LATG CLATG Chapters 16-18hapters 16-18

Unique Anatomy of Lab Animal SpeciesUnique Anatomy of Lab Animal Species

GnotobiologyGnotobiology

StatisticsStatistics

Mus musculusMus 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

Mus musculusMus 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

Rattus norvegicusRattus 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

Rattus norvegicusRattus 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

Mesocricetus auratusMesocricetus auratusHamsters have large cheek pouches that are Hamsters have large cheek pouches that are immunologically tolerant sitesimmunologically tolerant sites

They have sebaceous glands on each flank, behind the They have sebaceous glands on each flank, behind the rib cage - these are more prominent in malesrib cage - these are more prominent in males

Hamsters have a pre-gastric pouch or diverticulumHamsters have a pre-gastric pouch or diverticulum

The adrenal glands of the male are larger than the The adrenal glands of the male are larger than the female, and the male’s spleen is smallerfemale, and the male’s spleen is smaller

Mesocricetus auratusMesocricetus auratusMale accessory sex glands similar to mice and ratsMale accessory sex glands similar to mice and rats

Males have open inguinal canals like mice and ratsMales have open inguinal canals like mice and rats

Females have duplex uterine horns with 2 cervices like Females have duplex uterine horns with 2 cervices like mice and ratsmice and rats

Harderian gland present like mice and ratsHarderian gland present like mice and rats

Some hamster lines have V-shaped tracheal ringsSome hamster lines have V-shaped tracheal rings

Cavia porcellusCavia porcellus

Young are precocious with eyes open, teeth erupted, Young are precocious with eyes open, teeth erupted, fully furred, able to walk and eat solid foodfully furred, able to walk and eat solid foodAll teeth are open rooted and grow continuouslyAll teeth are open rooted and grow continuouslyVery large cecum compared to other rodents, ends in Very large cecum compared to other rodents, ends in cecal appendixcecal appendixLeft adrenal long and thin, right one shorter and flatLeft adrenal long and thin, right one shorter and flatMale penis has papillae and two erectile spinesMale penis has papillae and two erectile spinesSex glands, inguinal canal, uterus similar to other Sex glands, inguinal canal, uterus similar to other rodentsrodentsFemales have ligament allowing separation of pubic Females have ligament allowing separation of pubic syphysissyphysisPresence of Kurlhoff bodies in some lymphocytes, and Presence of Kurlhoff bodies in some lymphocytes, and heterophils instead of the normal neutrophilsheterophils instead of the normal neutrophils

Guinea pigGuinea pig

Palatial ostiumPalatial ostium covers posterior pharynx covers posterior pharynx

Intact vaginal closure membraneIntact vaginal closure membrane

Pubic symphsisPubic symphsis under control of relaxin under control of relaxin

Sow must be bred before 8-9 months of ageSow must be bred before 8-9 months of age

Oryctolagus cuniculusOryctolagus cuniculusTwo “peg teeth” behind primary incisorsTwo “peg teeth” behind primary incisors

Very light weight skeleton (8% BW)Very light weight skeleton (8% BW)

Open rooted teeth like guinea pigOpen rooted teeth like guinea pig

Cleft lip, papillae on tongueCleft lip, papillae on tongue

GI tract uniqueGI tract unique Peyer’s patchesPeyer’s patches Sacculus rotundusSacculus rotundus cecum ends in vermiform processcecum ends in vermiform process colon has haustra and taenia colicolon has haustra and taenia coli colon has fusus coli for production of night feces = cecotrophscolon has fusus coli for production of night feces = cecotrophs

Oryctolagus cuniculusOryctolagus cuniculusHighly vascularized ears - used for thermoregulation and Highly vascularized ears - used for thermoregulation and access for bleeding/injectionaccess for bleeding/injection

Right and left AV valves bicuspidRight and left AV valves bicuspid

Heterophils present as in the guinea pigHeterophils present as in the guinea pig

Male accessory glands include prostate, seminal Male accessory glands include prostate, seminal vesicles, bulbourethral, and ampullary. No coagulating vesicles, bulbourethral, and ampullary. No coagulating gland, no os penis. Testes in inguinal pouch not in gland, no os penis. Testes in inguinal pouch not in scrotal sac.scrotal sac.

Each uterine horn has its own cervix, like rodentsEach uterine horn has its own cervix, like rodents

Rabbits, rats and horses can’t vomitRabbits, rats and horses can’t vomit

RabbitRabbit

Lagomorphs have two peg teethLagomorphs have two peg teeth

Rabbit skeleton is 8% body weightRabbit skeleton is 8% body weight

sacculus rotundus located at juncture of cecum sacculus rotundus located at juncture of cecum and ileumand ileum

Cecal appendix = vermiform appendixCecal appendix = vermiform appendix

Neutrophils= heterophilsNeutrophils= heterophils

Felis catusFelis catus

Cats have 2 additional salivary glands - molar and Cats have 2 additional salivary glands - molar and infraorbitalinfraorbital

No appendixNo appendix

Anal glands present, as in dogsAnal glands present, as in dogs

Kidneys have high fat content making them yellowish in Kidneys have high fat content making them yellowish in appearanceappearance

Closed inguinal rings, papillae on penis, only prostate Closed inguinal rings, papillae on penis, only prostate and bulbouretheral glands present in malesand bulbouretheral glands present in males

Single cervix in femalesSingle cervix in females

Canis familiarisCanis familiarisCartilaginous clavicles like catsCartilaginous clavicles like cats

Esophagus has numerous mucus glandsEsophagus has numerous mucus glands

Anal glandsAnal glands

Closed inguinal ring, prostate and ampullary glandClosed inguinal ring, prostate and ampullary gland

Small ovariesSmall ovaries

Nonhuman PrimatesNonhuman Primates

Prosimians and simiansProsimians and simians

Prosimians include tree shrews, bush babies, lemurs, Prosimians include tree shrews, bush babies, lemurs, lorises, and tarsierslorises, and tarsiers

Both groups have articulating clavicles, deciduous and Both groups have articulating clavicles, deciduous and permanent teeth, bony eye sockets, a pendulous penis, permanent teeth, bony eye sockets, a pendulous penis, scrotal testicles, and an opposable thumbscrotal testicles, and an opposable thumb

Nonhuman PrimatesNonhuman Primates

CatarrhinniCatarrhinni 32 permanent teeth32 permanent teeth flat skulls, brow ridges, flat skulls, brow ridges,

narrow nasal septum, long narrow nasal septum, long nostrilsnostrils

cheek pouchescheek pouches ischial callositiesischial callosities non-prehensile tailsnon-prehensile tails better developed better developed

opposable thumbsopposable thumbs need Vit C but not Dneed Vit C but not D33

PlatyrrhiniPlatyrrhini 36 permanent teeth36 permanent teeth rounded skulls, no brow rounded skulls, no brow

ridges, wide nasal septum, ridges, wide nasal septum, oval nostrilsoval nostrils

no cheek pouchesno cheek pouches no ischial callositiesno ischial callosities prehensile tailsprehensile tails less developed opposable less developed opposable

thumbsthumbs need Vit C and Vit Dneed Vit C and Vit D33

GnotobiologyGnotobiologyIntroduction/HistoryIntroduction/History

Gnotobiotics= “known life”Gnotobiotics= “known life”

Science of keeping animals in a controlled environment; Science of keeping animals in a controlled environment; organisms that inhabit body are knownorganisms that inhabit body are known

Pasteur experiments over 90 years ago (guinea pigs)Pasteur experiments over 90 years ago (guinea pigs)

1946- first germ-free rat colony1946- first germ-free rat colony

1957-Trexler isolator created1957-Trexler isolator created

Use in ResearchUse in Research

Source of foundation stock to be used in the Source of foundation stock to be used in the production of barrier- bred animals ie. SPF, GF, production of barrier- bred animals ie. SPF, GF, DFDF

Carcinogenesis/mutagenesisCarcinogenesis/mutagenesis

Infections/ImmunityInfections/Immunity

NutritionNutrition

Toxicology, Pharmacology, and PhysiologyToxicology, Pharmacology, and Physiology

TerminologyTerminology

Defined Flora (DF): microflora is totally Defined Flora (DF): microflora is totally knownknownAxenic=Germ-free (GF): free of all known Axenic=Germ-free (GF): free of all known organisms; except for its’ own living cellsorganisms; except for its’ own living cellsSpecific Pathogen Free (SPF): animals Specific Pathogen Free (SPF): animals free from specified organisms considered free from specified organisms considered pathogenicpathogenicConventional: Harboring undefined Conventional: Harboring undefined microfaunamicrofauna

The IsolatorThe Isolator

Components: body, air handling system, entry/exit, Components: body, air handling system, entry/exit, operator accessoperator access

Types: Rigid and flexibleTypes: Rigid and flexible

Must provide Must provide - temperature control - temperature control - # of - # of hours of light/darkness hours of light/darkness - source of sterile air - source of sterile air - means of air exhaust - means of air exhaust

Laminar Flow CabinetLaminar Flow Cabinet

Provide slow-moving, linear-flowing, filtered, sterile airProvide slow-moving, linear-flowing, filtered, sterile air

Use: Removes airborne microbes, prevents Use: Removes airborne microbes, prevents contaminationcontamination

HEPA filteredHEPA filtered

Sterilization TechniquesSterilization Techniques

Steam autoclavingSteam autoclaving

Dry heatDry heat

Ethylene oxideEthylene oxide

Gamma irradiationGamma irradiation

Membrane filtrationMembrane filtration

Gnotobiotic Gnotobiotic Physiologic and Anatomic Characteristics Physiologic and Anatomic Characteristics

Intestinal walls are thinIntestinal walls are thin

poor muscle developmentpoor muscle development

enlarged cecumenlarged cecum

longer lifespanlonger lifespan

higher nutritional requirementhigher nutritional requirement

higher blood cholesterolhigher blood cholesterol

generally smaller internal organsgenerally smaller internal organs

Caesarian Derivation or Embryo TransferCaesarian Derivation or Embryo Transfer

Entry of disease free breeders into barrier facilityEntry of disease free breeders into barrier facilitySurgical removal of uterus from time-mated Surgical removal of uterus from time-mated donor animaldonor animalUterus passed through dip tank containing Uterus passed through dip tank containing germicide into isolatorgermicide into isolatorFetuses removed from uterusFetuses removed from uterusAdopted onto donor female-axenic foster motherAdopted onto donor female-axenic foster motherMicrobiologic monitoring of fostered offspringMicrobiologic monitoring of fostered offspringAdm. of normal non-pathogenic intestinal flora- Adm. of normal non-pathogenic intestinal flora- ” Schaedler’s cocktail” ” Schaedler’s cocktail”

Why the Need for Why the Need for Statistics/Statistical Calculations?Statistics/Statistical Calculations?

To draw valid conclusions from dataTo draw valid conclusions from data

To distinguish differences from random To distinguish differences from random variabilityvariability

To make the strongest possible conclusion from To make the strongest possible conclusion from the least amount of datathe least amount of data

Limitations: No statistical extrapolationLimitations: No statistical extrapolation

Key WordsKey Words

Hypothesis: assumption of truthHypothesis: assumption of truth

Variables (experimental) Variables (experimental) - dependent: weight, sex , age - dependent: weight, sex , age - independent - independent

RandomizationRandomization

Mean- average numberMean- average number

DistributionDistribution

Distribution= “normal variation” Distribution= “normal variation”

Bell shaped Curve or Gaussian curveBell shaped Curve or Gaussian curve

Most of the examples in a set of data are close to Most of the examples in a set of data are close to average, while few examples are extremeaverage, while few examples are extreme

Statistical SignificanceStatistical Significance

Populations are the same or different

Accepted margin of errorAccepted margin of error: Results occur less than 5% of : Results occur less than 5% of time if the populations were really identical.time if the populations were really identical.

Researcher is 95% sure that results are due to Researcher is 95% sure that results are due to measured data and not normal variation ( measured data and not normal variation ( 95% 95% confidence levelconfidence level))

Minimum number of animals should be usedMinimum number of animals should be used

(SS ) does not = biological or clinical significance(SS ) does not = biological or clinical significance

Standard DeviationStandard Deviation

How close the various examples are to the mean How close the various examples are to the mean in a set of data.in a set of data.

Expressed as plus or minus Expressed as plus or minus

Steep bell shaped curve= small S.D.Steep bell shaped curve= small S.D.

Wide bell shaped curve= large S.D.Wide bell shaped curve= large S.D.