of stain can be used when looking at bronchioles, and what is it staining?
Orecin stain. This highlights the elastic fibers (they will be black)
What are clara cells?
- Protective function (enzymatic degradation of injurious substances, immune response regulation, ect)
- Cuboidal, non cilliated.
- Apical cytoplasm is full of secretory granuales
Label the arrows in this picture of lung tissue
A.) Type 1 pneumocyte ( Thin and flat)
B.) Macrophages
C.) Type 2 pneumocyte (more plump)
What are the three components of the Blood air barrier?
Alveolar cell (type 1 pneumocyte)
BM (Basement membrane) (shared by both cells)
Capillary cell ( endothelial cell)
What covers the pleura? What is unique about domestic mammals? Who does it exclude?
- Mesothelial cells.
- Thick in domestic mammals. Excludes carnivores.
Where is the syrinx in birds?
end of trachea
What is the choana in birds?
Connection between oral and nasal cavity.
What is the difference between tracheal rings in mammals and birds?
mammals: incomplete
birds: complete
What are air sacs for in birds?
Make birds lighter for flight.
Do birds have a diaphragm?
No diaphragm
What are the parts of the Avian nasal cavity?
Vestibule: modified stratified squamous epithelium- keratinized.
Inner nasal cavity: Respiratory epithelium
(Lamina propria, including alveolar mucus glands)
Olfactory epithelium: Pseudostratified columnar epithelium with receptor cells.
What makes the vestibule tissue in avian species different?
The epithelium is stacked (pyramidal)
What is the difference between pharynx, Larynx and trachea in avian species?
No muscularis mucosa
What is the syrinx used for?
Singing
Where is the pessulus located and what is it for?
It is located at the bifurcation of the trachea (the bottom) it is a bone wedge, and it provides support but also is involved in singing.
What are parabronchi? What is their purpose?
air capillaries (alveoli) - Birds
- Gas exchanged ( squamous epithelial cell) endothelial cell (shared basement membrane)
What is some characteristics of avian air sacs?
- simple squamous to cuboidal or cilliated columnar epithelium.
- No air exchange
- Poorly vascularized
- May extend into medullary cavity of bones or into subcutis (species dependent)
- Prone to infection (bacterial/ fungal) (air sacculitis: inflammation)
- should always be transparent.
What can lead to airsacculitus and why?
Small puncture wound in abdomen can lead to airsacculitis since skin of airsacs are so thin.
What are some indications of issues within the air sacs?
Growth of green fuzz ( fungul: most likely aspirgilosis)
Cottage cheese caste: Bacterial infection.
What is some differences between mammals and cold blooded vertebrates? Airway
poor at clearing exudate. Thus prone to pneumonia.
- Lungs are saccular with honeycomb walls( trabeculi seperations) ( faveoli instead of alveoli (not always) much less air exchange surface than mammals)
What supplies blood to the liver?
- ) Portal vein (75% of blood supply) from gut spleen and pancreas ( is oxygen poor/ nutrient rich)
- ) Hepatic artery ( 25 % of blood supply) ( oxygen rich), blood leaves liver via hepatic vein and into vena cava.
Because 2 blood supplies resistant to ischemia.
What is the function of the liver?
Metabolism of proteins, carbohydrates, lipids, hemoglobin, drugs, iron, etc.
Storage of lipids, vitamins A, B & D, glycogen.
Synthesis of albumin, hepcidin, fibrinogen, prothrombin and other clotting factors
(endocrine function)
Detoxification
Conversion of ammonia to urea
Hematopoiesis (in embryo and potentially adult)
Breakdown of RBC and bilirubin metabolism ( kupffer cell/ macrophages)
Where is the bilirubin excreted?
portion via urine, mainly bile.
What occurs in intestines with bilirubin?
Bilirubin is deconjugated by bacterial enzymes and metabolized to urobilinogen (reabsorbed), seterocobilin is excreted in feces and urobilinogen (urine)
How high must the Bilirubin be in order to show icterus/ jaundice? What is icterus/ Jaundice?
Yellowing of mucus membranes, hard palate ( first place to see icterus), eyes, skin, gums, ect
Bilirubin will be greater than 2mg/dL
What is the general structure of the liver?
- Multiple lobes ( grossly)
Parenchyma ( hepatocytes arranged in lobules, surrounded by portal triads ( Hepatic artery, portal vein, bile duct)
- Stroma: Liver capsule (glissons capsule) Septa of fibrous connective tissue (contains portal triads)
What can you see in injured liver tissue?
Hepatic lobules
What is a unique characteristic of pig liver structure?
Thick interlobular septa
What is the direction of blood flow within the liver? The direction of bile flow?
Blood flow is from periphery to center.
Each lobule has a single central vein which receives blood from every sinusoid ( central vein —-> hepatic veins —-> vena cava)
Bile flow from center to periphery via bile canaliculi
What are the three structures in the portal triad?
hepatic artery, portal vein, bile duct
What are hepatocytes?
hexagon- shaped lobules whose boundaries in some species is not clear. They preform almost all functions of liver. Rich in organelles (mitochondria). High regeneration capacity, arranged in plates. Surrounded by sinusoids which are lined by endothelial cells. (Needs sinusoids because of size of protiens.
What are sinusoids?
Highly fenestrated (allowing the flow of plasma into space of disse) vascular channels that get blood from hepatic artery and portal vein, at the periphery of lobules and deliver it into central veins. Lined with epithelial cells, and flanked by plates of hepatocytes.
Contains numerous kupffer cells.
What is the space of Disse?
space between sinusoidal epithelium and hepatocytes. Contain stellate cells and reticular fibers.
- Filled with plasma, hepatocytes form microvilli to occupy most of space. Ito cells can also be found.
What is the major function of ito cells?
Histologically: Large lipid vacuoles
Major function: Storage of vitamin A
Other: Activation in damaged liver = secretion collagen leading to fibrosis.
What is a good stain to see reticular fibers in liver tissue?
Reticulin or silver stain. Collegen type III fibers.
What is the bile canaliculi?
Intracellular space between hepatocytes.
Lined by plasma membranes of adjacent hepatocytes.
Delivers bile from central vein to bile duct.
What does bile canaliculi look like histologically?
Only seen if their is accumulation of bile. Cholestasis
What kind of cells line the bile duct?
Simple columnar epithelial cells.
What surrounds the portal triad?
Fiberous connective tissue
What are the 3 zones of the hepatic lobule? What occurs in each?
- ) Zone 1 / periportal : Highly oxygenated hepatocytes ( more susceptible to Blood born pathogens)
- Gluconeogenesis, Oxidation of fatty acids, and cholesterol synthesis - ) Zone 2 / Midzone
- ) Zone 3/ Centrilobular: Poorly oxygenated hepatocytes (sensitive to hypoxia)
- Drug detoxification due to highest concentration of cytochrome P-450
What is the limiting plate?
First layer of hepatocytes surrounding the portal tact.
In inflammatory conditions, injury to this layer indicates hepatitis
What is the gallbladder? What is its function?
Tubular organ ( mucosa of simple columnar epothelium ( mucosal folds) to absorb salts and water, lamina propri (connective tissue and blood vessels), Muscularis layer, and serosa and adventitia ( in gall bladder fossa)
Function: Store bile produced by liver.
What is the pancreas: What is its main function?
Accessory digestive gland - Similar to salivary gland
Exocrine: Production of digestive enzymes that are carried via pancreatic duct to duodenum,.
Endocrine: Production of hormones (insulin, glucagon, and somatostatin) that regulate carbohydrate metabolism/ control glucose levels.
Histologically what does the pancreas look like?
thin connective tissue capsule which extends inward as septa, partitioning gland into lobules.
Exocrine: Tubuloacinar glands. Acini ( lined by acinar cells, basophillic, contain eosinophillic granules) lumen of acinus communicates directly with intralobular ducts.
Endocrine: Islets of langerhans : interdispersed.
What is centroacinar cells?
Epithelial cells of the intralobular ducts
that project “back” into the lumen of the acinus.
Cytoplasm of the centroacinar cells are pale eosinophilic
and have indistinct borders.
What are differences between the ducts in the pancreas?
Ducts: cells lining ducts secrete water and bicarb to neutrolize stomach acid.
Intralobular duct: Simple cuboidal epithelium
Interlobular duct: Surrounded by connective tissue (simple or stratified columnar ep.
Pancreatic duct: anatomy varies among species. Some fuse with common bile duct just before entry into duodenum. some have 2 ducts.
What can you find near the ampulla ( opening to duodenum) but also among pancreatic duct cells?
Goblet Cells
What can peripancreatic fat necrosis cause?
Pancreatitis
What can you find in the islet of langerhans? What do these cells make? and how can you tell the difference?
- Beta cells: Insulin.
- Alpha cells: Glucacon.
- PP cells: Pancreatic polypeptide.
- Delta cells: Somatostatin.
- Epsilon cells: Ghrelin
Must use immunohistochemistry to determine.
Where are the islets of langerhans found?
Are arranged as irregular cords around abundant capillaries, which receive
the secreted hormones for delivery into the systemic circulation.
What is one of the most common tumors in parrots that present with neurologic signs that derrive from pancreas. What is the cause of the neurologic signs?
Insulinoma ( pancreatic tissue , specifically islets of langerhans)
- Neuro signs from hypoglycemia
What cells in the intestines does parvovirus target?
Crypts in the small intestine. Crypts will regenerate microvillli, these are lost / slough off in parvo virus. Parvo is also known as necrotizing enteritis.
What are the structures in the digestive system? What is the function of the digestive system?
1) Oral cavity/tongue 2) Salivary glands 3) Esophagus 4) Stomach 5) Intestines
- Small Intestine, Large intestine 6) Liver 7) Gall Bladder 8) Pancreas
Function: Prehension, Mastication, Digestion, Storage (forestomachs[ruminants] and cecum [horses], Absorption, Expulsion ( a) Unabsorbed food b) Substances added by accessory glands)
What type of glands are the lingual (minor) salivary glands?
1) Serous (secretes water and proteins, such as amylase(breaks down carbs), lysozyme (protects against infectious organisms) and antibodies)
- Cells with granular eosinophilic (red) cytoplas
2) Mucous (lubrication)
- Cells with pale, “frothy” cytoplasm (mucous does not stain with hematoxylin or eosin)
- Stain lighter than serous glands
What are the 5 types of papillae in the tongue? Which have taste buds which do not?
Do not have tastebuds: Conical, Filiform
Have tastebuds: Fungiform, foliate, vallate (circumvallate)
What are papillae in the oral cavity and what are their function?
- projections of tissue from tongue surface/ modifications of mucosa, with or without taste buds.
- Function: Mechanical, assist in prehension, movement, and breakdown of food. Sense of taste.
What is Marginal papillae, and who has it?
- Excess length papillae, and it is used for nursing, it will regress after weaning, can be seen in carnivores and neonatal pigs.
What are salivary glands? What kind of glands are they?
Glands seperated from oral cavity by long ducts. The four glands are parotid, mandibular, sublingual, and zygomatic.
They are merocrine glands because they do not lose cytoplasm during sevretion.
Classified via type of species producing it, varies by species.
Serous (watery, high in protiens), mucus (high in sugar, high viscosity lubrication), mixed glands
What is the structure of salivary glands?
Multilobular: Secretory units are acini( round) or tubules( elongated). secretory units and ducts are surrounded by myoepithelial cells ( for contraction and movement of product)
What are Serous Demilunes? What are their functions?
Mucous cells covered by a cap of serous cells
Fxn: (secrete lysozyme, conferring antimicrobial activity to mucus)
What is the heiarchy of salivary ducts from smallest to largest?
- ) intercalated duct
- ) intralobular duct
- ) Interlobular duct
- ) Lobular duct
- ) main duct
What is the function of salivary glands?
Moisten oral cavity, lubrication of food, initiate digestion of carbs and lipids, antibacterial activity, stimulate wound healing.
What are messiners submucosal plexus, and auerbachs myenteric plexus?
- components of enteric nervous system
Messiner: Secretory fxn, movement of mucosa, control of blood flow
Auerbach: Peristalsis
What is the structure and function of the esophagus?
* Muscular tube
Fxn: Transports food bolus and liquid from oral cavity to stomach ( oposite direction in ruminants)
Structure: Longitudinal folds (rugae) which allows expansion as food bolus passes.
What are the layers of the mucosa layer of the esophagus?
Mucosa
- ) Epithelium: Stratified squamous epithelium, ( non keratinized in carnivores, variable in other species)
- ) Lamina propria ( may contain mucus glands) ocasional lymhoid molecules ( malt)
- ) Muscularis Mucosae ( longitudinally oriented between layers of smooth muscle, seperation between mucosa and submucosa)
What are the layers of the submucosa layer of the esophagus?
- Seromucinous (mixed) glands
- Main components of secretory product:
Pepsinogen (protease) Lysozyme (bactericidal) Mucous (lubricant)
What are the remaining layers of the esophagus?
Muscularis externa
- 2 layers of muscle: inner circular + outer longitudinal
- Variable muscle composition among species
- Auerbach’s myenteric plexus (between inner circular and outer longitudinal layers)
Adventitia: Cervical portion (connective tissue only)
Serosa: Variable present on thoracic & abdominal portions, lined by simple squamous epithelium (mesothelium)
What is the function and species that have a non glandular stomach?
Partial: Horses
Rumen, Reticulum, and omasum of ruminants
Fxn: Storage and digestion, lined by keratinized squamous epithelium.
What are the three divisions of the ruminant non glandular stomach?
Rumen: leaf like papillae ( stratified squamous epithelium) no muscularis mucosae, has lamina submucosa, muscularis externa, and serosa
Retiuclum: (Honey comb) Muscularis mucosae only present in the apex of crests (folds/ cristae)
Omasom: (Folds) Numerous longitudinal laminae (mucosal folds) projected from wall to lumen. complete continuous mscularis mucosa in laminae. muscularis mucosa trilaminar appearence.
Primary laminae —–> Secondary papillae
What is the function of the rumen?
Fermentation vat
- conversion cellulose to volatile fatty acids
- absorption of volatile acids provide 70% daily energy requirement
- absorbs urea, ammonia, minerals, vitamins, and amino acids produced by bacteria.
What is the function of the reticulum?
Mechanical breakdown (grinding) of ingested materials into fine particles.
What is the function of the omasum?
Assist with grinding of food into finer particles and movement from omasum to abomasum
What lines the glandular stomach and what are the three glandular regions associated with the glandular stomach?
Lined by simple columnar epithelium.
- ) cardiac gland region
- ) Fundic gland region
- ) Pyloric gland region
What is the function of the glandular stomach?
- initial storage, digestion (Hcl and enzymes) and release of food into the duodenum.
What are the 4 layers of the glandular stomach?
Mucosa ( epithelium, lamina propria containing alot of glands, muscularis mucosae)
Submucosa
Muscularis externa
Serosa
What are some structures in the glandular stomach? What are their functions?
Gastric Folds: plicae or rugae: Facilitate expansion of stomach as food is ingested.
Gastric pits: depressions into mucosa (with openings of mucosal glands into pits)
Gastric glands: extensions of gastric pit, lined by various epithelial cell types.
What are some of the epithelial cells of the glandular stomach and what are their functions?
surface lining cells: secrete gel like mucus and bicarb
Regenerative cells: stem cells ( regenerate all types) ( not distinguishable via histo)
Mucus neck cells: similar to surface lining but secrete soluble mucus that lubes gastric contents. (histo same to surface)
Parietal Cells: Secrete HCL ( to acidify stomach lumen (have eosinophilic cytoplasm)
Chief cells: majority at base of gland, secrete pepsinogen, gastric lipase, chymosin (basophilic cytoplasm)
Enteroendocrine cells: secrete gastrin
What seperates the glandular and non glandular stomach in equine?
Margo plicatus
What is the segments and functions of the small intestine?
Segments: Duodenum, Jejunum, Ileum
Fxn: Terminal digestion of food materials. Absorption of nutrients and bile salts.
What are distinguishing features of the small intestines?
Villi (to increase surface area) each enterocyte has microvilli (to further
increase surface area; “brush border”)
- Most numerous in duodenum - Lamina propria contains many lymphoid cells, capillaries and a lacteals
(blindly ending lymphatic channel)
• Crypts of Lieberkühn (intestinal mucosal glands, also present in large
intestine): invaginations of epithelium into lamina propria between villi; many stem cells
What are the layers of the small intestinal wall?
- ) Mucosa (epithelium: simple columnar, lamina propria: CT +lymphoid cells +lacteals + crypts of Lieberkuhn, muscularis mucosae) Muscularis mucosae ( inner circular/ outer longitudinal layers contract rhythmically to shorten villi several times per minute.)
- ) Submucosa: Submucosal glands (brunners glands in duodenum (secrete mucus to help protect from stomach acid), messiners plexus.
- ) Muscularis externa (inner circular, auerbachs plexus, outer longitudinal) for peristalisis.
- ) Serosa
What are the epithelial cells of the small intestine?
surface absorptive cells: most numerous, line surface and crypts of small intestine. For terminal digestion and absorption, manymicrovilli with glycocalyx
Goblet cells: unicellular mucus glands; merocrine secretion, increasing numbers from duodenum to ileum
Enteroendocrine cells: secrete hormone like molecules into lamina propria; long projections may reach lumen.
Regenerative cells: stem cells that produce all epithelial cells of small intestine
Paneth cells: at bottom of crypts; eosinophillic apical secretory granules; make lysozyme, defensins, TNF a (in horses/ cows)
M cells: squamous like cells adjacent to peyers patches. Microvilli replaced by microfolds. Process and transfer antigen to APCs; important for mucosal immunity.
How do you distinguish segments of the small intestines?
Ileum- peyers patches
Duodenum: Brunners glands
What are the segments of the large intestines? What is the function ?
Segments: Cecum, Colon, Rectum, Anal Canal.
Function: Absorption of water/ electrolytes. Production of mucus/ bicarb
* LOTS OF GOBLET CELLS*
What are the epithelial cells of the large intestines?
absorptive: water/ nutrient absorption
Goblet: mucus glands
Regenerative: Stem cells.
Enteroendocrine cells: Secrete hormone like molecules basally into lamina propria ( few in number)
M cells: Squamous like cells adjacent to lymphoid nodules. Transfer antigen to APCs
What is characteristics of the mucosa layer of large intestine?
- Simple columnar epithelium (absorptive and goblet cells)
- Lamina propria (containing crypts of Lieberkühn)
- Muscularis mucosae - Microvilli (brush border) on apex of absorptive cells (enterocytes) -
Large numbers of Goblet cells - NO VILLI IN LARGE INTESTINE
What are special stains that can highlight mucin?
PAS stain (periodic acid schiff) - highlights sugars
Or
Alcian Blue
What are the layers of the large intestine?
Mucosa (epithelium, lamina propria, muscularis mucosae)
submucosa ( individual lymph nodules)
Muscularis externa
What is an identifying characteristic of the rectum histologically?
Histologically similar to colon and cecum, but with fewer crypts
What is the mucosal epithelium of the anus?
stratified squamous epithelium.
What stuctures are identifiable within the anus?
- Anal sac : lies beneath anal sphincter and is lined by stratified squamous epithelium. Secretion is for territory marking.
Perisaccular glands: apocrine glands, malodorus secretion into anal glands. These glands surround anal sac
- Circumanal (perianal/ hepatoid glands)- modified sebaceous glands, junction of anus and haired skin, cells resemble hepatocytes, common site of cancer.
What are two tumors / cancers associated with the anus?
Apocrine Gland Anal Sac Adenocarcinoma (AGASACA) - High metastisis to lungs.
Circumanal (perianal/ hepatoid glands)- Cancer can occur, tumor responds to testosterone, neuter will help prevent reoccurance
What is the differences between the small and large intestines?
Small intestine: Villi, less goblet cells.
Large intestine: No villi, alot of goblet cells.
