RESUMO
The effect of food restriction on reproductive development was compared in male and female mice. This was accomplished using an experimental design that allowed us to assess the amount of reproductive development that could occur in the total absence of body growth, when growth was stopped at each of three different body weights. Our results demonstrate that reproductive development has much more inertia in males than in females. Specifically, the final stages of reproductive development can proceed largely independently of body growth in males but not in females. This same design was also employed in an abbreviated study of male rats. When its results are coupled with the existing literature for female rats, it appears as though the sex differences noted above are characteristic of both species.
Assuntos
Privação de Alimentos , Genitália Feminina/crescimento & desenvolvimento , Genitália Masculina/crescimento & desenvolvimento , Animais , Peso Corporal/efeitos dos fármacos , Gonadotropina Coriônica/farmacologia , Feminino , Genitália Feminina/anatomia & histologia , Genitália Masculina/anatomia & histologia , Gonadotropinas Equinas/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos , Tamanho do Órgão/efeitos dos fármacos , Ovulação/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Testosterona/farmacologiaRESUMO
Reproductive development was examined in wild house mice who had either unlimited or severely restricted access to food. The degree of food restriction was set at a level that allowed no body growth after 24 days of age. This treatment completely blocked reproductive development in females. In contrast, it had only minor effects on the reproductive development of males. Despite their stunted condition, food-restricted males developed normal numbers of sperm in their testes and vasa deferentia. They developed almost normal accessory tissues, and 8 of 10 inseminated test females when challenged at 8 wk of age. These results are considered primarily in relation to the opportunistic reproductive strategy of this species.
Assuntos
Privação de Alimentos/fisiologia , Reprodução , Animais , Peso Corporal , Feminino , Masculino , Camundongos , Tamanho do Órgão , Ovário/crescimento & desenvolvimento , Glândulas Seminais/crescimento & desenvolvimento , Fatores Sexuais , Comportamento Sexual Animal/fisiologia , Contagem de Espermatozoides , Testículo/crescimento & desenvolvimento , Útero/crescimento & desenvolvimentoRESUMO
Cortisol and aldosterone levels were measured in plasma of eastern cottontail rabbits (Sylvilagus floridanus) collected by three different methods, i.e., shooting, live-trapping and falconry. Cortisol levels ranged from near 0 to 27.5 micrograms/100 ml and aldosterone from near 0 to 220 ng/100 ml. Shot animals had significantly lower cortisol concentrations than those taken by either of the other methods. Trapped cottontails also had significantly lower aldosterone levels.
