For conception to take place, a mature egg cell must be at the right place at the right time. When it is, a sperm penetrates an egg cell and fertilizes it. But before that can happen, the female body needs to produce eggs. Egg production is an essential part of the female reproductive system.
An egg cell, also called ovum (the plural is ova), is a female reproductive cell or gamete. Ova mature via oogenesis. Oogenesis is the creation of an egg cell.
Let’s start at the beginning. Ova are produced by the ovaries. FertilityFactor.com reports females usually have two ovaries, one on each side of the body, and they are found just outside of the uterus. The ovaries contain follicles that house immature eggs. Each month, roughly 20 follicles are stimulated and begin developing an egg.
An interesting fact is that all of a female’s ova are already present at birth.
According to a Cliff Notes article, egg cell production begins before birth, when about two million primitive cells known as oogonia accumulate in the ovaries. These oogonia are formed in the early stages of meiosis. (Meiosis is a type of cell division.)
The University of California at Berkeley Department of Molecular and Cell Biology says each phase of egg production takes place during specific periods. About seven million oogonia develop in the embryonic ovary as early as five months of gestation. Most of these cells then die, with about a half a million of them proceed through the first stage of meiosis.
After puberty, the oogonia develop into primary oocytes and then into egg cells at a rate of one per month. UC Berkeley adds that each is contained in a follicle of surrounding supporting cells.
These cells are called the Graafian follicle, which secretes female hormones called estrogens that regulate the development of secondary female characteristics. Egg cell development within the follicle requires approximately 14 days. The development is controlled by two hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Both hormones are secreted by the anterior lobe of the pituitary gland.
During the period of egg cell development, the female body is upping its supply of blood and nutrients in anticipation of a fertilized egg cell. On about the 14th day, ovulation (the release of the egg cell from the follicle) takes place. The egg cell is swept into the Fallopian tube and begins to move toward the uterus. After that, either the mature egg is fertilized or the woman enters the process of menstruation.
Sources:
Female Reproductive System. UC Berkeley Department of Molecular & Cell Biology. The Regents of the University of California. Web 25 Aug 2011.
http://mcb.berkeley.edu/courses/mcb135e/female.html
The Female Reproductive System. FertilityFactor.com. Web 25 Aug 2011.
http://www.fertilityfactor.com/infertility_taking_charge_female_reproductive_system.html
Female Reproductive Center. Cliff Notes by John Wiley & Sons, Inc. Web 25 Aug 2011.
http://www.cliffsnotes.com/study_guide/Female-Reproductive-System.topicArticleId-8741,articleId-8729.html
A Body Basics Article: Female Reproductive System. Kids Health by Nemours. Web 25 Aug 2011
http://kidshealth.org/parent/general/body_basics/female_reproductive_system.html#a_What_the_Female_Reproductive_System_Does
Oocyte. Biology Online by Web 25 Aug 2011.
http://www.biology-online.org/dictionary/Oocyte
Reviewed on August 25, 2011
by Maryann Gromisch
Edited by Jody Smith