Do Women Go Into Heat Like Other Animals

Ovulation cycle occurring in most mammalian therian females

For the biological genus proper name of the gadfly, see Oestrus (fly).

The estrous cycle (from Latin oestrus 'frenzy', originally from Ancient Greek οἶστρος (oîstros) 'gadfly') is the set of recurring physiological changes that are induced past reproductive hormones in nearly mammalian therian females.^[1] Estrous cycles start subsequently sexual maturity in females and are interrupted by anestrous phases, otherwise known equally "rest" phases, or past pregnancies. Typically, estrous cycles repeat until expiry. These cycles are widely variable in duration and frequency depending on the species.^[two] Some animals may display bloody vaginal discharge, often mistaken for menstruation.^[iii] Many mammals used in commercial agriculture, such as cattle and sheep, may have their estrous cycles artificially controlled with hormonal medications for optimum productivity.^{[4] [five]} Naturally, estrous cycles are complemented past a rutting period of male counterparts inside a species.^[2]

Differences from the menstrual cycle [edit]

Mammals share the aforementioned reproductive system, including the regulatory hypothalamic organization that produces gonadotropin-releasing hormone in pulses, the pituitary gland that secretes follicle-stimulating hormone and luteinizing hormone, and the ovary itself that releases sex hormones, including estrogens and progesterone.

However, species vary significantly in the detailed performance. I difference is that animals that have estrous cycles resorb the endometrium if formulation does non occur during that cycle. Animals that have menstrual cycles shed the endometrium through menstruation instead. Some other difference is sexual activity. In species with estrous cycles, females are generally only sexually active during the rut phase of their bicycle. This is also referred to equally being "in heat". In contrast, females of species with menstrual cycles can be sexually agile at whatsoever time in their cycle, even when they are not about to ovulate.

Humans have menstrual cycles rather than estrous cycles. They, different most other species, accept concealed ovulation, a lack of obvious external signs to betoken estral receptivity at ovulation (i.east., the power to become pregnant). Animals with estrous cycles often have unmistakable outward displays of receptivity, ranging from engorged and colorful genitals to behavioral changes similar mating calls.

Etymology and nomenclature [edit]

Estrus is derived via Latin oestrus ('frenzy', 'gadfly'), from Greek οἶστρος oîstros (literally 'gadfly', more figuratively 'frenzy', 'madness', among other meanings similar 'cakewalk'). Specifically, this refers to the gadfly in Aboriginal Greek mythology that Hera sent to torment Io, who had been won in her heifer grade by Zeus.^{[ citation needed ]} Euripides used oestrus to betoken 'frenzy', and to draw madness. Homer used the word to describe panic.^[6] Plato also used it to refer to an irrational drive^[7] and to describe the soul "driven and fatigued by the gadfly of desire".^[8] Somewhat more closely aligned to electric current meaning and usage of oestrus, Herodotus (Histories, ch. 93.1) uses oîstros to describe the desire of fish to spawn.^[9]

The earliest utilise in English was with a meaning of 'frenzied passion'. In 1900, it was first used to draw 'rut in animals; heat'.^{[10] [xi]}

In British and most Commonwealth English, the spelling is rut or (rarely) œstrus. In all English spellings, the noun ends in -us and the adjective in -ous. Thus in North American English, a mammal may be described as "in estrus" when information technology is in that particular role of the estrous cycle.

Iv phases [edit]

A four-stage terminology is used in reference to animals with estrous cycles.

Proestrus [edit]

One or several follicles of the ovary start to grow. Their number is species-specific. Typically this stage tin last equally fiddling as i day or equally long as three weeks, depending on the species. Under the influence of estrogen, the lining of the uterus (endometrium) starts to develop. Some animals may feel vaginal secretions that could be bloody. The female person is not yet sexually receptive; the old corpus luteum degenerates; the uterus and the vagina distend and fill with fluid, get contractile and secrete a sanguinous fluid; the vaginal epithelium proliferates and the vaginal cytology shows a large number of not-cornified nucleated epithelial cells. Variant terms for proestrus include pro-oestrus, proestrum, and pro-oestrum.

Oestrus [edit]

Heat or oestrus refers to the phase when the female is sexually receptive ("in heat"). Nether regulation by gonadotropic hormones, ovarian follicles mature and estrogen secretions exert their biggest influence. The female then exhibits sexually receptive behavior,^[12] a situation that may be signaled past visible physiologic changes. Heat is commonly seen in the mammalian species, including primates. This stage is sometimes called estrum or oestrum.

In some species, the labia are reddened. Ovulation may occur spontaneously in others. Especially amidst quadrupeds, a point trait of estrus is the lordosis reflex, in which the animal spontaneously elevates her hindquarters.

Controlled internal drug release devices are used in livestock for the synchronization of oestrus.

Metestrus or diestrus [edit]

This phase is characterized by the action of the corpus luteum, which produces progesterone. The signs of estrogen stimulation subside and the corpus luteum starts to class. The uterine lining begins to appear. In the absence of pregnancy the diestrus stage (also termed pseudo-pregnancy) terminates with the regression of the corpus luteum. The lining in the uterus is not shed, but is reorganized for the next cycle. Other spellings include metoestrus, metestrum, metoestrum, dioestrus, diestrum, and dioestrum.

Anestrus [edit]

Anestrus refers to the phase when the sexual cycle rests. This is typically a seasonal consequence and controlled past lite exposure through the pineal gland that releases melatonin. Melatonin may repress stimulation of reproduction in long-day breeders and stimulate reproduction in curt-24-hour interval breeders. Melatonin is thought to act by regulating the hypothalamic pulse activity of the gonadotropin-releasing hormone. Anestrus is induced by time of year, pregnancy, lactation, significant illness, chronic energy deficit, and perchance historic period. Chronic exposure to anabolic steroids may besides induce a persistent anestrus due to negative feedback on the hypothalamus/pituitary/gonadal axis. Other spellings include anoestrus, anestrum, and anoestrum.

After completion (or abortion) of a pregnancy, some species take postpartum estrus, which is ovulation and corpus luteum production that occurs immediately following the birth of the young.^[13] For example, the mouse has a fertile postpartum estrus that occurs fourteen to 24 hours following parturition.

Cycle variability [edit]

Estrous cycle variability differs amidst species, merely cycles are typically more frequent in smaller animals. Even within species significant variability can be observed, thus cats may undergo an estrous cycle of 3 to 7 weeks.^[fourteen] Domestication can affect estrous cycles due to changes in the environment. For most species, vaginal smear cytology may be used in order to identify estrous cycle phases and durations.^[fifteen]

Frequency [edit]

Some species, such as cats, cows and domestic pigs, are polyestrous, significant that they tin can get into heat several times per year. Seasonally polyestrous animals or seasonal breeders have more than one estrous cycle during a specific time of the year and can exist divided into brusk-day and long-mean solar day breeders:

• Short-day breeders, such as sheep, goats, deer and elk are sexually active in fall or winter.
• Long-twenty-four hours breeders, such as horses, hamsters and ferrets are sexually agile in leap and summer.

Species that go into heat twice per year are diestrous. Canines are diestrous.

Monestrous species, such as canids^[16] and bears, have only one breeding season per year, typically in jump to let growth of the offspring during the warm season to assistance survival during the next winter.

A few mammalian species, such as rabbits and cats, do not have an estrous cycle, instead being induced to ovulate by the act of mating and are able to conceive at most whatsoever arbitrary moment.

Generally speaking, the timing of estrus is coordinated with seasonal availability of food and other circumstances such as migration, predation etc., the goal being to maximize the offspring'due south chances of survival. Some species are able to change their estral timing in response to external weather.

Specific species [edit]

Cats [edit]

The female person cat in heat has an estrus of xiv to 21 days and is mostly characterized every bit an induced ovulator, since coitus induces ovulation. However, diverse incidents of spontaneous ovulation have been documented in the domestic cat and various non-domestic species.^[17] Without ovulation, she may enter interestrus, which is the combined stages of diestrus and anestrus, before reentering estrus. With the induction of ovulation, the female becomes pregnant or undergoes a non-pregnant luteal stage, also known as pseudopregnancy. Cats are polyestrous but experience a seasonal anestrus in fall and belatedly winter.^[eighteen]

Dogs [edit]

A female domestic dog is usually diestrous (goes into heat typically twice per year), although some breeds typically accept 1 or iii cycles per year. The proestrus is relatively long at v to 9 days, while the estrus may last 4 to xiii days, with a diestrus of 60 days followed by about 90 to 150 days of anestrus. Female dogs drain during estrus, which commonly lasts from 7–xiii days, depending on the size and maturity of the dog. Ovulation occurs 24–48 hours later on the luteinizing hormone peak, which occurs around the quaternary twenty-four hour period of estrus; therefore, this is the all-time time to begin breeding. Proestrus bleeding in dogs is common and is believed to be caused by diapedesis of red blood cells from the blood vessels due to the increase of the estradiol-17β hormone.^[19]

Horses [edit]

A mare may be in heat for four to ten days, followed by approximately xiv days in diestrus. Thus, a cycle may be short, totaling approximately iii weeks.^[20] Horses mate in spring and summer; autumn is a transition fourth dimension, and anestrus occurs during winter.

A feature of the fertility cycle of horses and other big herd animals is that information technology is usually afflicted by the seasons. The number of hours daily that calorie-free enters the eye of the beast affects the encephalon, which governs the release of certain precursors and hormones. When daylight hours are few, these animals "shut down", go anestrous, and do not go fertile. As the days abound longer, the longer periods of daylight crusade the hormones that activate the breeding cycle to exist released. As it happens, this benefits these animals in that, given a gestation period of about eleven months, it prevents them from having young when the common cold of wintertime would brand their survival risky.

Rats [edit]

Rats are polyestrous animals that typically have rapid cycle lengths of 4 to 5 days.^[21] Although they ovulate spontaneously, they practice not develop a fully functioning corpus luteum unless they receive coital stimulation. Fertile mating leads to pregnancy in this style, but infertile mating leads to a state of pseudopregnancy lasting about x days. Mice and hamsters have similar behavior.^[22] The events of the cycle are strongly influenced by lighting periodicity.^[10]

A gear up of follicles starts to develop nigh the end of proestrus and grows at a near abiding rate until the beginning of the subsequent rut when the growth rates advance eightfold. Ovulation occurs well-nigh 109 hours after the showtime of follicle growth.

Estrogen peaks at about 11 am on the 24-hour interval of proestrus. Betwixt then and midnight in that location is a surge in progesterone, luteinizing hormone and follicle-stimulating hormone, and ovulation occurs at near 4 am on the next heat twenty-four hours. The following day, metestrus, is called early diestrus or diestrus I. During this solar day, the corpora lutea grow to a maximal volume, achieved inside 24 hours of ovulation. They remain at that size for three days, halve in size earlier the metestrus of the adjacent bicycle so shrink abruptly before rut of the bicycle later on that. Thus the ovaries of cycling rats contain 3 different sets of corpora lutea at unlike phases of evolution.^[23]

Bison [edit]

Buffalo accept an estrous cycle of about 22 to 24 days. Buffalo are known for difficult oestrus detection. This is i major reason for being less productive than cattle. During four phases of its estrous wheel, mean weight of corpus luteum has been institute to be 1.23±0.22g (metestrus), iii.15±0.10g (early diestrus), 2.25±0.32g (late diestrus), and 1.89±0.31g (proestrus/heat), respectively. The plasma progesterone concentration was 1.68±0.37, four.29±0.22, 3.89±0.33, and 0.34±0.xiv ng/ml while mean vascular density (mean number of vessels/10 microscopic fields at 400x) in corpus luteum was 6.33±0.99, 18.00±0.86, 11.50±0.76, and 2.83±0.lx during the metestrus, early diestrus, late diestrus and proestrus/oestrus, respectively.^[24]

Cattle [edit]

Female cattle, also referred to every bit "heifers" in agriculture, will gradually enter standing heat, or "continuing heat," starting at puberty between 9 and fifteen months of historic period. The cow estrous bicycle typically lasts 21 days.^[5] Standing estrus is a visual cue which signifies sexual receptivity for mounting by male cattle. This beliefs lasts anywhere between 8 and thirty hours at a time.^[25] Other behaviors of the female during standing heat may change, including, merely not limited to: nervousness, swollen vulva, or attempting to mount other animals.^[25] While visual and behavioral cues are helpful to the male person cattle, estrous stages cannot be determined by the man centre. Rather, the stage can be estimated from the appearance of the corpora lutea or follicle composition.^{[26] [27]}

Estrous control [edit]

Due to the widespread use of bovine animals in agronomics, cattle estrous cycles have been widely studied, and manipulated, in an effort to maximize profitability through reproductive management.^[25] Much estrous command in cattle is for the purpose of synchronization, a practice or set of practices most often used by cattle farmers to control the timing and duration of estrus in large herds.^[4]

At that place is variation betwixt the available methods of cattle estrous synchronization. Treatment depends on herd size, specific goals for control, and budget.^[4] Some of the FDA-approved drugs and devices used to mimic natural hormones of the estrous wheel include, but are non express to, the following classes:

• Gonadorelin: At that place are currently five available gonadorelin products that are FDA-Approved.^[28] Normally, gonadorelin is used in conjunction with another estrous control drug (typically, prostaglandin).^{[28] [29]} This drug is used to mimic gonadotropin releasing hormone (GnRH) and may also exist used to treat ovarian cysts.^[5]
• Prostaglandin: Mimics the prostaglandin F2-alpha hormone released when no pregnancy has occurred and regresses the corpus luteum.^[5] This drug is used to accomplish more consequent results in artificial insemination.^[29]
• Progestin: Used to suppress heat and/or block ovulation.^[5] About ordinarily, it is administered via an intravaginal insert comparable to an IUD, which used in controlling menstrual periods.^[thirty] It is as well available equally a medicated feed, but this method is not yet approved for cattle crop synchronization.^[5]

In that location is variation between the bachelor methods of cattle estrous synchronization. Handling depends on herd size, specific goals for control, and budget.^[4]

Bovine estrous cycles may likewise be impacted by other bodily functions such as oxytocin levels.^[31] Additionally, heat stress has been linked to harm of follicular development, specially impactful to the commencement-wave dominant follicle.^[32] Future synchronization programs are planning to focus on the touch of rut stress on fertilization and embryonic death rates after artificial insemination.^[33]

Additionally, work has been washed regarding other mammalian females, such equally in dogs, for estrous control; However, there are yet to be any approved medications exterior of those commercially available.^[34]

Others [edit]

Estrus frequencies of some other notable mammals:

• Sheep: eighteen days
• Pig: 21 days
• Goat: 21 days
• Rabbit: variable
• Ass: 13 to 31 days (average 23)
• Elephant: sixteen weeks
• Wolf: ix days

See besides [edit]

• Mating arrangement
• Musth
• Neutering
• Progesterone-releasing intravaginal device
• Reproductive wheel
• Rut (mammalian reproduction)
• Sexual swelling

References [edit]

1. ^ Hill, M. A. (2021, April 6) Embryology Estrous Cycle. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Estrous_Cycle
2. ^ ^{a b} Bronson, F. H., 1989. Mammalian Reproductive Biology. University of Chicago Press, Chicago, IL, United states.
3. ^ Llera, Ryan; Yuill, Cheryl (2021). "Estrous Cycles in Dogs". VCA Hospitals . Retrieved April 6, 2021. {{cite web}}: CS1 maint: url-status (link)
4. ^ ^{a b c d} "Synchronizing Estrus in Cattle - How does estrus synchronization work?". Texas A&M AgriLife Extension Service . Retrieved 2021-03-22 .
5. ^ ^{a b c d due east f} Medicine, Eye for Veterinary (2021-03-05). "The Cattle Estrous Cycle and FDA-Canonical Animal Drugs to Command and Synchronize Oestrus—A Resource for Producers". FDA.
6. ^ Panic of the suitors in Homer, Odyssey, book 22
7. ^ Plato, Laws, 854b
8. ^ Plato, The Commonwealth
9. ^ Herodotus, Histories, ch. 93.1
10. ^ ^{a b} Freeman, Marc Eastward. (1994). "The Neuroendocrine control of the ovarian cycle of the rat". In Knobil, Due east.; Neill, J. D. (eds.). The Physiology of Reproduction. Vol. ii (second ed.). Raven Press.
11. ^ Heape, Due west. (1900). "The 'sexual season' of mammals and the relation of the 'pro-oestrum' to menstruum'". Quarterly Journal of Microscopical Science. 44: ane:70.
12. ^ Miller, Geoffrey (April 2007). "Ovulatory wheel furnishings on tip earnings past lap dancers: Economic prove for human estrus?" (PDF). Development and Human Beliefs (28): 375–381. doi:ten.1016/j.evolhumbehav.2007.06.002.
13. ^ medilexicon.com > postpartum estrus citing: Stedman'due south Medical Dictionary. Copyright 2006
14. ^ Griffin, Brenda (December 2001). "Prolific Cats: The Oestrous Wheel" (PDF). Compendium on Continuing Education for the Practicing Veterinarian. 23 (12): 1049–1056.
15. ^ Marcondes, F. K.; Bianchi, F. J.; Tanno, A. P. (November 2002). "Determination of the oestrous cycle phases of rats: some helpful considerations". Brazilian Periodical of Biology. 62 (4A): 609–614. doi:x.1590/S1519-69842002000400008. ISSN 1519-6984. PMID 12659010.
16. ^ Valdespino, C.; Asa, C.South. & Bauman, J.East. (2002). "Estrous cycles, copulation and pregnancy in the fennec fob (Vulpes zerda)" (PDF). Periodical of Mammalogy. 83 (one): 99–109. doi:x.1644/1545-1542(2002)083<0099:ECCAPI>2.0.CO;2.
17. ^ Pelican et al., 2006
18. ^ Spindler and Wildt, 1999
19. ^ Walter, I.; Galabova, One thousand.; Dimov, D.; Helmreich, Thou. (February 2011). "The morphological basis of proestrus endometrial haemorrhage in canines". Theriogenology. 75 (3): 411–420. doi:10.1016/j.theriogenology.2010.04.022. PMID 21112080.
20. ^ Aurich, Christine (2011-04-01). "Reproductive cycles of horses". Animal Reproduction Scientific discipline. Special Issue: Reproductive Cycles of Animals. 124 (3): 220–228. doi:10.1016/j.anireprosci.2011.02.005. ISSN 0378-4320. PMID 21377299.
21. ^ Hill, K.A. (2021, March eleven) Embryology Estrous Bike. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Estrous_Cycle
22. ^ McCracken, J. A.; Custer, Eastward. E.; Lamsa, J. C. (1999). "Luteolysis: A neuroendocrine-mediated consequence". Physiological Reviews. 79 (2): 263–323. doi:ten.1152/physrev.1999.79.2.263. PMID 10221982.
23. ^ Yoshinaga, K. (1973). "Gonadotrophin-induced hormone secretion and structural changes in the ovary during the nonpregnant reproductive cycle". Handbook of Physiology. Vol. Endocrinology Two, Part 1.
24. ^ Qureshi, A. Southward.; Hussain, M.; Rehan, S.; Akbar, Z.; Rehman, N. U. (2015). "Morphometric and angiogenic changes in the corpus luteum of nili-ravi buffalo (Bubalus bubalis) during estrous cycle". Pakistan Periodical of Agricultural Sciences. 52 (iii): 795–800.
25. ^ ^{a b c} Perry, George (2004). Salverson, Robin (ed.). "The Bovine Estrous Cycle" (PDF). SDSU Extension.
26. ^ Ireland, James J.; Murphee, R.50.; Coulson, P.B. (1980). "Accuracy of Predicting Stages of Bovine Estrous Cycle by Gross Advent of the Corpus Luteum". Journal of Dairy Science. 63 (1): 155–160. doi:10.3168/jds.s0022-0302(80)82901-8. ISSN 0022-0302. PMID 7372895.
27. ^ Ginther, O. J.; Kastelic, J. P.; Knopf, Fifty. (1989-09-01). "Composition and characteristics of follicular waves during the bovine estrous cycle". Beast Reproduction Science. twenty (iii): 187–200. doi:10.1016/0378-4320(89)90084-5. ISSN 0378-4320.
28. ^ ^{a b} Medicine, Center for Veterinary (2018-11-03). "Fertagyl® (gonadorelin acetate) - Veterinarians". FDA.
29. ^ ^{a b} "LUTALYSE® Injection (dinoprost injection)". world wide web.zoetisus.com . Retrieved 2021-04-06 .
30. ^ "Hormonal Control of Estrus in Cattle - Management and Nutrition". Veterinary Manual . Retrieved 2021-03-22 .
31. ^ Armstrong, D.T.; Hansel, William (1959). "Alteration of the Bovine Estrous Cycle with Oxytocin". Journal of Dairy Science. 42 (3): 533–542. doi:ten.3168/jds.s0022-0302(59)90607-one. ISSN 0022-0302.
32. ^ Wolfenson, D.; Thatcher, Westward. W.; Badinga, 50.; Savi0, J. D.; Meidan, R.; Lew, B. J.; Braw-tal, R.; Berman, A. (1995-05-01). "Effect of Rut Stress on Follicular Development during the Estrous Cycle in Lactating Dairy Cattle1". Biology of Reproduction. 52 (5): 1106–1113. doi:10.1095/biolreprod52.5.1106. ISSN 0006-3363. PMID 7626710.
33. ^ Santos, J. E. P; Thatcher, W. Due west; Chebel, R. C; Cerri, R. L. A; Galvão, K. N (2004-07-01). "The effect of embryonic death rates in cattle on the efficacy of estrus synchronization programs". Animal Reproduction Science. Research and Exercise Iii. 15th International Congress on Animal Reproduction. 82–83: 513–535. doi:10.1016/j.anireprosci.2004.04.015. ISSN 0378-4320. PMID 15271477.
34. ^ Kutzler MA. Estrous Bicycle Manipulation in Dogs. Vet Clin North Am Pocket-size Anim Pract. 2018 Jul;48(4):581-594. doi:x.1016/j.cvsm.2018.02.006. Epub 2018 April 27. PMID 29709316.

Further reading [edit]

• Spindler, R. E.; Wildt, D. E. (1999). "Circannual variations in intraovarian oocyte but non epididymal sperm quality in the domestic cat". Biology of Reproduction. 61 (1): 188–194. doi:10.1095/biolreprod61.1.188. PMID 10377048.
• Pelican, G.; Wildt, D.; Pukazhenthi, B.; Howard, J. G. (2006). "Ovarian control for assisted reproduction in the domestic cat and wild felids". Theriogenology. 66 (1): 37–48. doi:10.1016/j.theriogenology.2006.03.013. PMID 16630653.

External links [edit]

• Systematic overview
• Etymology
• True cat estrous cycle
• Equus caballus estrous wheel
• Dogs in Heat - FAQ
• Skloot, Rebecca (Dec 9, 2007). "Lap-dance Science". The New York Times Mag.

Source: https://en.wikipedia.org/wiki/Estrous_cycle

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