Estrous Cycle

Introduction

The estrous cycle (British spelling, oestrous) is the main reproductive cycle of other species females of non-primate vertebrates, for example rats, mice, horses, pig have this form of reproductive cycle. There are also a variety of different forms:

• Polyestrous Animals - Estrous cycles throughout the year (cattle, pigs, mouse, rat).
• Seasonally Polyestrous Animals - Animals that have multiple estrous cycles only during certain periods of the year (horses, sheep, goats, deer, cats).
• Monestrous Animals - Animals that have one estrous cycle per year (dogs, wolves, foxes, and bear)

Links: Estrous Cycle | Mouse Estrous Cycle | original page

Rat Estrous Cycle

One of the best characterised reproductive cycles, though different species of rats may differ in reproduction. In general, puberty occurs at 6-8 weeks when the oestrous cycle commences each cycle is 4-5 days.

The estrous cycle is Polyoestrous with an estrous period of approximately 12 hours.

Links: Rat Development | [PMID: 16195173] | PubMed- rat estrous cycle

Mouse Estrous Cycle

The mouse oestrus cycle is 4-6 days, with oestrus lasting less than 1 day. (More? Other Embryos- Mouse Estrous Cycle)

The oestrus cycle stops during lactation except for one oestrus 12-20 hours postpartum.

Determining the stage of the estrous cycle in the mouse by the appearance of the vagina.

• Estrous Diestrus - Vagina has a small opening and the tissues are bluish-purple in color and very moist.
• Proestrus - Vagina is gaping and the tissues are reddish-pink and moist. Numerous longitudinal folds or striations are visible on both the dorsal and ventral lips.
• Estrus - Vaginal signs are similar to proestrus, but the tissues are lighter pink and less moist, and the striations are more pronounced.
• Metestrus-1 - Vaginal tissues are pale and dry. Dorsal lip is not as edematous as in estrus.
• Metestrus-2 - Vaginal signs are similar to metestrus-1, but the lip is less edematous and has receded. Whitish cellular debris may line the inner walls or partially fill the Vagina.

Links: Mouse Estrous Cycle

Pig Estrous Cycle

The feedback systems between the ovaries, uterus, hypothalamus and pituitary gland govern a cycle of events that takes 18-21 days. If conception occurs this cyclic pattern is interrupted and pregnancy is maintained for approximately 114 days. Removal of the sucking stimulus at weaning triggers a new sequence of events.

Links: Pig Development

References

Articles

• Su P, Wu JC, Sommer JR, Gore AJ, Petters RM, Miller WL.    [See Related Articles] Conditional induction of ovulation in mice. Biol Reprod. 2005 Oct;73(4):681-7.
• Champlin AK, Dorr DL, Gates AH.    [See Related Articles] Determining the stage of the estrous cycle in the mouse by the appearance of the vagina. Biol Reprod. 1973 May;8(4):491-4.

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Cite this page: Hill, M.A. (2024, April 19) Embryology Estrous Cycle. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Estrous_Cycle

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G