MICROANATOMY

Detailed explanation-1: -Primordial germ cells migrate into the ovaries at week 4 of development and differentiate into oogonia (46, 2N). Oogonia enter meiosis I and undergo DNA replication to form primary oocytes (2N, 4C). All primary oocytes are formed by the fifth month of fetal life and remain dormant in prophase of meiosis I until puberty.

Detailed explanation-2: -In oogenesis, diploid oogonium go through mitosis until one develops into a primary oocyte, which will begin the first meiotic division, but then arrest; it will finish this division as it develops in the follicle, giving rise to a haploid secondary oocyte and a smaller polar body.

Detailed explanation-3: -Oogenesis begins when an oogonium (with the diploid number of chromosomes) undergoes mitosis to form primary oocytes (also with the diploid number of chromosomes). Oogenesis proceeds as a primary oocyte undergoes the first cell division of meiosis to form secondary oocytes with the haploid number of chromosomes.