Definition •Estrous cycle : reproductive cycle of female generally defined as period from one estrous to the next . It two phase •1- follicular phase(proestrus and estrus) •2- luteal phase (metestrus and diestrus)
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What is oestrous cycle in biology?
The oestrous cycle or estrous cycle (derived from Latin oestrus; "frenzy", originally from Greek οἶστρος, oîstros; "gadfly") is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females.
How long does an estrous cycle last?
Length of estrous cycle 21 day 22 day 17 days 21 days 21 days 15 -65 weeks 2 – 3 weeks (if no mated) Duration of estrous 24 (hours) 4 -7 days 36 hours (24 -48) 18 – 36 hours 48-72 hours 9 -10 days 3 -6 days Optimal breed time( hours after onset of estrous) 10 -16 48 -72 18 - 24 24 - 36 12 - 30 48 -96 During estrous
What is the meaning of Estral cycle?
: the correlated phenomena of the endocrine and reproductive systems of a female mammal from the beginning of one period of estrus to the beginning of the next — called also estral cycle, estrus cycle — called also estral cycle, estrus cycle
What is the difference between estrous and hair cycle?
estrous cycle the recurring periods of estrus in adult females of most mammalian species and the correlated changes in the reproductive tract from one period to another. hair cycle the successive phases of the production and then loss of hair, consisting of anagen, catagen, and telogen. Krebs cycle tricarboxylic acid cycle.
What is a estrous cycle simple definition?
Definition of estrous cycle : the correlated phenomena of the endocrine and reproductive systems of a female mammal from the beginning of one period of estrus to the beginning of the next. — called also estral cycle, estrus cycle.
What happens during estrous cycle?
The estrous cycle of the cow starts after puberty and occurs approximately every 21 days (17 to 24 days) except for pregnancy, reproductive disease or hormonal disorder. During estrous cycle, the reproductive tract is prepared for estrus or heat (the period of sexual receptivity) and ovulation (ovum release).
What is estrus cycle in biology?
estrus, also spelled Oestrus, the period in the sexual cycle of female mammals, except the higher primates, during which they are in heat—i.e., ready to accept a male and to mate. One or more periods of estrus may occur during the breeding season of a species.
What is the meaning of estrous?
Definition of estrus : a regularly recurrent state of sexual receptivity during which the female of most mammals will accept the male and is capable of conceiving : heat Some mares will exhibit estrus for 15 to 20 days.— Frederick Harper also : a single occurrence of this state.
What causes estrus?
As the follicle develops, estrogen is secreted by the ovary. The egg grows larger as more estrogen is secreted by the ovary. Estrogen causes estrus (“heat”) and contractions of the uterus to aid in transport of sperm.
What is the difference between menstrual and estrous cycle?
The key difference between estrous and menstrual cycle is that estrous cycle is the reproductive cycle of females of non-primate mammals in which the endometrium is reabsorbed by the walls of the uterus while menstrual cycle is the reproductive cycle of females of primate mammals in which endometrium is shed via ...
What is oestrus cycle with example?
Estrous cycle definition tells us that Estrous cycles usually repeat themselves before a woman dies. Bloody vaginal discharge in some species is sometimes confused for menstruation. Some of the oestrous cycle examples may include rats, mice, horses, pigs that tend to have this form of the reproductive cycle.
Why is estrus called heat?
In species with estrous cycles, females are generally only sexually active during the estrus phase of their cycle. This is also referred to as being "in heat". In contrast, females of species with menstrual cycles can be sexually active at any time in their cycle, even when they are not about to ovulate.
What is estrus in animals?
Estrus or “heat” is a period during the reproductive cycle when female animals become sexually receptive, signaling they are ready for mating.
What is an example of estrus?
Estrus is defined as the period of sexual heat in a female. An example of estrus is the period of time when a female animal is looking for a sexual mate. The period of this when the female will accept mating with the male, characterized by changes in the sex organs.
What are the 4 stages of estrus?
The estrous cycle has four phases, namely proestrus, estrus, metestrus and diestrus and lasts for 4 to 5 days [4] (Table 1).
Why is estrus so important?
The importance of estrus is that this is the period of time in the estrous cycle that the female is fertile and able to conceive when mating. In cattle the estrous cycle ranges from 17-24 days and estrus is considered day zero of the cycle. This is because it is the day that outward signs of the cycle are apparent.
What is the estrous cycle?
The estrous cycle (derived from Latin oestrus; "frenzy", originally from Greek οἶστρος, oîstros; "gadfly") is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females.
When do estrous cycles start?
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.
What is the difference between oestrous and menstrual cycles?
One difference is that animals that have oestrous cycles resorb the endometrium if conception does not occur during that cycle. Animals that have menstrual cycles shed the endometrium through menstruation instead. Another difference is sexual activity.
How long is the oestrous cycle of buffalo?
Buffalo have an oestrous cycle of about 22 to 24 days. Buffalo are known for difficult eostrus detection. This is one major reason for being less productive than cattle. During four phases of its oestrous cycle, mean weight of corpus luteum has been found to be 1.23±0.22g (metoestrus), 3.15±0.10g (early dioestrus), 2.25±0.32g (late dioestrus), and 1.89±0.31g (pro-oestrus/oestrus), respectively. The plasma progesterone concentration was 1.68±0.37, 4.29±0.22, 3.89±0.33, and 0.34±0.14 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±0.60 during the metestrus, early diestrus, late diestrus and proestrus/estrus, respectively.
What is the spelling of "estrus"?
In British and most Commonwealth English, the spelling is oestrus 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 it is in that particular part of the estrous cycle .
How long does a cat's oestrous cycle last?
Even within species significant variability can be observed, thus cats may undergo an oestrous cycle of 3 to 7 weeks. Domestication can affect oestrous cycles due to changes in the environment. For most species, vaginal smear cytology may be used in order to identify oestrous cycle phases and durations.
What is the term for the regression of the corpus luteum?
In the absence of pregnancy the diestrus phase (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 .
How long does a reproductive cycle last?
It occurs in adult female mammals and is only complete when pregnancy does not occur. It lasts from 5 to 60 days, dependent on species.
What is the Krebs cycle?
Krebs cycle tricarboxylic acid cycle. menstrual cycle see menstrual cycle. ovarian cycle the sequence of physiologic changes in the ovary involved in ovulation; see also ovulation and reproduction. reproductive cycle the cycle of physiologic changes in the reproductive organs, from the time of fertilization of the ovum through gestation ...
What is the estrous cycle?
The estrous cycle represents the cyclical pattern of ovarian activity that facilitates female animals to go from a period of reproductive receptivity to non-receptivity ultimately allowing the establishment of pregnancy following mating. The normal duration of an estrous cycle in cattle is 18–24 days. The cycle consists of two discrete phases: the luteal phase (14–18 days; met-estrus and di-estrus) and the follicular phase (4–6 days; pro-estrus and estrus). The luteal phase is the period following ovulation when the corpus luteum (CL) is formed, while the follicular phase is the period following the demise of the corpus luteum (luteolysis) until ovulation. During the follicular phase final maturation and ovulation of the ovulatory follicle occurs which leads to the release of an oocyte (the female gamete) into the oviduct allowing the potential for fertilization.
Why do estrous cycles stop during pregnancy?
Estrous cycles cease during pregnancy due to the prolonged presence of elevated progesterone from the CL, and placenta (in later pregnancy: ∼20% from approximately day 200). Following parturition estrous cycles recommence after a variable period of anestrus and anovulation.
What is the difference between follicular and luteal phases?
The luteal phase is the period following ovulation when the corpus luteum (CL) is formed, while the follicular phase is the period following the demise of the corpus luteum (luteolysis) until ovulation.
What hormones regulate the estrous cycle in cattle?
The estrous cycle in cattle is regulated by the hormones of the hypothalamus (gonadotrophin-releasing hormone; GnRH), the anterior pituitary (follicle-stimulating hormone; FSH and luteinizing hormone; LH), the ovaries (progesterone; P4, estradiol; E2, and inhibins), and the uterus (prostaglandin F2α; PGF; Figure 1 ). These hormones function through a system of positive and negative feedback to govern the estrous cycle. GnRH is a decapeptide that was first isolated from the hypothalamus of pigs. Its control of the estrous cycle is mediated via its actions on the anterior pituitary which regulates the secretion of the gonadotrophs, LH, and FSH. The pulsatile secretion of basal levels of GnRH from the tonic center of the hypothalamus and the preovulatory surge of GnRH from the surge center of the hypothalamus prevent the desensitization of the GnRH receptor on the gonadotroph cells of the anterior pituitary. After transportation of GnRH from the hypothalamus to the pituitary gland via the hypophyseal portal blood system, GnRH binds to its G-protein-coupled receptor on the cell surface of the gonadotroph cells. This binding releases intracellular calcium which activates intermediaries in the mitogen-activated protein kinases signaling pathway culminating in the release of FSH and LH from storage compartments in the cytoplasm. FSH is only stored in secretory granules in the cytoplasm for short periods of time, whereas LH is stored for longer periods during the estrous cycle (Farnworth, 1995).
Why does progesterone increase after ovulation?
Following ovulation, progesterone concentrations begin to increase due to the formation of the CL in which the granulosa and theca cells of the ovulated DF luteinize and produce progesterone in readiness for the establishment and maintenance of pregnancy and/or resumption of the estrous cycle .
How long does an ewe's estrus cycle last?
Length of season. The estrous cycle of ewes lasts 17 days and 21 days for the doe. It is common to leave the males in a minimum of 34–42 days to ensure that each female has had two periods of estrus.
Which hormones regulate the pulse frequency of the luteal phase?
GnRH and hence LH pulse frequency are regulated in a negative feedback mechanism by estradiol and progesterone during the luteal phase, while in the follicular phase there is a positive feedback of estradiol (in the absence of progesterone) from the preovulatory follicle inducing the GnRH, LH, and FSH surges.
What is the estrous cycle?
estrous cycle. The series of changes that occur in the female of most mammals from one period of estrus to another. The estrous cycle usually takes place during the period known as the breeding season, which ensures that young are born at a time when the chance of survival is greatest. The length of the cycle varies from species to species.
How to use the estrous cycle in a sentence?
How to use estrous cycle in a sentence. It almost mirrors the Buddhist cycle of life, death, and rebirth. Eventually, the mistletoe bush grows, blooms, and forms berries, and the cycle begins anew. The Newsroom aired its final episode on Sunday, already an eternity ago in news-cycle terms.
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Differences From the Menstrual Cycle
The regulatory hypothalamic system generates gonadotropin-releasing hormone in pulses, the pituitary gland which releases the follicle-stimulating hormone and luteinizing hormone, and the ovary itself which secretes sex hormones such as estrogens and progesterone, are all found in mammals.
Four Phases
When it comes to animals with an oestrus cycle, a four-phase terminology is being used.
Specific Species
Since coitus causes ovulation, a female cat in heat seems to have an estrus period of 14 to 21 days and is classified as an induced ovulator. In the domestic cat and other non-domestic animals, furthermore, spontaneous ovulation has been observed on many occasions.
Overview
The estrous cycle (from Latin oestrus 'frenzy', originally from Ancient Greek οἶστρος (oîstros) 'gadfly') is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. 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 dep…
Differences from the menstrual cycle
Mammals share the same reproductive system, including the regulatory hypothalamic system 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 functioning. One difference is that animals th…
Etymology and nomenclature
Estrus is derived via Latin oestrus ('frenzy', 'gadfly'), from Greek οἶστρος oîstros (literally 'gadfly', more figuratively 'frenzy', 'madness', among other meanings like 'breeze'). Specifically, this refers to the gadfly in Ancient Greek mythology that Hera sent to torment Io, who had been won in her heifer form by Zeus. Euripides used oestrus to indicate 'frenzy', and to describe madness. Homer used the word to describe panic. Plato also used it to refer to an irrational drive and to describe the soul "dri…
Four phases
A four-phase terminology is used in reference to animals with estrous cycles.
One or several follicles of the ovary start to grow. Their number is species-specific. Typically this phase can last as little as one day or as 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 experience vaginal secretions that could be bloody. The female is not yet sexually receptive…
Cycle variability
Estrous cycle variability differs among species, but 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. 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.
Frequency
Some species, such as cats, cows and domestic pigs, are polyestrous, meaning that they can go 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 be divided into short-day and long-day breeders:
• Short-day breeders, such as sheep, goats, deer and elk are sexually active in fall or winter.
Specific species
The female cat in heat has an estrus of 14 to 21 days and is generally characterized as an induced ovulator, since coitus induces ovulation. However, various incidents of spontaneous ovulation have been documented in the domestic cat and various non-domestic species. 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 …
See also
• Mating system
• Musth
• Neutering
• Progesterone-releasing intravaginal device
• Reproductive cycle