Other species of non-primate vertebrates (eg rats, mice, horses, pig) females have a reproductive cycle called the estrous cycle (oestrous, British spelling). The primate (human, etc) equivilant is the menstrual cycle. Both cycles involve a complex and regular change in female anatomy and physiology over a defined time period.
Estrous Terms
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)
Early dioestrus (metoestrus)
Late dioestrus
Pro-oestrus
Oestrus
Wintermantel TM, Campbell RE, Porteous R, Bock D, Grone HJ, Todman MG, Korach KS, Greiner E, Perez CA, Schutz G, Herbison AE. Definition of estrogen receptor pathway critical for estrogen positive feedback to gonadotropin-releasing hormone neurons and fertility. Neuron. 2006 Oct 19;52(2):271-80. Using a mouse knock out model they have shown "...ovulation is driven by estrogen actions upon estrogen receptor alpha-expressing neuronal afferents to gonadotropin-releasing hormone (GnRH) neurons"
Diet Phytoestrogens "Plant-derived phytoestrogens have received much attention because of associated health benefits. Exposure of adult female mice to a commercial rodent diet with higher phytoestrogen levels facilitates uterine growth in the presence or absence of ovarian estrogen, alters uterine expression of estrogen-responsive genes, and advances the timing of implantation compared with a diet with lower phytoestrogen levels. Variability in phytoestrogen content in commercial rodent diets, both within and between brands, influences experimental results stresses the importance of this investigation and raises caution for investigators using rodents as animal models." Variation in commercial rodent diets induces disparate molecular and physiological changes in the mouse uterus. (PNAS 12 Jul 2005)
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.
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.
Data from table 1 : Determining the stage of the estrous cycle in the mouse by the appearance of the vagina. Champlin AK, Dorr DL, Gates AH. Biol Reprod. 1973 May;8(4):491-4.
"The feedback systems between the ovaries, uterus, hypothalamus and pituitary gland govern a cycle of events that takes 18-21 days. This is known as the oestrus cycle. 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."
Text from: Pig Oestrous Cycle
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 Oestrous cycle is Polyoestrous with an estrous period of approximately 12 hours.
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The Estrous (or Oestrous) cycle represents the type of female reproductive cycles in non-primate mammals.
Spelling Note: When searching both American (estrous) and British (oestrous) spellings are used in the literature (More? American and British Spelling Variations).
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