title: Reproductive biology and postnatal development of the neotropical climbing rat, Tylomys.
abstract: Neotropical climbing rats (Tylomys), offspring of animals from Mexico and Panama, were maintained in the Michigan State University Museum-Live Animal Colony for the purpose of collecting data on reproduction. Vaginal smears indicated an estrous cycle 6.8 +/- 0.4 da under natural winter lighting, 12.0 +/- 2.5 da when exposed to a 12:12 light:dark cycle, and 4.3 +/- 0.3 da when utilizing an activity wheel and under a 14:10 lighting scheme. The earliest recorded mating for a female Tylomys was 90 da of age. The gestation period was 40.6 +/- 0.5 da, and there was no statistical difference between the gestation lengths of lactating and non-lactating females. The average litter size was 2.3 with a range of 1-4. Weight at birth averaged 20.2 +/- 0.3 g, or about 8% (litter about 16%) the weight of the adult. The daily instantaneous rate of growth (weight) for the first wk was about 5.6%. Graphs were presented indicating changes with time of weight, total body length, and tail, hind foot, and ear lengths. Young respond to loud noises at 6-14 da of age, and eye opening occurs slightly later, at 7-15 da of age. The young cling tenaciously to the female's nipples nearly continuously for the first 3 wk. Females did not perform any nest-building activities. Weaning occurred at approximately 3-4 wk of age.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001724:Birth Weight; D001835:Body Weight; D004971:Estrus; D005123:Eye; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006128:Growth; D006197:Hair; D006309:Hearing; D008124:Locomotion; D008297:Male; D011247:Pregnancy; D051381:Rats / Q000254:growth & development / Q000502:physiology*; D012098:Reproduction; D012744:Sex Ratio; D012741:Sexual Maturation; D012880:Skin Pigmentation