Estrus (redirected from no visible estrus)

estrus

Period in the sexual cycle of female mammals, except the higher primates, during which they are in heat (ready to accept a male for mating). Some animals (e.g., dogs) have only one heat during a breeding season; others (e.g., ground squirrels) will come into heat repeatedly during the breeding season until impregnated. During estrus the female secretes pheromones that signal her receptivity to the males; her genital area may become swollen, and she may also give behavioral signals.

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oestrus (US), estrus, estrum

a regularly occurring period of sexual receptivity in most female mammals, except humans, during which ovulation occurs and copulation can take place; heat

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estrus [′es·trəs]

(physiology)

The period in female mammals during which ovulation occurs and the animal is receptive to mating.

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Estrus

The period in mammals during which the female ovulates and is receptive to mating. It is commonly referred to as rut or heat. From one estrus period to the next there occurs a series of changes, particularly in the ovary, uterus, and vagina, termed the estrous cycle. With reference to the ovary, the cycle can be divided into a follicular phase, during which the Graafian follicles are ripening, and a luteal phase, during which the corpora lutea develop in the ovulated follicles. During these two phases, mainly estrogen and progesterone, respectively, are secreted, and these hormones control the uterine and vaginal changes. The beginning of the follicular phase is termed proestrus, and the luteal phase metestrus. Following the latter, there is a period of relatively little change, termed diestrus. In species in which the latter is prolonged, it is termed anestrus. See Estrogen, Reproduction (animal)

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Estrus 

(also heat or rut), a stage in the sex and reproductive cycle, or period of sexual activity, in female mammals. Estrus recurs regularly before coitus at intervals characteristic for each species of animal—several days, weeks, or months. During estrus the mating instinct is aroused, and in most mammals ovulation occurs at the end of estrus. In polyestrous animals, estrus recurs periodically throughout the year. In mice and rats, for example, it occurs every four to six days; in guinea pigs, every 18 days; and in cows, every 21 days. In monestrous animals, it occurs once or twice a year, as in dogs and foxes. During estrus, morphological changes occur in the vagina and uterus; they are especially marked in such rodents as mice, rats, and guinea pigs.