98 • Alternatives to Animal Use in Research, Testing, and Education 
Table 5-2.— Some Anatomical, Physiological, and Metabolic Similarities and 
Differences Between Humans and Various Laboratory Animals (Continued) 
Conditions, systems, or structures 
Animal 
Similarities to humans 
Differences from humans 
Nonhuman primates . 
. Brain vasculature 
Intestinal circulation 
Placenta 
Pancreatic duct 
Adrenal gland 
Innervation 
Nucleic acid metabolism 
Teeth and mandible 
Brain 
Larynx 
Kidney 
Reproductive performance 
Menstrual cycle 
Spermatozoa 
Inguinal canal 
Rabbit 
.Splenic vasculature 
Spleen 
Immunity 
Innervation 
Middle ear and ear drum 
Liver 
Sweat glands 
Lung elasticity 
Rat 
.Spleen 
Senile splenic changes 
Senile pancreatic changes 
Cardiac circulation 
Abdominal circulation 
No gall bladder 
Sheep 
. Splenic vasculature 
Sweat glands 
Stomach and digestion 
Heat regulation 
Breeding 
Vomiting 
Sleep 
Plasma gamma globulins in 
newborn 
SOURCES: Adapted from B.M. Mitruka, H.M. Rawnsley, and D.V. Vadehra , Animals for Research, Models for the Study of Human 
Disease (New York: John Wiley & Sons, 1976); and W.l. Gay and J.D. Willett, “The Spectrum of Biological Systems 
and the Selection of Models," in National Symposium on Imperatives in Research Animal Use: Scientific Needs 
and Animal Welfare, NIH Pub. No. 85-2746 (Bethesda, MD: National Institutes of Health, 1985). 
• laboratory animals (e.g., mice, rats, guinea 
pigs, rabbits, hamsters, and ferrets); 
• nonhuman primates (e.g., baboons, new- 
world monkeys, and old-world monkeys); 
• exotic birds (e.g., parakeets, parrots, cock- 
atiels, and cockatoos); 
• birds of prey (e.g., falcons, hawks, and 
eagles); 
• freshwater and marine fish; 
• marine mammals (e.g., porpoises and whales); 
• large terrestrial mammals (e.g., deer, ante- 
lope, elk, lion, tigers, elephants, and llamas); 
and 
• assorted reptiles and amphibians. 
Choice of Species 
The variety of animal species used in research 
spans the animal kingdom, and some species are 
used more often than others (see ch. 3). Various 
reasons exist for using particular species in re- 
search: 
• Some species are more available than others. 
For example, certain primate species are in 
chronic short supply. Conversely, in the case 
of rats and mice, large numbers of commer- 
cial breeding businesses can supply particu- 
lar strains, ages, and sex on the purchaser’s 
demand. 
• Existing databases and literature have been 
built on a particular species. Additional work, 
in order to contribute to the field in a direct 
way, needs to be based on the same species. 
• For most research purposes, nonendangered, 
commercially available animals are preferred 
over endangered ones. 
• Some species exhibit the physiology or be- 
havior of interest in a more vivid and robust 
form than do other species. For example, the 
desert -adapted kangaroo rat is the species of 
