Seminar - Anatomy and Physiology Flashcards
What is the vertebral formula of mice and rats?
C7, T13, L6, S4, Cocc. 28 (mice) 27-31 (rats)
How many ribs? How many sternal, asternal, and floating?
7 sternal, 6 asternal, 3 floating.
Why is the rat commonly used to model rotator cuff tears?
Well-formed clavicular brace with shoulder anatomy similar to humans.
Describe bone maturation and growth plate fusion in rats. In mice.
Rat bone maturation rate slower than most mammals, ossification not complete until >1 year of age. Growth plates do not fuse in rats. Fusion is variable and incomplete in mice, depending on strain and genotype
Which animals lack haversian systems? (3)
Mice, rats, and hamsters
Dental formula of mice and rats
2 (I 1/1, M 3/3) = 16 teeth total
Describe teeth in rodents.
No deciduous teeth. Incisors are open rooted. Enamel layer on rostral surface of incisors, gives teeth pigment.
Where is the incisive foramina?
Communicates between mouth and nose.
Do rodents have tonsils?
No, have nasal-associated lymphoid tissue.
Name the three salivary glands, their products, and where they open. Why is this important to disease?
Parotid - Serous, diffuse, drains opposite lower molars.
Submaxillary - Mixed, drains posterior lower incisors.
Sublingual - Mucous, drains near submaxillary.
Sendai only infects serous glands.
Describe the sexual dimorphism of the salivary glands.
Male submaxillary gland has more prominent secretory granules. Female has fewer secretory granules in ductal epithelial cells. Submandibular and parotid salivary glands are larger in males as well.
Describe the structure of the esophagus
Entire esophagus composed of striated muscles with keratinized/cornified surface
Describe gastric juice secretion
Continuous, not dependent on food intake. Rate is slower in mice than rats, takes longer to induce gastric ulcers in mice than rats.
What are Paneth cells? What are Brunner’s glands? Which one differs between mice and rats?
Paneth cells produce lysozyme, which may regulate flora. Brunner’s glands produce mucin and bicarbonate to protect the mucosa. Paneth cell granules in SI crypts are large in mice and humans but small in rats.
Describe the cecum in rats.
Rats have no internal septae, have inner constriction dividing cecum into apical and basilar sections. Apical portion only contains lymphoid tissue, like vermiform appendix of man.
Why are mice prone to rectal prolpase?
Short rectum
When are thickened bowel walls normal?
Pregnant and lactating females due to physiological mucosal hyperplasia.
Describe lobation of mouse and rat liver.
Mouse: Median, left, right, and caudate lobe. Gallbladder in cleft of median lobe.
Rat: Median, right lateral, left, and caudate lobe. Bile ducts from each lobe come together to form common bile duct, which drains into descending duodenum. Cannot concentrate or store bile.
Describe common findings in mouse livers. How does this differ from the rat liver?
Anisokaryosis, polykarya, and karyomegaly present at all ages, but increase with age and disease. Extra-medullary hematopoiesis commonly seen, especially in younger mice. Fat vacuoles common.
Rat hepatocytes are more uniform.
Describe the pancreas in mice and rats. Where does the pancreatic duct open in mice and rats? How can pancreatic juice be collected in rats?
More diffuse than in most other mammals.
Rats: Pancreatic duct opens into lower part of common bile duct. Collection via ligation of common bile duct near origin with cannulation near orifice.
Mouse: Pancreatic duct drains into duodenum at greater duodenal papilla.
Where are Islets of Langerhans found in the pancreas? When do their numbers increase?
Scattered irregularly throughout pancreas. Increase in number during pregnancy.
What is Steno’s gland, where is it found, what is its function, and hos is it regulated?
Lateral nasal gland, the largest nasal gland in rats. Surrounds maxillary sinuses and extends into the lateral wall. Glands empty into nasal vestibule. Regulates viscosity of mucus and humidifies inspired air. Homologous to salt gland in marine birds. May be regulated by nervous system so that rapid adjustment of secretory activity in response to inspired air is possible.
What are the two divisions of the olfactory system?
Main: Nasal cavity olfactory system
Accessory: Vomeronasal. Receptors for pheromones, prominent in rodents.
Describe lung lobation
Four right lobes, one left lobe.
Where is cartilage present in the airways?
Only in extrapulmonary airways.
What is the pulmonary branching patten in mice and rats?
Monopodial (branch forms one smaller daughter segment at an angle) as opposed to dichotomous in humans (two equal daughter segments)
What is unique about the respiratory epithelium of rats? How does this impact disease presentation?
Rats have serous cells in their respiratory epithelium. Sendai can be found in trachea.
What is unique about the epithelial lining of the bronchioles in the rat?
Epithelial lining in bronchioles remains high cuboidal on side adjacent to arteriole, opposite side progressively decreases in height.
What is unique about submucosal/bronchial glands in the mouse?
They are rare or absent in the mouse. Epithelial surface cell produces a secretion of lower viscosity of than that of the mucus cell.
Describe the lungs of neonates.
Lungs are immature with no alveoli nor alveolar ducts. Restructuring and development occurs post-natally. Gas exchange occurs in smooth-walled channels and alveolar sacs.
What is unique about the pulmonary vein?
Contains cardiac muscle, not to be confused with medial hypertrophy.
What lab species have precapillary anastomoses between bronchial and pulmonary arteries in the hilar region?
Rats, GPs, opposums, man
In what lab species is there no adrenergic supply to the bronchial muscles, meaning bronchoconstriction of bronchioles is controlled by vagal tone?
Rat and rabbit
Where should cardiac puncture be performed? Why?
Ribs 3-5 on left side, due to small size of left lung.
Describe heart valves in the rat and mouse.
Rat: Aortic and pulmonary valves have three leaflets, mitral and tricuspid valves have two major and one minor accessory leaflets.
Mouse: Aortic and pulmonary valves semilunar. Right AV tricuspid, left bicuspid.
How does the vena cava differ in mice and rats?
Two precavae, right and left. Right drains directly into right atrium, left joins azygous before uniting with postcavae to enter right atrium.
Describe the extracoronary myocardial blood supply in the rat.
Atria receives blood from IMA and subclavian, more similar to fish than higher mammals. Right cardiac arteries provides blood to both atria, but the left cardiac arteries supply only a little of what the left atrium needs.
Describe the AV node and Purkinje fibers in Muridae. What other species are similar?
AV node in Muridae (and rabbit and dog) is elongated slender mass separated from annulus fibrosus by several layers of fat. Purkinje fibers in Muridae (and rabbit, GP, and bat) little to no differentiation b/w Purkinje fibers and ventricular musculature.
Describe EKG finding in Muroidea superfamily.
Very short QT segment, with essentially no ST segment. Neonates have long QT, takes adult form by 4 weeks. Strain difference
In what species are Purkinje fibers large and well-differentiated? In what species are P fibers medium to small and resemble myocardial fibers?
Large: Pigs, ungulates, and bird.
Medium to small: Primates, dogs, cats, and squirrels
What species have unipapillate kidneys?
Rodents, lagomorphs, and insectivores
Compare the kidneys of mice and rats.
Mice have twice the kidney mass per gram body weight, higher relative kidney mass than any other animal. Mouse glomeruli half the size of rat, but have 4.8x more than rats, with double the filtering surface.
How does kidney size vary by sex in mice?
Male mice have larger and heavier kidneys.
How does the parietal glomerular lining vary by sex in mice?
Squamous in females, young males, and castrated males.
Cuboidal in adult, intact males.
Describe concentration of rodent urine.
Highly concentrated
What aspect of rat kidneys makes them unique for kidney function research?
Superficial nephrons in cortex allow for research directed at the transport process along the nephron.
What compound do mice excrete in their urine? Which sex?
Protein, not serum protein. Males more than females.
Describe the seminal vesicles.
Large, ducts enter urethra with ampulla. Fluids help form vaginal plug
Describe the coagulating glands.
Attached to concave surface of seminal vesicles. Fluids help form vaginal plug.
Describe the prostate.
Ventral prostate on ventrolateral sides of bladder. Third pair of prostate glands dorsal to urethra.
Describe the ampullary glands.
AKA gland of ductus deferens. Open into vestibule of ampulla.
Describe the bulbourethral glands.
AKA Cowper’s glands. Lateral to membranous urethra. Enters urethra anterior to diverticulum.
Describe the preputial glands.
SQ tissue near end of penis. Ducts open at tip of prepuce. Sebaceous excretion. May be homologous with clitoral glands of female.
What affects copulatory plugs in male mice?
Size of plugs and frequency of expulsion is higher in single sex grouped males.
Are copulatory plugs always pathologic?
No, can cause obstruction, but can also occur agonally.
When does mean oocyte count in rats start to decrease? What factors are attributed to this decrease?
Peri-natal, with drop by day 11. Atresia and transformation to follicle cells.
Describe the mouse and rat vagina/cervix.
Mouse: Two horns fuse to form a uterine body with single cervix.
Rat: Uterus bicornuate and duplex, with paired cervices.
Where does the urethra exit? How does this differ from domestic animals?
Urethra opens to exterior at urethral orifice. Does not enter vagina as in other domestic mammals.
What is unique about the vagina at birth? When does this change?
Sealed caudally at birth by transverse epithelial septum. Degeneration occurs at 20-35 days, continuous by 40-80 days.
Describe the clitorus.
Modified sebaceous gland, homologous to male penis.
Describe the clitoral glands.
AKA bulbi vestibuli. Modified sebaceous, homologous to preputial.
Describe the tubuloalveolar glands.
Located in cranial part of urethral wall. Homologous to male prostate. Best developed at 30 days of age, then undergo degeneration to resemble prostate of castrated male.
Describe mammae in mice and rats.
Mice: 5 pairs (3 thoracic, 2 inguinal)
Rats: 6 pairs (3 thoracic, 1 abdominal, 2 inguinal)
When is onset of puberty in mouse and rat? Cycle length? Ovulation?
Mouse: Onset 28 days, 4-5 day cycle, ovulate 2-3 hour after estrus onset
Rat: Onset 50-72 days, 4-5 day cycle, ovulate 8-11 hours after estrus onset
Describe vaginal cytology at each stage of estrous.
Proestrus: Small, nucleated epithelial cells, leukocytes, occasional cornified cells
Estrus: 75% nucleated cells, 25% cornified cells. Cornified cells increase in number as estrus progresses
Metestrus: Large number of leukocytes and cornified cells, cellular debris, and large, flat nucleated (pavement) cells
Diestrus: Primarily leukocytes and small number of epithelial cells
How do rodents adapt to heat? To cold?
Heat: No sweat glands and cannot pant. Lose some heat by salivary secretion, primarily respond by burrowing. Chronically adapted mice have vascularized ears and long tails.
Cold: Chronic exposure replaces shivering thermogenesis with non-shivering thermogenesis. Brown fat controlled by thyroid hormones and catecholamines. Total heat can almost triple BMR.
Where can white fat develop? Where is it consistently located?
Can develop anywhere in body. Consistently found along mesenteric vessels, kidneys, attached to gonads and ducts, and in SC axillary and inguinal regions.
Where can brown fat develop? Where is it consistently found?
No new areas are developed postnatally. Used in non-shivering thermogenesis. Constantly found between scapulae, axillary region, cervical region, adjacent to thymus, along thoracic aorta, kidney hilus, and urethra.
Describe the harderian gland, including location of duct opening and function.
Located behind eye, single duct opens at base of nictitating membrane. Lubricates edges of eyelids with porphyrin.
How many lacrimal glands are there? What is a unique feature of one?
Two, extraorbital and infraorbital. Extraorbital in rats has striking epithelial megalokarya, not to be confused with disease state.
Where is Zymbal’s gland located. Which disease condition is common?
Base of ear, neoplasia
Which gender has more peripheral blood granulocytes?
Males
The splenic red pulp is an active hematopoietic site when?
Throughout life
What pigment accumulates in the red pulp as mice age? Especially in what group?
Iron (hemosiderin). Multiparous females
Where is melanosis appreciated?
Olfactory bulbs, optic nerves, heart valves, spleen and splenic capsule
Are accessory adrenals common in mice or rats?
Mice
Which zones are not distinguishable in the mouse adrenal?
Zona reticularis and fasciculata
What is a unique feature of the mouse adrenal? What is it composed of?
The X zone of the cortex, which surrounds medulla. X zone is composed on basophilic cells and appears in mice around 10 days of age.
When does the X zone disappear? What sex difference occurs?
Disappears when males reach sexual maturity and females undergo first pregnancy. Disappears gradually in virgin females. During involution, undergoes marked vacuolation in females but not males.
How do the adrenals of wild and lab rats compare?
Adrenals of domestic rats are smaller.
How does adrenal size differ in female and male rats and mice?
Adrenals larger in females.
