Introduction
The maturation phase is preceded by meiotic division. The main oocyte’s maturation division differs substantially from the spermatocyte’s maturation division. The cytoplasm of the oocyte divides unequally after meiotic division of the nucleus to generate a single big haploid egg and three little haploid polar bodies or polocytes at the end. This kind of asymmetrical split is really important to the egg. If the parent oocyte had been divided evenly, the stored nourishment would have been given equally to the four daughter cells, which could have been insufficient for the developing embryo. As a result of these unequal divisions, one of the four daughter cells has the majority of the cytoplasm and reserves enough food material for the growing embryo.
Maturation phase in spermatogenesis
Spermatogenesis is the process through which sperms are formed. Oogenesis, on the other hand, is the process by which eggs are formed. Furthermore, both oogenesis and spermatogenesis involve the same stages of sequential modifications, which include:
Stage of multiplication
Phase of growth
Phase of Maturity
Spermatogenesis’ Maturation Phase This results in two sequential divisions of the original spermatocyte. These are referred to as maturation divisions, with meiotic being the first. As a result, the primary spermatocyte divides into two secondary spermatocytes, which are haploid daughter cells. Furthermore, both secondary spermatocytes go through a second maturation separation, which is a normal mitotic division. As a result, four haploid spermatids are produced.
Spermatogenesis is the process through which sperms are produced. It can be found in the testicular seminiferous tubules. Germinal epithelial cells line the seminiferous tubules. The germinal epithelium is made up primarily of cuboidal primary or primordial germ cells (PGCs), as well as some tall somatic cells known as Sertoli cells (= nurse cells). Spermatogenesis is the process through which spermatids and spermatozoa are produced.
Maturation Phase in Oogenesis
Each initial oocyte, like a primary spermatocyte, goes through two meiotic divisions. However, the outcomes of maturation divisions in oogenesis differ markedly from those in spermatogenesis. The primary oocyte divides into two significantly unequal haploid daughter cells during the first meiotic division: a huge secondary oocyte and a small first polar body or polocyte.
The first polar body may split to generate two second polar bodies during the second maturation division. The secondary oocyte divides once more, this time into unequal daughter cells, a large ootid and a very small second polar body. The ootid develops into a viable haploid ovum. One oogonium, one ovum, and three polar bodies are thus generated from a single oogonium. The female gamete is known as the ovum. Polar bodies don’t reproduce and so degrade quickly.
In the secondary oocyte stage, the ovum is discharged from the ovary. The secondary oocyte matures in the mother’s oviduct (Fallopian tube) after the sperm has entered it for fertilisation.
The initial polar body in humans (and most vertebrates) does not go through meiosis II, whereas the secondary oocyte does. However, it then stops progressing and waits for sperm to arrive to
I The first division of maturation:
The homologous chromosomes of the primary oocyte nucleus undergo pairing or synapsis, duplication, chiasma formation, and crossing over during the first maturation division or first meiosis. Soon after, the nuclear membrane ruptures, causing bivalent chromosomes to shift to opposing poles due to chromonemal fibre contraction.
The endoplasmic reticulum creates a new nuclear envelope around each daughter chromosome. Unequal cytokinesis occurs following karyokinesis, resulting in the formation of a small haploid polar body or polocyte and a large haploid secondary oocyte or ootid.
The oocyte’s nucleus passes through two maturation divisions during the maturation phase. The first division is meiotic, which results in the formation of two haploid (n) cells. The cytokinesis in this division is uneven; the secondary oocyte is formed by a big daughter cell with practically all of the cytoplasm and yolk. The smaller one, which has a haploid nucleus (n) but very little cytoplasm, forms the first polar body, which is released from the oocyte’s surface near the animal pole. The secondary oocyte with haploid chromosomes goes through a second maturation division, often known as a meiotic division. This is also an unequal partition. The giant cell, which contains the yolk, is referred to as the ovum, while the little cell is referred to as the second polar body. The first polar may also divide in this way, resulting in three polar bodies that degenerate quickly. As a result of oogenesis, each primary oocyte produces just one functioning ovum. The first meiotic division happens when the growth phase begins in most vertebrates, and the second maturation division occurs when the egg is activated by the arrival of sperm.
Conclusion
Gametogenesis is the process through which male and female sex cells or gametes, i.e., sperms and eggs, are created in the male and female gonads, respectively (testes and ovaries). The nuclei of gametes vary from the nuclei of all other cells (= somatic cells) in that they contain half the number of chromosomes seen in somatic cell nuclei.