Endocrinology of the Estrous Cycle. Estrous cycles give females repeated opportunities to become pregnant throughout their productive lifetime. The cycle is regulated by the hypothalamic-pituitary-gonadal axis, which produces hormones that dictate reproductive events.
What is the role of hormones in estrous cycle?
Hormones are commonly used to manipulate the estrous cycle. The major indications for hormonal control of estrus are to induce luteolysis, induce ovulation of a mature follicle, suppress estrus, induce cyclicity in anestrous animals, and superovulate cyclic animals.
What hormones are involved in the estrous cycle?
The estrous cycle is divided into three stages (follicular phase, estrus, and luteal phase) and is regulated by hormones secreted by the hypothalamus (GnRH), anterior pituitary gland (follicle stimulating hormone [FSH] and LH), ovary (estradiol and progesterone), and uterus (prostaglandin F2α [PGF2α]).
Why is estrous cycle important?
The estrous cycle represents the cyclical nature of ovarian activity that facilitates female animals to go from a period of reproductive receptivity to nonreceptivity ultimately allowing the establishment of pregnancy following mating.
How do the estrous and menstrual cycles compare?
In species with oestrous 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 hormone helps to maintain the pregnancy?
High levels of progesterone are required throughout pregnancy with levels steadily rising until the birth of the baby. During the first few weeks of pregnancy, progesterone produced from the corpus luteum (a temporary endocrine gland of the ovaries) is sufficient to maintain pregnancy.
What are the 4 phases of the estrous cycle?
The estrous cycle has four phases, namely proestrus, estrus, metestrus and diestrus and lasts for 4 to 5 days  (Table
What happens during the estrous cycle?
During estrous cycle, the reproductive tract is prepared for estrus or heat (the period of sexual receptivity) and ovulation (ovum release). The cycle is divided into four parts: proestrus, estrus, metestrus and diestrus.
What does estrous cycle mean?
: 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.
Which hormone is responsible for ovulation?
Luteinizing hormone (LH), the other reproductive pituitary hormone, aids in egg maturation and provides the hormonal trigger to cause ovulation and the release of eggs from the ovary.
Do humans go into heat?
Females of most vertebrate species exhibit recurring periods of heightened sexual activity in which they are sexually attractive, proceptive and receptive to males. In mammalian females (except Old World monkeys, apes and humans), this periodic sex appeal is referred to as ‘heat’ or ‘estrus’.
Why is it called in heat?
Estrus or “heat” is a period during the reproductive cycle when female animals become sexually receptive, signaling they are ready for mating. In most cases, this can also be referred to as “standing heat” because the female will stand to be mated by the male (Figure 1).
Why do they call it in heat?
The Romans considered that female mammals were driven mad by sexual desire. The term “estrus” describing female sexual heat is derived from the word “oestren” or gadfly. Cows race madly around their pastures to escape being bitten by the gadfly. A recent scholarly book argues that women also experience estrus.
How many estrous cycles are there per year?
In general, puberty occurs at 6-8 weeks when the estrous cycle commences each cycle is 4-5 days. The estrous cycle is polyestrous, more than one estrous cycle during a specific yearly time, with an estrous period of approximately 12 hours.