Introduction:
Spermatogenesis refers to the process through which males generate sperm from immature germ cells. It occurs in seminiferous tubules of the testes. During spermatogenesis, a diploid spermatogonium (male germ cell) develops into a diploid primary spermatocyte. This diploid primary spermatocyte undergoes its first meiotic division (meiosis I), which is a reductional division that produces two equal haploid secondary spermatocytes. Each secondary spermatocyte undergoes the second meiotic division (meiosis II), which results in the creation of two equal haploid spermatids. A diploid spermatogonium produces four haploid spermatids as a result of this. Spermatids are transformed into spermatozoa during the process of spermiogenesis (sperm).
Process of Spermatogenesis:
Spermatogenesis is the process by which sperm with half the number of chromosomes as somatic cells are produced (haploid). It can be discovered in seminiferous tubules. Sperm production begins at puberty and continues throughout life, with hundreds of millions of sperm produced every day. The epididymis is where sperm develops and is kept once it is formed. During the process of spermatogenesis, each spermatogonium produces four sperms. Multiplication, growth, maturation, and spermiogenesis are the stages of spermatogenesis. During the multiplicative phase, the sperm mother cells split through mitosis to generate spermatogonia.
During the development phase, spermatogonia grow in size to produce large primary spermatocytes with the help of Sertoli cells. The maturation phase includes meiosis I, during which primary spermatocytes divide to become secondary spermatocytes, and meiosis II, during which spermatids are produced. As a result, each primary spermatocyte generates four haploid spermatids. Spermiogenesis or spermateliosis is the process through which flagellated spermatozoa develop from spermatids. Spermiogenesis begins in the seminiferous tubules and progresses to the epididymis.
Mammalian Spermatogenesis:
Mammalian spermatogenesis is a highly synchronized, regular, lengthy, and extremely complex process in which a spermatogonial “stem cell” eventually transforms into a highly differentiated haploid cell known as a “Spermatozoon.”
Spermatogonia, spermatocytes, and spermatids, which are generally organized in concentric layers in the seminiferous tubules, are all implicated in this differentiation.
In adult animals, spermatogenesis is a continuous process that can be divided into two phases, each of which is distinguished by distinct morphological and biochemical changes in nuclear and cytoplasmic components.
Stages of Spermatogenesis:
The two processes are spermatogenesis (mitosis and meiosis) and spermiogenesis.
There are three stages to this stage of spermatogenesis.
- Spermatogonia proliferation and renewal are terms used to describe the multiplication phase. The diploid spermatogonia at the margin of the seminiferous tubule proliferate mitotically to form spermatocytes and also to give rise to more spermatogonia! stem cells and begin the growth phase during this phase.
- Growth phase: During this phase, spermatogonia double in volume and become primary spermatocytes, which are still diploid in number. These primordial spermatocytes are now ready for maturation.
The primary spermatocyte enters the prophase of the meiotic or maturation division. Meiotic prophase is a complex process characterized by an organized collection of chromosomal rearrangements and molecular changes. During meiosis, the original nuclear DNA replicates, each homologous chromosome begins pairing (synapsis), and longitudinally separates into two chromatids joined by a centromere.
Some chromosome material is exchanged (crossed over) between two non-sister chromatids of each homologous pair (tetrad) by producing a chiasma, allowing for basically limitless diversity in paternal and maternal gene pairs in any gamete.
- Finally, two chromosomes (tetrads) from each homologous pair go to the opposing poles of the primary spermatocyte. Each primary spermatocyte pole now has a haploid chromosomal pair. Each set of chromosomes is surrounded by the nuclear membrane, which forms from the endoplasmic reticulum. The first meiotic division is usually followed by cytoplasm division (cytokinesis), which divides each main spermatocyte into two haploid, secondary spermatocytes.
Conclusion:
Therefore, in this unit, we learned about spermatogenesis, its process, and the steps involved. We got to know that spermatogenesis refers to the process through which males generate sperm from immature germ cells. It occurs in seminiferous tubules of the testes. During spermatogenesis, a diploid spermatogonium (male germ cell) develops into a diploid primary spermatocyte. This diploid primary spermatocyte undergoes its first meiotic division (meiosis I), which is a reductional division that produces two equal haploid secondary spermatocytes. Each secondary spermatocyte undergoes the second meiotic division (meiosis II), which results in the creation of two equal haploid spermatids. A diploid spermatogonium produces four haploid spermatids as a result of this. Spermatids are transformed into spermatozoa during the process of spermiogenesis (sperm).