What is oogenesis? Give a brief account of oogenesis.
Explanation Oogenesis is the process of production of ovum (egg cell). Oogenesis begins with a germ cell, oogonium. The cell undergoes mitotic divisions to produce primary oocyte. A secondary oocyte (haploid) and a polar body (haploid) are produced by the unequal meiosis of the primary oocyte. The secondary oocyte receives most of the cellular material and one half of the chromosomes, while the rest goes to the polar body. The polar body eventually dies. At the time of ovulation, the secondary oocyte reaches the fallopian tube. If the secondary oocyte gets fertilized, the cell undergoes a second meiotic division to produce a second polar body (haploid) and a fertilized egg (diploid), containing the chromosomes of the sperm and of the egg. Final Answer The gamete formed by spermatogenesis is a simple motile nucleus, whereas in case of oogenesis, the oocytes contain all the substances required for their nutrition and development.
