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

Formation of vegetative and generative cells, Formation of Vegetative and G...

Formation of Vegetative and Generative Cells The division of a pollen grain results in two unequal cells-the vegetative cell and the generative cell. The pollen grain is herea

Describe phosphorylated for atp formation, Q. What is compound that is phos...

Q. What is compound that is phosphorylated for ATP formation? What is resulting compound when ATP liberates energy? adenosine triphosphate or ATP is formed after the binding of

Function of promoter in transcription, Problem 1: How many different ty...

Problem 1: How many different types of RNAs are present? What is the function of Promoter in Transcription? Mention different types of RNAs Discuss function of Promot

Phanerophytes - classes of life form, Phanerophytes - Classes of Life Form ...

Phanerophytes - Classes of Life Form The perennating buds in this case are present on erect, negatively geotropic shoots, much above the ground. These buds are naked or least

What is defective colour vision, What is Defective Colour Vision Defect...

What is Defective Colour Vision Defective colour vision is often called colour blindness. The ability to appreciate one or more of the primary colours is lacking. This can be e

Explain right and left dominant circulation, Q. Explain Right and left Domi...

Q. Explain Right and left Dominant Circulation? Right Dominant Circulation: In 85 per cent of patients, the right coronary artery goes on to form the AV nodal artery, the poste

Explain the general characteristics of honey, A) General Characteristics ...

A) General Characteristics 1) It should be a well-ripened natural product. 2) It should be clear and visually transparent. 3) It should be extracted with the help of a

Blotting technique to detect particular specific proteins, Blotting method ...

Blotting method to detect particular one proteins Ans) Western blotting

What is the still retorts, What is the Still Retorts? Still Retorts are...

What is the Still Retorts? Still Retorts are used in canning plants for heating foods in glass containers or different sizes of cans. These retorts are usually cylindrical in s

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