proestrus

reproductive cycle

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July 13, 2026

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Proestrus is a phase in the reproductive cycle of female mammals, preceding estrus (heat). During proestrus, preparatory physiological changes occur, including the maturation of ovarian follicles under the influence of follicle-stimulating hormone. These follicles produce estrogen, which stimulates the thickening of the uterine lining (endometrium) in anticipation of potential fertilization. This period is crucial for preparing the female's body for mating and potential pregnancy.12

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dog
Reproductive cycle
The first stage is called proestrus. It begins with mild swelling of the vulva and a bloody discharge. This lasts for about 9 days, although it may vary by 2 or 3 days. During this phase the bitch may attract males, but she is not ready to be bred and…
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The first stage is called proestrus. It begins with mild swelling of the vulva and a bloody discharge. This lasts for about 9 days, although it may vary by 2 or 3 days. During this phase the bitch may attract males, but she is not ready to be bred and…
Read More

mammal
Estrus and other cycles
Estrus is preceded by proestrus, during which ovarian follicles mature under the influence of a follicle-stimulating hormone from the anterior pituitary. The follicular cells produce estrogen, a hormone that stimulates proliferation of the uterine lining, or endometrium. Following ovulation, in late estrus, the ruptured ovarian follicle forms a temporary…
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Estrus is preceded by proestrus, during which ovarian follicles mature under the influence of a follicle-stimulating hormone from the anterior pituitary. The follicular cells produce estrogen, a hormone that stimulates proliferation of the uterine lining, or endometrium. Following ovulation, in late estrus, the ruptured ovarian follicle forms a temporary…
Read More