Spermatocytogenesis, Biology

Assignment Help:

SPERMATOCYTOGENESIS

In this process four spermatid develop from one PGC.

(i) Multiplication phase

  1. The spermotogonia or sperm mother cells lie next to the basement membrane.
  2. These divide repeatedly by mitosis producing new sex cells.
  3. Some of these cells move towards the lumen of the seminiferous tubule and enter the growth phase.
  4. These are called primary spermatocytes while others produced by the mitotic division of spermatogonia remain in the original condition and continue to produce new spermatogonia throughout the reproductive life of the animal.

(ii) Growth phase

  1. The spermatogonia, formed as a result of repeated divisions of the primordial germ cells, stop dividing and prepare themselves for maturation division.
  2. They increase in size by accumulating nourishing material obtained from germinal cells.
  3. The enlarged cells are known as primary spermatocytes.
  4. Initially, the nucleus of each primary spermatocyte is of ordinary size, but soot it imbides material and enlarges considerably.
  5. At the end of growth phase, when the primary spermatocyte is ready to undergo first maturation division (i.e. the reduction division) its nucleus is much larger than that spermatogonial cell.

(iii) Maturation phase

  1. Each diploid primary spermatocyte undergoes the first maturation division which is a reduction division, with its long drawn out and complicated prophase.
  2. The pairing and spliting of homologons chromosomes take place during zygotene and pachytene and this leads to the formation of tetrads. Due to crossing over, the exchange of homologus chromosomes also take place.
  3. According to some, all these chromosomal events are completed in the growth phase only, so that during first maturation division the chromosomes are equally distributed to the two daughter cells.
  4. As a result of reduction division, the two cells formed are haploid. These haploid cells are called secondary spermatocytes.
  5. The secondary spermatocytes undergo second maturation division which is a simple mitotic division.
  6. As a result, each secondary spermatocyte divides into two equal cells, called spermatids.
  7. In the end of maturation phase four haploid spermatids are formed from each, diploid primary spermatocyte.

Related Discussions:- Spermatocytogenesis

Agro industrial-animal wastes, Animal wastes Large quantities of anima...

Animal wastes Large quantities of animal wastes are available in the country but generally they are low in nutrient content with poor feeding value to the animals. However, po

Blastulation, Blastulation  Formation of blastula from morula is called...

Blastulation  Formation of blastula from morula is called as blastulation. During early cleavage the blastomere maintain spherical shape and mulberry like, this stage of emb

Define the maxillary tuberosity, Maxillary Tuberosity Incision and refl...

Maxillary Tuberosity Incision and reflection of the mucosa overlying the areas of the maxillary tuberosity and hamular notch when taking impressions for maxillary subperiosteal

Gene expression is controlled by chromatin state, Gene expression is contro...

Gene expression is controlled by chromatin state, _______ and _________. a. transcription factors and epigenetic regulators b. polymerases and control proteins c. delta and tau pro

Explain pasteurization - method of food preservation, Explain Pasteurizatio...

Explain Pasteurization (temperature below 100° C) - method of food preservation? Pasteurization is a heat treatment that kills a part but not all the microorganisms present and

Health stroke scale, Health Stroke Scale: Stroke is a leading cause of...

Health Stroke Scale: Stroke is a leading cause of death, hospitalization, disability and health care expenditure in U.S. (Fonarow G. et al., 2012).  Stroke is a medical condit

Criteria of essentiality, Criteria of Essentiality Amon and Stout as e...

Criteria of Essentiality Amon and Stout as early as 1939, suggested certain criteria that an element must fulfil in order to be classified as essential. These criteria are lis

Fundamental polymers of life, The synthesis of the three fundamental polyme...

The synthesis of the three fundamental polymers of life, DNA, RNA and protein, is template-directed. This means that - Answer A. the monomers are assembled one by one in a sequence

Filaments of a sarcomere in a skeletal muscle, Filaments of a sarcomere in ...

Filaments of a sarcomere in a skeletal muscle When the overlap between the thin and thick filaments of a sarcomere in a skeletal muscle is decreasing,    A. The total lengt

Symmetry - metazoa, Symmetry - Metazoa All living organisms have some ...

Symmetry - Metazoa All living organisms have some body shape and form. The general body plan of animals may be organized in one of several ways . Arrangement of parts or organ

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd