Histology Flashcards
What are the 3 parts of the basic structure of blood vessels?
- Tunica intima
- Tunica media
- Tunica adventitia
What is tunica intima made of?
endothelium supported by basement membrane and CT
What is tunica media made of?
smooth muscle tissue, thick in arteries and thin in veins
What is tunica adventitia made of?
Connective tissue, thin in the arteries and thick in the veins
What is the structure of collagen?
It’s a tropocollagen monomer
Where can type 1 collagen be found?
Fibrous supporting tissue skin, tendons, ligaments and bone
Where is type 2 collagen found?
In hyaline cartilage, in the ground substance
What is type 3 collagen? What does it have an affinity to?
Reticulin fibres, with an affinity to silver salts
Where can type 3 collagen be found?
In highly cellular tissues such as the liver, bone marrow and lymphoid organs
Where can type 4 collagen be found?
In the basement membrane
Where can type 5 collagen be found?
In the embryo and placenta
What does type 7 collagen do?
Forms special anchoring fibrils that links ECF to basement membranes
What are the cells of the central glia?
- Macroglia : astrocytes, oligodendrocytes, ependymal cells
- Microglia
What are the peripheral glial cells?
Schwann cells, satellite glial cells
What are chondrons made of? (3)
Chondrocyte cluster + basophilic capsule + territorial matrix
What does the perichondrion cover?
Elastic and hyaline cartilage
What does perichondrion NOT cover?
Fibrocartilage
What are the central (primary) lymphoid organs?
Bone marrow and thymus
What is the role of the central lymphoid organs?
Production and early selectin of lymphocytes
What are the peripheral (secondary) lymphoid organs?
Lymph node, spleen, tonsils, MALT
What is the role of the peripheral lymphoid organs?
Maintain mature lymphocytes and initiate adaptive immune response, site of lymphocyte activation
Which layers is the gallbladder missing?
- muscularis mucosae
- tela submucosa
What is the order of tunica muscularis in the gallbladder?
Circular, longitudinal, oblique
Which follicles have a germinal center?
secondary lymph follicles
What is the role of the dendritic cells in the paracortex of lymph node?
Present antigen to the T cells
What is the role of the mast cells, what do they contain?
produce Ab for inflammation, contain heparine and histamine granules
How are plasma cells recognizable? (2)
Eccentric nuclei and cartwheel arrangement of heterochromatin
What is present in the mitochondria of brown adipocytes?
Cytochrome oxidase
What is heat control by brown adipocytes under the control of?
Of the sympathetic nervous system
How are the muscle layers in the tunica muscularis of the trachea
transverse and longitudinal
What are 2 things that tunica mucosa of the urothelium doesn’t have?
- CT papillae
- Lamina muscularis mucosae
Where is the tela submucosa absent in the urothelium?
In the trigone of the bladder
What are the muscle layers of detrusor muscle (tunica muscularis)
Inner longitudinal
Middle circular
Outer longitudinal
What are the 3 layers in SSNK?
- Stratum basale
- Stratum spinosum
- Stratum planocellulare
Muscles of the 3 parts of oesophagus
Upper 1/3 : inner circular and outer longitudinal = skeletal muscle
Middle 1/3 : inner circular = skeletal, outer longitudinal = smooth
Inferior 1/3 : inner circular + outer longitudinal = smooth muscle
What type of glands are found in the lamina propria mucosae of oesophagus?
Schaffer’s glands, simple or branched tubular mucous glands
What is lamina muscularis mucosa?
A longitudinal smooth muscle layer characteristic of digestive viscera
What are the 5 layers of SSK?
- stratum basale /germinativum
- stratum spinosum / polygonale
- stratum granulosum
- stratum lucidum
- stratum corneum
Which granules in cytoplasm of stratum granulosum of SSK
Dense basophilic granules : keratohyalin
What is the tunica media of the small arteries?
5-10 layers of SMC
What do small arteries have, and what do they miss?
They have the internal elastic lamina and no external elastic lamina
What is the tunica media of arterioles?
1-4 layers of SMC
What does Verhoeff’s elastic stain do?
Elastic fibres black, collagen fibres red
What are the 4 layers of the penis?
- Skin
- Dartos fascia
- Buck’s fascia
- Tunica albuginea
What is the order of arteries to the penis for erection etc?
- Internal iliac
- Internal pudendal
- Deep artery of the penis
- Helicine artery
In which structure do we find Peyer’s patches?
In the ileum
What do duodenum, jejunum and ileum have in common?
Tunica mucosa is simple columnar epithelium, and has plcae circularis (aka valves of kerkring)) and intestinal villi
What are goblet cells?
Unicellular glands that release mucoid granules filled with mucin through exocytosis. has Y shaped nucleus. Mucin is not stained in HE
2 main cell types in pineal gland
Pinealocytes and astroglial cells
What do pinealocytes release
calcium, which condenses and forms corpora arenacea = brain sand
What are the 3 layers of the adrenal cortex?
- zona glomerulosa
- zona fasciculata
- zona reticularis
what does zona glomerulosa of adrenal cortex produce?
Mineralocorticoids (aldosterone)
What does zona fasciculata of adrenal cortex produce?
glucocorticoids (cortisol)
What are the 4 main characteristics of the zona reticularis of adrenal cortex?
- eosinophilic bc less lipid granules
- brown lipofuschin granules in cytoplasm
- pycnotic nuclei
- produce androgens
Which cells make up the adrenal medulla and why are they called like this?
Chromaffin cells due to affinity to chrome salts
What is the role of the chromaffin cells?
Convert NE to E which will the be sent to the vessel
What are the 2 main types of cells in the parathyroid gland?
- Chief (principal) cells
- Oxyphil cells
What do chief cells of the parathyroid gland secrete?
PTH
What do oxyphil cells of the parathyroid gland secrete?
They secrete parathyroid hormone related protein, and calcitriol
What is calcitriol?
An analog of vitamin D
Where does the parathyroid gland come from embryologically?
- Inferior parathyroid gland = 3rd pharyngeal pouch
- Superior parathyroid gland = 4th pharyngeal pouch
What does the calcitonin immunostaining and hematoxylin staining do?
It colours the C cells brown
What lines the follicles in the thyroid gland?
Squamous, cuboidal or low columnar secretory epithelium
What do the secretory cells of the follicles in the thyroid gland produce?
T3 and T4 hormones
What fills the follicular lumen in the thyroid gland?
Colloid material (glycoprotein complex thyroglobulin) which stores the thyroid hormones
What can we find in the interfollicular space (parafollicular space) of the thyroid gland?
- Mixed follicles
- Solid nest cells
What is the embryonic origin of solid nest cells? (thyroid gland)
endodermal origin
What are the 2 types of solid nest cells? (thyroid gland)
Main cells and C cells
What are properties of the Main cells of the thyroid gland? (4)
- Polygonal, elongated or spindle shaped
- Strongly eosinophilic cytoplasm
- Stem cell nature
- Impossible to identify with HE
What are the properties of the C cells of the thyroid gland?
- Pale cytoplasm (paler than other cells in this slide)
- Responsible for secretion of calcitonin
What does Gomori’s chrome hematoxylin-phyloxin do?
Stains Gomori’s substance : the neurophysin dark blue / purple. It is also used to show the different cell types in the adenohypophysis
What is neurophysin?
The transporter molecule for oxytocin and vasopressin in neurosecretory cells
What are the cell types in the adenohypophysis?
Chromophobes (don’t like stain) and chromophils, which are subdivided into acidophils and basophils
What are the types of acidophils in the adenohypophysis and what do they secrete?
alpha 1 (somatotrophs) - GH alpha 2 (lacototrophs) - PRL
What are the types of basophils in the adenohypophysis and what do they secrete?
Beta 1 (corticotrophs) - ACTH Beta 2 (thyrotrophs) - TSH Delta 1 (gonadotrophs) - FSH Delta 2 (gonadotrophs) - LH
What are Herring bodies?
dilated parts of axons from the hypothalamus which have accumulated neurosecretory material. It is stained dark.
What does the neurohypophysis develop from?
From the floor of the diencephalon (ectodermal origin)
What does the adenohypophysis develop from?
From the hypophyseal placode (ectodermal origin)
What are the 2 parts of the neurohypophysis?
Pars nervosa and the infundibular stalk
What are the 3 parts of the adenohypophysis?
- Pars distalis (anterior lobe)
- Pars tuberalis
- Pars intermedia
What is pars intermedia of the adenohypophysis made of? (2)
Basophilic cell cords and follicles lines by chromophobe cells containing colloid material
What is the neurohypophysis made of? (2)
Unmyelinated axon of secretory neurons and pituicytes (type of astrocyte)
What are the 2 types of nuclei in the hypothalamus and what do they produce?
- Paraventricular nucleus - oxytocin and ADH
- Supraoptic nucleus - ADH and oxytocin
How are molecules transported in the hypophysis?
Coupled to neurophysin and through the supraoptico-hyophyseal tract and the paraventriculohypophyseal tract, to the neurohypophysis
Which cells line the third ventricle?
ependymal cells
What is the nucleus basalis of Meynert?
cholinergic neurons that form the sole source of cholinergic innervation of the cortex. Important in Alzeihmer’s.
What type of tissue is the dura matter?
dense, irregular collagen CT covered internally by flat epithelial cells
What type of tissue is the arachnoid?
Fibrocollagenous CT with trabeculae radiating inwards
What type of tissue is the pia matter?
Delicate, loose CT - with collagen fibers under the epithelial cell layer
What does cresyl violet stain?
Basic dye
- Nissl’s substance : deep purple
- Nucleus : purple
- CT fibers : light blue
- RBC : blue
What does luxol fast blue stain?
Myelin staining method
- Binds to lipoproteins of the myelin : blue
- Nucleoproteins : purple / blue
What are the 2 molecules that keep the myelin sheath together?
- MBP : myelin basic protein
- PLP : proteolipid protein (PO in PNS)
Which cells form the myelin sheath in the PNS?
Schwann cells
2 properties of sensory ganglia
- NO synapses
- Pseudounipolar neurons with a central and peripheral process
What is the role of the perineurium?
It maintains the high endoneurial fluid pressure, which is higher than the pressure in the extrafascicular tissue
Diameter of an axon without myelin
1,5 to 2 micrometres
Which protein precipitates in the myelin sheath?
neurokeratin, it stains eosinophilic
What does Bielschowsky’s impregnation do?
It is a type of silver impregnation that stain neurofibrils, reticular fibres, nuclei of glial cells BLACK
What are the characteristics of the autonomic ganglia? (3)
- Multipolar neuron
- CT capsule
- Receives info from preganglionic neuron through synapse
What is the neuropil?
An are in the nervous system composed of mostly unmyelinated axon, dendrites and glial cell processes (so inside ggl)
What is the diameter of multipolar neurons in autonomic ganglions?
20-45 micrometers
What is the parasympathetic pathway to the submandibular ganglion?
Superior salivatory nucleus of pons (CN VII) - Chorda tympani - submandibular ganglion
What is used for cholinesterase enzyme histochemistry?
DAB diaminobenzidien
In which layer are the corpuscule of Meissner found?
In the dermal papillary layer of hairless skin
What is a Meissner corpuscule made of?
Made of flattened Schwann cells that form lamellae parallel to the skin surface.
What connects the Meissner corpuscule to the epidermal basal membrane?
interlamellar collagen fibers and microfilaments, through the upper pole
What happens to nerve cells that enter the Meissner corpuscle?
They lose their myelin sheath and run spirally among the lamellae to the superficial pole
What does the epidermis develop from?
from the surface ectoderm
What does the dermis develop from?
From the mesenchyme
What are the 2 layers of the dermis?
- Papillary layer (loose CT, dermal papillae)
- Reticular layer (dense CT, collagen and elastic fibers)
Which subcutaneous layers NEVER contain fat cells?
eye lids and penis
What is reticular cutis?
Strong CT strands that extend from the fascia to the dermis, tether the skin
What do eccrine glands do?
Produce a clear, odorless sweat consisting mainly of water, through merocrine secretion
What do Pacinian corpuscules detect?
Coarse touch, pressure and vibration
What gland structure do eccrine glands have?
Coiled tubular, helical course in the dermis. Lose their wall in the epidermis
Where can pacinian corpuscles be found?
Deep dermis and hypodermis
What are pacinian corpuscles classified as?
- Encapsulated sensory nerve ending
- A single peripheral neural process encapsulated by 30 layers of flattened Schwann cells and fibroblasts.
- Dense core and lamellar structure
What are the 2 types of fibers in the muscle spindle?
Nuclear chain fiber and nuclear bag fiber
What are the types of nerve endings for muscle spindle?
Annulospiral
Flower spray
Gamma motor fibers
What separates the paired posterior funiculi?
Posterior median septum (composed of neuroglia cells)
Which cells line the central canal of SP?
The ependymal cells (type of CNS glial cell)
Where is the rexed lamina II?
Substantia gelatinosa is in the dorsal horn
What are the 3 layers of the cerebellar cortex?
- Outer molecular layer
- Purkinje layer
- Inner granular layer
Which cells do we find in the outer molecular layer of cerebellar cortex?
Stellate and basket cells
Which cells do we find in the inner granular later of the cerebellar cortex?
Granular cells and golgi cells
What is a glomerular synapse? (glomerulus)
- Axon of Golgi
- Dendrite of granular cell
- Mossy fiber (afferent)
- Glial sheath
Which marker is used for pan filament neuronal neurofilament immunocytochemistry?
SMI311, marks neurons - convenient to trace the dendritic arborization of Purkinje cells
What are lugaro cells?
Bipolar, inhibitory cells that lie in the granular cell later below the purkinje cells