LATG C hapters 16-18

1. LATG Chapters 16-18 Unique Anatomy of Lab Animal Species Gnotobiology Statistics

2. Mus musculus • Rapid heart rate (300+/min) and respiration rate (100+/min) • Calcification of the costochondral cartilage • Functional marrow in long bones for life • Extensive mammary tissue going over back and shoulders • Esophagus lacks glands, has stratified squamous epithelium and enters stomach in the middle

3. Mus musculus • The pancreas is diffusely spread through the mesentery ( the same is true for rats and hamsters) • The spleen of males is 50% larger than that of females • The thymus is thinner than that of other species • There is a Harderian gland and two accessory lacrimal glands • Brown fat can be found on the back, neck, and by the kidneys and thymus

4. Rattus norvegicus • Rat skeletons continue to grow throughout their life • Like mice and hamsters, rats have a diffuse pancreas • The liver has no gall bladder to store bile • Accessory sex glands include 2 pairs of prostates, paired seminal vesicles, coagulating glands, ampullary glands, and bulbourethral glands

5. Rattus norvegicus • Rats have an os penis and open inguinal canals • Like the mouse, the rat uterus has 2 horns and 2 cervices • Mature males have larger pituitary and adrenal glands than females • Like the mouse and hamster, the rat has Harderian glands that can cause chromodachyrrhea

6. Mesocricetus auratus • Hamsters have large cheek pouches that are immunologically tolerant sites • They have sebaceous glands on each flank, behind the rib cage - these are more prominent in males • Hamsters have a pre-gastric pouch or diverticulum • The adrenal glands of the male are larger than the female, and the male’s spleen is smaller

7. Mesocricetus auratus • Male accessory sex glands similar to mice and rats • Males have open inguinal canals like mice and rats • Females have duplex uterine horns with 2 cervices like mice and rats • Harderian gland present like mice and rats • Some hamster lines have V-shaped tracheal rings

8. Cavia porcellus • Young are precocious with eyes open, teeth erupted, fully furred, able to walk and eat solid food • All teeth are open rooted and grow continuously • Very large cecum compared to other rodents, ends in cecal appendix • Left adrenal long and thin, right one shorter and flat • Male penis has papillae and two erectile spines • Sex glands, inguinal canal, uterus similar to other rodents • Females have ligament allowing separation of pubic syphysis • Presence of Kurlhoff bodies in some lymphocytes, and heterophils instead of the normal neutrophils

9. Guinea pig • Palatial ostium covers posterior pharynx • Intact vaginal closure membrane • Pubic symphsis under control of relaxin • Sow must be bred before 8-9 months of age

10. Oryctolagus cuniculus • Two “peg teeth” behind primary incisors • Very light weight skeleton (8% BW) • Open rooted teeth like guinea pig • Cleft lip, papillae on tongue • GI tract unique • Peyer’s patches • Sacculus rotundus • cecum ends in vermiform process • colon has haustra and taenia coli • colon has fusus coli for production of night feces = cecotrophs

11. Oryctolagus cuniculus • Highly vascularized ears - used for thermoregulation and access for bleeding/injection • Right and left AV valves bicuspid • Heterophils present as in the guinea pig • Male accessory glands include prostate, seminal vesicles, bulbourethral, and ampullary. No coagulating gland, no os penis. Testes in inguinal pouch not in scrotal sac. • Each uterine horn has its own cervix, like rodents • Rabbits, rats and horses can’t vomit

12. Rabbit • Lagomorphs have two peg teeth • Rabbit skeleton is 8% body weight • sacculus rotundus located at juncture of cecum and ileum • Cecal appendix = vermiform appendix • Neutrophils= heterophils

13. Felis catus • Cats have 2 additional salivary glands - molar and infraorbital • No appendix • Anal glands present, as in dogs • Kidneys have high fat content making them yellowish in appearance • Closed inguinal rings, papillae on penis, only prostate and bulbouretheral glands present in males • Single cervix in females

14. Canis familiaris • Cartilaginous clavicles like cats • Esophagus has numerous mucus glands • Anal glands • Closed inguinal ring, prostate and ampullary gland • Small ovaries

15. Nonhuman Primates • Prosimians and simians • Prosimians include tree shrews, bush babies, lemurs, lorises, and tarsiers • Both groups have articulating clavicles, deciduous and permanent teeth, bony eye sockets, a pendulous penis, scrotal testicles, and an opposable thumb

16. Catarrhinni 32 permanent teeth flat skulls, brow ridges, narrow nasal septum, long nostrils cheek pouches ischial callosities non-prehensile tails better developed opposable thumbs need Vit C but not D3 Platyrrhini 36 permanent teeth rounded skulls, no brow ridges, wide nasal septum, oval nostrils no cheek pouches no ischial callosities prehensile tails less developed opposable thumbs need Vit C and Vit D3 Nonhuman Primates

17. GnotobiologyIntroduction/History • Gnotobiotics= “known life” • Science of keeping animals in a controlled environment; organisms that inhabit body are known • Pasteur experiments over 90 years ago (guinea pigs) • 1946- first germ-free rat colony • 1957-Trexler isolator created

18. Use in Research • Source of foundation stock to be used in the production of barrier- bred animals ie. SPF, GF, DF • Carcinogenesis/mutagenesis • Infections/Immunity • Nutrition • Toxicology, Pharmacology, and Physiology

19. Terminology • Defined Flora (DF): microflora is totally known • Axenic=Germ-free (GF): free of all known organisms; except for its’ own living cells • Specific Pathogen Free (SPF): animals free from specified organisms considered pathogenic • Conventional: Harboring undefined microfauna

20. The Isolator • Components: body, air handling system, entry/exit, operator access • Types: Rigid and flexible • Must provide - temperature control - # of hours of light/darkness - source of sterile air - means of air exhaust

21. Laminar Flow Cabinet • Provide slow-moving, linear-flowing, filtered, sterile air • Use: Removes airborne microbes, prevents contamination • HEPA filtered

22. Sterilization Techniques • Steam autoclaving • Dry heat • Ethylene oxide • Gamma irradiation • Membrane filtration

23. Gnotobiotic Physiologic and Anatomic Characteristics • Intestinal walls are thin • poor muscle development • enlarged cecum • longer lifespan • higher nutritional requirement • higher blood cholesterol • generally smaller internal organs

24. Caesarian Derivation or Embryo Transfer • Entry of disease free breeders into barrier facility • Surgical removal of uterus from time-mated donor animal • Uterus passed through dip tank containing germicide into isolator • Fetuses removed from uterus • Adopted onto donor female-axenic foster mother • Microbiologic monitoring of fostered offspring • Adm. of normal non-pathogenic intestinal flora- ” Schaedler’s cocktail”

25. Why the Need for Statistics/Statistical Calculations? • To draw valid conclusions from data • To distinguish differences from random variability • To make the strongest possible conclusion from the least amount of data • Limitations: No statistical extrapolation

26. Key Words • Hypothesis: assumption of truth • Variables (experimental) - dependent: weight, sex , age - independent • Randomization • Mean- average number

27. Distribution • Distribution= “normal variation” • Bell shaped Curve or Gaussian curve • Most of the examples in a set of data are close to average, while few examples are extreme

28. Statistical Significance • Populations are the same or different • Accepted margin of error: Results occur less than 5% of time if the populations were really identical. • Researcher is 95% sure that results are due to measured data and not normal variation ( 95% confidence level) • Minimum number of animals should be used • (SS ) does not = biological or clinical significance

29. Standard Deviation • How close the various examples are to the mean in a set of data. • Expressed as plus or minus • Steep bell shaped curve= small S.D. • Wide bell shaped curve= large S.D.