Introduction to common Laboratory Animals Division of Laboratory Animal Science.

RODENTIA 3 suborders A. Myomorpha- Mouse like (Rats, Mice, Hamsters etc.) B. Sciuromorpha - Squirrel like C. Caviomorpha- Guinea pigs, Capybara (Largest rodent-66kg)

Mouse- Mus musculus Class- Mammalia Order- Rodentia Chromosome number-(2n)- 40 Blood volume (ml/ 100 gram)- 6ml Olfaction highly developed. Poor vision Large S.A/ gram body weight- So dramatic physiologic changes in response to ambient temperature. Length of tail= L. of body

Contd. Heart rate= 300-800 bpm Body temp.- 36.5-38.0 deg C. WHITTEN Effect:- synchronisation of estrous of a group of females when a male is introduced. BRUCE Effect:- After a successful mating, within 24 hrs, if female is housed with a second male, implantation is prevented and comes to heat in 4-5 days.

Contd. LEE-BOOT Effect- Group of females housed together becomes anoestrous or pseudopregnant. STRAIN- Inbred colony STOCK- Outbred colony. Eg; of mice strains are- BALB/c, C57BL, C3H, nude/ Athymic mice etc. Mice are used in acute systemic toxicity studies, L.D.50, E.D.50 etc.

Rats- Ratus norwegicus 2n Chromosome number= 42. Thermoregulation centre matures 2 weeks after birth- Since then, Cuddling of new born animals. Rats regulates its own body weight and food intake. Strains Wistar came first – Wistar laboratories Sprague Dawley- From Wistar x Unknown wild by R.W.Dawley of Wisconsin.

Contd… Long Evans hooded- W x Wild male SHR- From Wistar Kyoto by truncation selection process. Rats are used in --------------------

Hamster- Mesocricetus auratus Chromosome number- (2n)- 44 Cheek pouches present- Tumour research Hibernation Short day, Low temp., Solitude, adequate food, nest etc. induces hibernation. Golden/Syrian hamster- Commonly used, Chinese hamster

Guinea pigs- Cavia porcellus. 2n Chromosome number is- 64 5th most used lab species (Mice>Rats>Birds>Fishes>Guinea pigs>G.P) Most fragile among lab animals Maximization sensitization tests

Rabbits- Oryctolagus cuniculus Stocks- Outbred New Zealand white, Soviet chinchilla, Silver fox etc. Pyrogen testing Intracutaneous irritation tests Bone implantations for orthopaedic implants

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