HOC 4&5: BIOLOGY, PHYISOLOGY AND ETHOLOGY
MOUSE
Introduction
- Mus musculus
- Most knowledge of all mammals
- Low economics: short life and gestation + large litter/offspring
- Lot of in- and outbred strains (easy genome manipulation)
- Research topics: cancer, endocrine and auto-immune diseases…
Behaviour
- Very social (captivity not good)
- In the wild: social hierarchy ( dominant male, hierarchy of females, subordinate males
and juveniles)
- Crepuscular: most active during twilight
- Activities: breeding, digging, next building…
- Complex communication system: sound + olphactory
o Pheromones + proteins & sex hormones in urine as communication source
- Territorial (fighting wounds visible by subordinates)
Anatomy and physiology
General
- Small, short legs, hairless tail
- Hypodont: teeth keep growing
- Olphactory and hearing: good
- Vision: not good (red light to perform night work during day cuz they can’t see it)
Respiratory system
- 3 sections
Anterior: nostrils, nasal cavities and nasopharynx
Intermediate: larynx, trachea and brochi
Posterior: left lung (1 lobe) and right lung (4 lobes)
- Large body surface to weight ratio
Fast respiratory rate
High RBC concentration and oxygen capacity (right shift in scale)
Great sensitivity to water loss
Small thermoneutral range: 29.6° - 30.5°
Cardiovascular system
- Normal anatomy
- Mean SBP = 84-105mmHg (! doesn’t change when body temp raises!)
Gastro-intestinal system
- Omnivorous
, - Coprophagy: eat feces bcs contains lots of bacteria (optimal nutritional activity)
- Esophagus optimal for gavage
- No appendix
- Rib cage around liver
Urinogenital system
- Mammal: right kidney anterior to left
- Lot of glomeruli: big filtration area
- High concentrated urine: lot of proteins (taurine, creatinine, mups (allergies!))
- Urinating: 1 or 2 drops a time
- Females: 5 mammary glands throughout body, paired ovaries & oviducts, clitoris with
paired clitoral glands
- Males: paired testes, penis with os penis (schaambeen), prostate with glands&ducts
- Sex determination: genital papilla more prominent in males + distance to anus bigger
Immunology and hematology (same as humans)
- Lymph vessels & nodes
- Spleen (50% bigger in males)
- Thymus: disappears at adult age
- NALT & MALT
Breeding and reproduction
Types of breeding
- Inbred strains: genetically similar due to long inbreeding (20x): almost homozygosity
- Outbred strains: selectively bred to create unique genetics: heterozygosity
- F1 hybrids: first line after breeding of 2 different inbred strains to create 100%
homozygosity
- Transgenic strains: introduction of DNA into genome
System for breeding
- Monogamous: 1 male + 1 female
- Polygamous: 1 male + several females (mostly trio)
- Success depends on age, genetics, vibration, noise, light…
- Sexual maturity: 6 – 8 weeks old
Estrus cycle
- Confirmation of successful mating: presence of vaginal plug instead of pregnancy
Role of pheromones
- Lee-boot effect: when female mice are bred w/o males their estrus cycles synchronizes
and gets supressed due to a lack of male pheromones
- Whitten effect: estrus cycles of these females can restart after contact with male odors
(eg urine).
- Bruce effect: recently bred females can abort their pregnancy after exposure to strange
males.
, Gestation and birth
- 19 à 21 days
- Non fertile mating => pseudopregnancy that can last 14 days (fake)
- Clear breast/mammal development: 14 days
- Pups are born blind and naked (6-12)
- Passive immunity: placenta and colostrum (first milk) up to 16 days
- Day 10: full hair over body + ears open
- Day 12: eyes open
- 14 days long solid food and water
Non-infectious pathologies
- Neoplasia: age and strain related (adenocarcinoma, lymphoma..)
- Bite wounds
- Ulcerative dermatitis (wet skin lesions)
- Barbering (overgrooming)
- Malocclusion (hypsodontia)
RAT
Introduction
- Rattus novergicus (Norway) or rattus rattus (Black)
- Low economics: short life and gestation + large litter/offspring
- Lot of inbred strains (easy genome manipulation), less GMO than mice
- Research topics: cancer, endocrine and auto-immune diseases…
Behaviour
- Very social (captivity not good)
- Very intelligent, less aggressive than mice and more easily trained
- Crepuscular: most active during twilight
- Routinely vocalize: aggression, stress, pleasure
- Activities: breeding, digging, next building…
- Complex communication system: sound (broader than mice) + olphactory
o Pheromones + proteins & sex hormones in urine as communication source
Anatomy and physiology
General
- Norway rat: small, thick ears and tail 85% of body length
- Black rat: long ears and tail longer than body
- Hair shaft: long or short
- Hypodont: teeth keep growing
- Olphactory and hearing: good
- Vision: not good (red light to perform night work during day cuz they can’t see it)
- Rat stressed? Excessive secretion of Harderian gland around eye leading to read tears
(=chromodacryorrhea)
Respiratory system
- 3 sections
, Anterior: nostrils, nasal cavities and nasopharynx
Intermediate: larynx, trachea and brochi
Posterior: left lung (1 lobe) and right lung (4 lobes)
- Slower breathing frequency than mice
Cardiovascular system
- Normal anatomy
- Exposure of heart to lateral thoracic left side
- Slower heart rate than mice
- Extra blood supply of atria
Gastro-intestinal system
- Omnivorous
- Coprophagy: eat feces bcs contains lots of bacteria (optimal nutritional activity)
- Weigh 250-500g + brown fat in neck region
- Rats cannot vomit! (due to missing nervous circuits, not bcs of divided stomach)
- No gallbladder
- Rib cage around liver
Urinogenital system
- Mammal: right kidney anterior to left
- Filtration area half as big compared to mice
- High concentrated urine (twice compared to humans)
- Females: 6 mammary glands throughout body, bicornate uterus, vaginal plate
degenerates and disappears
- Males: paired testes, highly developed accessory sex glands
- Sex determination: genital papilla more prominent in males + distance to anus bigger
- Hematology: males have more granulocytes and lymphocytes
Breeding and reproduction
System for breeding
- Monogamous: 1 male + 1 female
- Polygamous: 1 male + several females (mostly trio)
- Success depends on age, vibration, noise, light (continuous light can lead to persistent
estrus), diet (caloric restriction can stop estrus), temp (high temp can lead to male
infertility)
- Sexual maturity: 2-3 months old
Estrus cycle
- Confirmation of successful mating: presence of vaginal plug instead of pregnancy
Gestation and birth
- 21 à 23 days
- Implantation delayed with 3 to 7 days when lactating
- Maternal Abs cross yolk sac in utero (passive)
- Rarely pseudopregnancy
