The estrous cycle (from Latin oestrus 'frenzy', originally from Ancient Greek οἶστρος (oîstros) 'gadfly') is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases, otherwise known as "rest" phases, or by pregnancies. Typically, estrous cycles repeat until death. These cycles are widely variable in duration and frequency depending on the species. Some animals may display bloody vaginal discharge, often mistaken for menstruation. Many mammals used in commercial agriculture, such as cattle and sheep, may have their estrous cycles artificially controlled with hormonal medications for optimum productivity. The male equivalent, seen primarily in ruminants, is called rut.
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👉 Estrous cycle in the context of Gelada
The gelada (Theropithecus gelada, Amharic: ጭላዳ, romanized: č̣əlada, Oromo: Jaldeessa daabee), sometimes called the bleeding-heart monkey or the gelada baboon, is a species of Old World monkey found only in the Ethiopian Highlands, living at elevations of 1,800–4,400 m (5,900–14,400 ft) above sea level. It is the only living member of the genus Theropithecus, a name derived from the Greek root words for "beast-ape" (θηρο-πίθηκος : thēro-píthēkos). Like its close relatives in genus Papio, the baboons, it is largely terrestrial, spending much of its time foraging in grasslands, with grasses comprising up to 90% of its diet.
It has buff to dark brown hair with a dark face and pale eyelids. Adult males have longer hair on their backs and a conspicuous bright red patch of skin shaped like an hourglass on their chests. Females also have a bare patch of skin but it is less pronounced, except during estrus, when it brightens and exhibits a "necklace" of fluid-filled blisters. Males average 18.5 kg (41 lb) and females average 11 kg (24 lb) in weight. The head-body length is 50–75 cm (20–30 in) with a tail of 30–50 cm (12–20 in).
- ⭐ Core Definition: Estrous cycle
- 👉 Estrous cycle in the context of Gelada
- Estrous cycle in the context of Animal sexual behavior
- Estrous cycle in the context of Endometrial
- Estrous cycle in the context of Progestogen
- Estrous cycle in the context of Estradiol
- Estrous cycle in the context of American pika
Estrous cycle in the context of Animal sexual behavior
Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity. Other sexual behaviour may be reproductively motivated (e.g. sex apparently due to duress or coercion and situational sexual behaviour) or non-reproductively motivated (e.g. homosexual sexual behaviour, bisexual sexual behaviour, cross-species sex, sexual arousal from objects or places, sex with dead animals, etc.).
When animal sexual behaviour is reproductively motivated, it is often termed mating or copulation; for most non-human mammals, mating and copulation occur at oestrus (the most fertile period in the mammalian female's reproductive cycle), which increases the chances of successful impregnation. Some animal sexual behaviour involves competition, sometimes fighting, between multiple males. Females often select males for mating only if they appear strong and able to protect themselves. The male that wins a fight may also have the chance to mate with a larger number of females and will therefore pass on his genes to their offspring.
Estrous cycle in the context of Endometrial
The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The functional layer thickens and then is shed during menstruation in humans and some other mammals, including other apes, Old World monkeys, some species of bat, the elephant shrew and the Cairo spiny mouse. In most other mammals, the endometrium is reabsorbed in the estrous cycle. During pregnancy, the glands and blood vessels in the endometrium further increase in size and number. Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus. The speculated presence of an endometrial microbiotahas been argued against.
Estrous cycle in the context of Progestogen
Progestogens, also sometimes written progestins, progestagens or gestagens, are a class of natural or synthetic steroid hormones that bind to and activate the progesterone receptors (PR). Progesterone is the major and most important progestogen in the body. The progestogens are named for their function in maintaining pregnancy (i.e., progestational), although they are also present at other phases of the estrous and menstrual cycles.
The progestogens are one of three types of sex hormones, the others being estrogens like estradiol and androgens/anabolic steroids like testosterone. In addition, they are one of the five major classes of steroid hormones, the others being the androgens, estrogens, glucocorticoids, and mineralocorticoids, as well as the neurosteroids. All endogenous progestogens are characterized by their basic 21-carbon skeleton, called a pregnane skeleton (C21). In similar manner, the estrogens possess an estrane skeleton (C18), and androgens, an androstane skeleton (C19).
Estrous cycle in the context of Estradiol
Estradiol (E2), also called oestrogen, oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of female reproductive cycles such as estrous and menstrual cycles. Estradiol is responsible for the development of female secondary sexual characteristics such as the breasts, widening of the hips and a female pattern of fat distribution. It is also important in the development and maintenance of female reproductive tissues such as the mammary glands, uterus and vagina during puberty, adulthood and pregnancy. It also has important effects in many other tissues including bone, fat, skin, liver, and the brain.
Estrous cycle in the context of American pika
The American pika (Ochotona princeps) is a small, herbivorous mammal of the family Ochotonidae, closely related to rabbits and hares (order Lagomorpha). It is native to the mountainous regions of western North America, typically inhabiting rocky slopes and talus fields at or above the tree line. Unlike most mammals of similar size, the American pika is diurnal, being active primarily during the day. It employs two distinct foraging strategies: directly consuming vegetation or gathering and storing plant materials in "haypiles" to sustain itself through the winter months, a behavior known as haying.
Pikas are vocal animals, using a variety of calls and songs both to warn of approaching predators and during the breeding season. Predators of the American pika include eagles, hawks, coyotes, bobcats, foxes, and weasels.