Question

How many chromosomes are in the first polar body?

Answer 1

Hint: A polar body is formed as a result of oogenesis. Oogenesis is the process of production of egg cells from the ovaries of the female. The polar body is generally a haploid cell and does not have the ability to undergo fertilization.

Complete answer:
Oogenesis in humans starts with the development of primary oocytes through a process known as oocytogenesis. Oocytogenesis either completes before birth or shortly after birth. After the primary oocyte develops, it undergoes meiosis to form an ootid and this successive phase is termed as ootidogenesis. During oogenesis meiosis I as well as meiosis II takes place. Meiosis I of oogenesis begins during embryonic development and is found to halt in the diplotene stage of prophase I till puberty is reached. As a result of meiosis I, the primary oocyte develops into the secondary oocyte and a polar body. The secondary oocyte undergoes meiosis II which is also halted at metaphase II stage till fertilization. When meiosis II is completed it results in the formation of an ootid and a polar body. The function of the polar bodies is to discard any extra haploid set of chromosomes that might have resulted as a cause of meiosis. Both the polar bodies are found to disintegrate at the end of meiosis II. Since the polar bodies are haploid they contain 23 chromosomes.

Note:
Thus the function of the polar bodies is important as they help to maintain the chromosome number of the ootid and also make sure no haploid cells remain except the ootid which then undergoes maturation and develops into an mature ovum.