Multiplication Phase

Multiplication phase is the phase during gametogenesis.  During foetal development, certain cells in the germinal epithelium of the foetal ovary are larger than others. Mitosis causes these cells to divide, resulting in a couple of million egg mother cells or oogonia in each foetal ovary. After birth, no new oogonia are created or added. The oogonia multiply during mitotic divisions to create the main oocytes.

Multiplication Phase in Spermatogenesis

Primary spermatocytes go through the first cell division of meiosis to form secondary spermatocytes during spermatogenesis. These are haploid cells. Secondary spermatocytes then quickly complete the meiotic division to form spermatids, which are also haploid cells. The four haploid cells produced by meiosis develop a flagellum tail and a compact head piece to become mature sperm cells capable of swimming and fertilising an egg. The compact head, which has shed much of its cytoplasm, is essential in the creation of a streamlined shape. The centre section of the sperm, which connects the head to the tail, contains several mitochondria, which provide energy to the cell. The sperm cell effectively gives just DNA to the zygote.

Multiplication Phase in Oogenesis

The egg, on the other hand, not only provides the other half of the DNA, but also organelles, building blocks for substances such as proteins and nucleic acids, and other required resources. The egg, which is much larger than a sperm cell, contains practically all of the cytoplasm that a developing embryo will have during its first few days of life. As a result, oogenesis is a considerably more complicated process than spermatogenesis.Growth phase: During this phase, the diploid oogonium synthesis (yolk reserve food material) or vitelline in the cytoplasm increases in size and volume to create the primary oocyte. This is referred to as vitellogenesis.

The diploid spermatogonial cells of the seminiferous tubules divide frequently by mitosis to create a number of diploid spermatogonia. Only a few of them have started the growing phase, while the others are being held in reserve.

Spermatogenesis Multiplication phase: During this phase, primordial germ cells divide repeatedly, resulting in the formation of spermatogonia. Spermatogonia are diploid.

At sexual maturity, the undifferentiated primordial germ cells divide numerous times by mitosis to form a huge number of spermatogonia (Gr. sperma = seeds, gonos-generation). Spermatogonia (2N) is classified into two types: type A spermatogonia and type B spermatogonia. Type A spermatogonia act as stem cells, dividing to generate more spermatogonia. Spermatogonia are the progenitors of sperms.

Maturation phase: This phase consists of two consecutive divisions, meiosis I and meiosis II. Meiosis I is a reductional process that produces two unequal sized cells from each primary oocyte. One cell is typically referred to as an I polar body, while the other is referred to as a secondary oocyte.

They go through meiosis II, which results in the creation of four haploid cells, one of which is larger in size and is known as an ootid, and the other three are smaller and known as polar bodies. Finally, the ootid developed into a functioning ovum. So, by the completion of oogenesis, one functioning ovum and three polar bodies are created. These polar bodies will perish as they disintegrate.

Oogenesis: Oogenesis occurs during foetal development when endodermal cells from the yolk sac enter the ovaries and initiate oogenesis. These cells divide mitotically, creating undifferentiated germ cells known as oogonia or egg mother cells in the ovary. In humans, oogonia have 46 chromosomes, which are diploid. Oogonia multiply during mitotic divisions and generate ovigerous cords or pfluger egg tubes in animals.

In Multiplication phase: the germinal epithelium of seminiferous tubules produces primordial germ cells. Mitosis allows these cells to multiply again, producing a high number of spermatogonia. I Multiplication: Oogenesis begins during the foetal stage. Oogonia, the primordial germ cell, develops from stem cells by mitotic cell division. In mature ovaries, a primordial follicle contains a primary oocyte. The primary oocyte is also known as the ova mother cell, which finally produces ova.

Conclusion

Multiplication phase is the phase when cells divide via mitosis, creating a few million egg mother cells or oogonia in each foetal ovary. After birth, no new oogonia are created or added. The oogonia multiply during mitotic divisions to create the main oocytes. Phase of multiplication. Multiplication phase is the phase during gametogenesis.  During foetal development, certain cells in the germinal epithelium of the foetal ovary are larger than others. Mitosis causes these cells to divide, resulting in a couple of million egg mother cells or oogonia in each foetal ovary. After birth, no new oogonia are created or added. The oogonia multiply during mitotic divisions to create the main oocytes.