Question

How many eggs does a female have during her lifetime?

Answer 1

Hint: The female ovary contains the eggs for the lifetime at the time of birth. They do not produce new eggs in their lifetime. The number of eggs declines every month. The female has only 25% of the eggs at the time of puberty.

Complete answer:
The ovary is the female reproductive part of the woman which contains eggs or the oocytes. In the third trimester the foetus develops oogonium by the process of oocytogenesis. It undergoes meiosis I and forms primary oocytes. It is complete before birth or shortly after birth. Around 1 to 2 million primary oocytes are contained in the ovary at the time of birth. After attaining puberty, the primary oocyte further divides to form the first polar body which degenerates and secondary oocyte which undergoes meiosis and forms a second polar body which degenerates an ovum.
Meiosis I was arrested at meiosis 1 for around 50 years. Every month an ovum is produced by the process of oogenesis. Till the time a female has attained puberty, 75% of the primary oocytes are being lost.
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So, we can say that the female has 1-2 million eggs at the time of birth for her lifetime and is left with around 30,000 eggs at the time of puberty.

Note –
The arrest is due to the lack of cell cycle proteins required for further division. The arrest is maintained at the time prophase I of meiosis by the help of a protein called cyclic AMP. The oocytes are surrounded by follicles which help in maintaining the arrest.