Oogenesis
Oogenesis
Oogenesis (pronounced: oh-oh-genesis) is the biological process that leads to the formation of an ovum or egg cell in female organisms. The term is derived from the Greek words "oion" meaning egg and "genesis" meaning origin or creation.
Etymology
The term "Oogenesis" is derived from two Greek words, "oion" which means egg and "genesis" which means origin or creation. It was first used in the late 19th century to describe the process of egg cell formation in female organisms.
Process
Oogenesis involves several stages including the formation of oogonia, their transformation into primary oocytes, and the eventual development of a mature ovum. This process begins before birth in mammals and continues throughout the reproductive life of the female.
Stages
The stages of oogenesis include:
- Oogonia Formation: This is the initial stage where diploid stem cells called oogonia are formed within the developing ovaries.
- Primary Oocytes Formation: The oogonia undergo mitosis to form primary oocytes, which then enter meiosis but halt at the prophase stage of meiosis I until puberty.
- Secondary Oocytes Formation: At puberty, hormonal changes trigger the completion of meiosis I in one primary oocyte per menstrual cycle, forming a secondary oocyte and a smaller polar body.
- Ovum Formation: If fertilization occurs, the secondary oocyte completes meiosis II, forming the ovum and another polar body.
Related Terms
See Also
External links
- Medical encyclopedia article on Oogenesis
- Wikipedia's article - Oogenesis
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