oogônias

Oogonia are immature female germ cells. They are the primordial cells that give rise to oocytes, which eventually develop into mature ova or eggs. Oogonia are formed during early fetal development within the ovaries. They undergo a process called mitosis to increase their numbers, ensuring a sufficient supply for future reproduction.

Following their proliferation, oogonia enter meiosis, the specialized cell division process for sexual reproduction. However, this meiotic division is arrested at an early stage, specifically prophase I, and the cells are then referred to as primary oocytes. These primary oocytes remain in this state until puberty.

Upon reaching sexual maturity, hormonal signals trigger the resumption of meiosis. Typically, one primary oocyte per menstrual cycle will complete meiosis I, producing a larger secondary oocyte and a smaller polar body. The secondary oocyte then begins meiosis II, but is again arrested, this time at metaphase II. It is this secondary oocyte that is released during ovulation. Fertilization by a sperm cell is required to complete meiosis II, resulting in a mature ovum and another polar body. Oogonia are therefore essential for the production of eggs and, consequently, for female fertility.