Modes of estrus induction as a factor in studies of the reproductive behavior of rodents.
The choice of a mode of estrus for use in studies related to reproductive processes often is made arbitrarily. Females may be in hormone-induced estrus (HIE), cycling estrus (CE), male-induced estrus (MIE), or postpartum estrus (PPE). Although mode of estrus affects various aspects of copulatory behavior in different species in different ways, males mating with PPE females generally require more intromissions to reach ejaculation than with females in HIE or CE; males mating with females in CE generally attain more ejaculations than with PPE females. The duration of receptivity generally is shorter in PPE than in CE. Females in CE and PPE have different stimulus thresholds for pregnancy initiation, with the direction of the difference varying with the species. Among the other phenomena affected by mode of estrus are sperm competition, mate choice, and the Bruce effect. Because mode of estrus can be an important determinant of results, selection of a mode of estrus for any experiment should not be simply a matter of convenience. Further study of effects of mode of estrus is warranted.
Department of Psychology, University of Florida, Gainesville 32611.
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Dewsbury
D000818:Animals; D003307:Copulation / Q000502:physiology*; D004967:Estrogens / Q000494:pharmacology; D004971:Estrus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D049590:Postpartum Period; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011374:Progesterone / Q000494:pharmacology; D012377:Rodentia / Q000502:physiology* / Q000523:psychology*
D004967:Estrogens; D011374:Progesterone