Van Horn R N
Folia Primatol (Basel). 1975;24(2-3):203-20. doi: 10.1159/000155690.
Under natural light in Portland, Oreg., captive ring-tailed lemurs (Lemur catta) experience a breeding season that differs by nearly half a year from the season in Madagascar. A series of experimental day length changes from 1971 to 1974 demonstrated the ability of both temperate and tropical photoperiod cycles to induce estrous cycles in quiescent animals. After photoperiodic activation, most impregnated females failed to resume estrous cycles even after infant separations unless they received additional photoperiod changes. Unimpregnated females, on the other hand, showed no significant decline in the incidence of estrous cycles under prolonged exposure to a constant day length regimen (12.OL:12.OD) for over a year.
在俄勒冈州波特兰的自然光下，圈养的环尾狐猴（狐猴属）经历的繁殖季节与马达加斯加的季节相差近半年。1971年至1974年的一系列实验性日长变化表明，温带和热带光周期循环都有能力在静止的动物中诱导发情周期。在光周期激活后，大多数受孕的雌性即使在幼崽分离后也未能恢复发情周期，除非它们接受额外的光周期变化。另一方面，未受孕的雌性在长达一年多的时间里持续暴露于恒定日长方案（12小时光照：12小时黑暗）下，发情周期的发生率没有显著下降。
