Ovulation

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Ovulation is part of the femal menstrual cycle and is the process by which a mature ovarian follice, which is part of the ovary, discharges an egg which then travels down the fallopian tube where it is available for fertilisation by a sperm. The secretion of unidentified chemical signals from a group of cells called the granulosa cells secrete unidentified chemical signals that attract sperm to the egg. This ovulation process normally occurs between the 10th and 19th days of the cycle and varies from female to female[1].

During ovulation the walls of the uterus thicken, in preperation for a fertilised egg, however if the egg is not fertilised then this lining is not needed and therefore breaks down. The breakdown of the uteras walls causes the monthly bleeding of a menstrual period.

Control

Ovulation is controlled by the hypothalamus in the brain which sends signals to the pituitary gland which cause it to secrete luteinizing hormone, commonly known as LH, and also follicle-stimulating hormone, commonly known as FSH. It is these hormones that cause the release of the egg from the ovaries.

The Phases

We can split the process of ovulation into three phases and they are stated and explained below:

  1. Periovulatory: in this stage the uterus lining thickens as the cells that surrounds the ovum become more like mucous and therefore expand
  2. Ovulatory: in this stage an enzyme is secreted which creates a hole from which the eggs can leave and therefore enter the fallopian tube where fertlisation can occur
  3. Postovulatory: this is the point where the hypothalamus causes the release of the LH and FSH hormones and a fertilised egg will enter the womb or an unfertilised egg will lead to the stopping of this hormone release and therefore the break down of the uterus walls [2].

References

  1. Chapter 21-SexfckLRThe Molecular Biology of the Cell Fifth EditionfckLRBruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walter
  2. www.medicalnewstoday/articles/150870.php
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