Question

Is oocyte an egg?

Answer 1

Oocyte is the female germ cell involved in the reproduction process. It is developed within the follicle inside the ovaries. These germ cells produce a primordial germ cell which undergoes mitosis to form oogonia. The oogonia become primary oocytes during oogenesis. This primary oocyte is diploid in nature which undergoes meiosis II to produce secondary oocytes. The secondary oocyte forms into an ovum upon fertilization.

Complete answer:
There are two types of oocytes- primary and secondary. Primary oocytes are immature egg cells which undergo meiosis to form into an egg or ovum. The precursor of primary oocytes is the oogonia which is formed in the female fetus of four to eight weeks. The oogonia is diploid in nature. It is differentiated into primary oocytes through mitosis.
The primary oocytes will then undergo oogenesis in which they enter meiosis. They are arrested in prophase I stage of the first meiosis and remain in that stage until puberty begins. During the menstrual cycle, the primary oocytes start to develop in the ovarian follicle. It finishes its meiotic division and becomes a secondary oocyte.
The secondary oocyte is released from the mature follicle into the fallopian tube. This process is known as ovulation. In the meanwhile, the secondary oocyte has already started meiosis II and halted at the metaphase II stage. Secondary oocytes are called ovum or an egg. Upon fertilization, it fuses with sperm to form zygote.

Note:
It is important to note that the primary oocyte is not a mature egg. It undergoes meiosis I to form the secondary oocyte. The secondary oocyte will then undergo meiosis II and halts at the metaphase stage to form the mature egg or an ovum. The egg completes meiosis II only upon fertilization. If fertilization does not occur, it is disintegrated and released during menstruation.