Oogenesis
Eggs in ovaries halted before anaphase I meiosis I completed during maturation meiosis 2 completed after fertilization
Oogenesis is the process by which the female germ cells, or oocytes, develop into mature eggs capable of being fertilized by sperm. This process occurs within the ovaries of a female.
The process of oogenesis commences in the fetal period and continues through adulthood. During fetal development, the germ cells divide through mitosis to form millions of oogonia. However, only about 1-2 million oogonia survive until birth.
At puberty, the production of hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), stimulate the surviving oogonia to further develop into primary oocytes. These oocytes begin the first meiotic division but stall in prophase I until sexual maturity.
During each menstrual cycle, a few primary oocytes are selected to continue their development, and they grow into secondary oocytes. This is known as folliculogenesis, and also involves the development of a follicle surrounding the oocyte.
Once developed, a secondary oocyte is ovulated into the fallopian tube, where it can be fertilized by a sperm. If fertilized, the secondary oocyte completes the second meiotic division and forms a mature egg.
However, if the secondary oocyte is not fertilized, it undergoes apoptosis and is eliminated during menstruation.
In summary, oogenesis is a complex and continuous process that occurs within the ovaries of females. It involves the development of oogonia into primary and secondary oocytes, folliculogenesis, ovulation, and ultimately the formation of a mature egg capable of being fertilized by sperm.
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