Biology

Question 1

Describe the appearance of the Black and Norway rat.

Answer 1

Black: Smaller, thick ears, tail 85% length of body.
Norway: Larger ears, tail longer than body.

Question 2

Name the two hair classes and describe hair growth.

Answer 2

Long (sparse) and short hairs. Hair growth in the young is cyclic with resting and growing periods of 7 days

Question 3

How many teats and where are they located.

Answer 3

6 pairs, three pectoral, three abdominal

Question 4

Rank the size of SD, Wistar, and F-344

Answer 4

SD > Wistar > F-344

Question 5

Rats have what type of eyes? How are they moistened? What is a special characteristic of this secretion?

Answer 5

Exophthalmic eyes. Moistened by secretions from lacrimal gland and medially located Harderian gland. Porphyrins fluoresce

Question 6

What venous structure is present adjacent to the rat eye? How does this differ from the mouse?

Answer 6

Rat: Orbital venous plexus
Mouse: Orbital venous sinus

Question 7

Describe vision in the rat. Number of colors, what spectrum they can see, and what spectrum they are insensitive to.

Answer 7

Dichromatic with 2 cones, 1 of which sees in UV. Insensitive to long wavelengths, i.e. dim red light at 625 nm, although it can affect photoperiod.

Question 8

What is the hearing range of a rat? Where are they most sensitive? What is the ultrasonic range?

Answer 8

250Hz - 80 kHz.
Most sensitive at 8-32 kHz
Ultrasonic = 22 - 80kHz

Question 9

Vertebrae formula

Answer 9

C7, T13, L6, S4, Caud 27-30

Question 10

Costal cartilage?

Answer 10

No true costal cartilage

Question 11

Tibia and fibula structure

Answer 11

Separate proximally, fused distally

Question 12

Dental formula

Answer 12

2(I 1/1, M 3/3)

Question 13

Name the three salivary glands, their products, and how one differs from the mouse.

Answer 13

Parotid: Serous
Submandibular: Mixed (seromuscular in mouse)
Sublingual: Mucous

Question 14

Where is brown fat/multilocular adipose tissue found?

Answer 14

Ventral and lateral portions of the neck

Question 15

What structures are present on each aspect of the colon?

Answer 15

Ascending colon = Oblique mucosal ridges
Transverse and descending = Longitudinal mucosa folds

Question 16

What are the four liver lobes? Where are each visible on necropsy?

Answer 16

Right lateral, left (visible beneath median), median (visible on ‘top’), caudate (around esophagus)

Question 17

Describe passage of bile and pancreatic products.

Answer 17

No gallbladder. Bile from each lobe forms a common bile duct. Pancreatic ducts empty into common bile duct.

Question 18

Where is Steno’s gland located? What does it produce?

Answer 18

Maxillary recess/sinus between maxillary bone and lateral laminae of ethmoid bone contains lateral nasal gland (Steno’s). Similar to salivary gland, produces watery product discharged at rostral end of nasal turbinates to regulate viscosity of mucus layer overlying nasal epithelium.

Question 19

Describe lung structure.

Answer 19

Single left lobe, four right lobes (cranial, middle, accessory, caudal)

Question 20

Describe two unique features of the respiratory system.

Answer 20

Pulmonary vein contains cardiac muscle continuous with heart. No adrenergic supply to bronchial muscles - bronchoconstriction controlled by vagal tone.

Question 21

Describe the male accessory sex glands.

Answer 21

Vesicular glands = seminal vesicles. Prostate = dorsocranial (coagulating), dorsolateral, and ventral.
Bulbourethral = Cowper’s. At base of penis

Question 22

Describe uterus

Answer 22

Bicornuate, two horns and cervices

Question 23

Describe kidney structure. What unique structure predisposes to what research use?

Answer 23

Unipapillate. Superficial nephrons in the renal cortex make rat kidney a model for investigating nephron transport in an in vivo micropuncture system.

Question 24

Name four unique characteristics of the brain.

Answer 24

Lissencephalic
Large olfactory bulbs
Paraflocular lobes of cerebellum in deep sockets of the periotic capsule of skull
Ventricular system lacks foramen of Magendie

Question 25

Where does the spinal cord end?

Answer 25

4th lumbar vertebrae. Filum terminale at the tail, 3rd caudal nerves

Question 26

What provides blood supply to the atria?

Answer 26

Extracoronary from branches of internal mammary and subclavian

Question 27

What does a natural ingredient diet contain? What are two classes? What is a con of this diet type?

Answer 27

Contains agricultural products and by-products. Can be open (formula known) or closed (formula secret). Nutrient composition varies batch to batch. Most common for research

Question 28

What is a certified diet? What type of studies are these diets used on?

Answer 28

Each lot assayed and certified to not exceed maximum concentrations of a set list of contaminants. Tox and GLP studies.

Question 29

What is a purified diet? What is an advantage and two disadvantages? Name one example.

Answer 29

Defined ingredients (casein, sugar, starch, etc.), each composed of a single nutrient or nutrient class. Less variety in nutrient concentration, more expensive and less palatable. AIN-76

Question 30

What is a chemically defined diet? List two cons.

Answer 30

Very basically defined ingredients (amino acids, triglycerides, fatty acids). Cost, lack of palatability.

Question 30

What dietary factor/contaminant needs to be considered?

Answer 30

Phytoestrogens

Question 31

What are two disadvantages of ad libitum feeding? As opposed to what percent feed?

Answer 31

Decreased longevity
Increased cancer risk
70-80% full feed