Ovulation

Ovulation is the process of discharging a mature ovum (egg) from an ovary after a Graafian follicle - representing the final stage of follicular development before ovulation - has been formed.

Table of contents

1 Ovulation in humans 2 Ovulation in animals 3 See also

Ovulation in humans

\nIn humans, normal ovulation happens 14 days before the start of the next menstrual cycle. Some women can feel a slight pain in their lower abdomen, known as Mittelschmerz or "intermenstrual pain". In every menstrual cycle some ovarian follicles beginn maturation, but mostly only one will end as a Graafian follicle, growing rapidly under the influence of FSH and LH at the end of its developpement to a diameter of approximatly 15 mm, forming a "blister" on the surface of the ovary with a small spot without blood vessels, the "stigma". Encymatic processes and the growing pressure of its fluid-filled antrum lead to its rupture. By this time, the oocyte has undergone its first meiotic division, leading to two cells of very different size: the secondary oocyte - containing all of the cytoplasmatic material of both daughter-cells - and the first polar body. The second meiotic division follows at once without DNA-replication but will be arrested in the metaphase and will so remain until fertilization. The spindle apparatus of the second meitoc division appears at the time of Ovulation. If no fertilasation occurs, the oocyte will degenerate approximaly 24 hours after ovulation. At ovulation, the mucous membrane of the uterus - named as "functionalis" - has reached its maximum size , and so have the endometrial glands, althouhg they are still non-secretory. Knowing about the time of ovulation ist critical for all forms of "natural family planning".

Ovulation in animals

\nSome interesting aspects can be noted here:\n*Ovulation in camels is induced by male pheromones. In caravans without bulls female camels don't have an estrus.\n*In cats Ovulation is induced mechanically by the male.\n*Chickens have an ovulation allmost every day.\n*Marsupials show resting eggs after ovulation. \n

See also

\n*anovulatory cycle \n