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

Ooplasmic determinants and somatic cell determination, Ooplasmic Determinan...

Ooplasmic Determinants and Somatic Cell Determination Eggs of tunicates go through typically mosaic development in which the various blastomeres become determined to follow th

How a sample contaiinng this isotope decay, Please help with the following:...

Please help with the following: 32P is an unstable isotope of phosphorus that has a half-life of 14.29 days. Atoms of this isotope undergo beta decay in which a neutron decays i

Fungi, Candida albicans, and Aspergillus species are the most common of the...

Candida albicans, and Aspergillus species are the most common of the many fungal organisms identified as causing IE. Fungal endocarditis arises in specific settings. Valve replace

What are the etiological agents of malaria, Q. What are the etiological age...

Q. What are the etiological agents of malaria? The etiological agents of malaria are protozoans of the genus Plasmodium. There are four different kinds of plasmodia that cause

Process of conducting system of the heart, Impulses reaching the AV node fr...

Impulses reaching the AV node from the atria are delayed a little as they pass through the trunk and crura. The impulses first reach the papillary muscles and their contraction clo

Define phospholipids, a) Lipoproteins are large molecular compounds that a...

a) Lipoproteins are large molecular compounds that are essential to the transport of cholesterol and triglycerides (TGs) within the blood. They contain a lipid core composed of TG

Explain the principle of development, Explain the Principle of Development ...

Explain the Principle of Development The final guiding principle is that assessment involves the measure of change, or development, across multiple levels of analysis. Developm

List the four objectives of counselling a diabetic patient, Q. List the fou...

Q. List the four objectives of counselling a diabetic patient? Objectives of Diabetes Counselling 1. Facilitating decision to start treatment and change life style 2.

Defone economic consequences of malnutrition, Defone Economic consequences ...

Defone Economic consequences of malnutrition? Figure explains the economic consequences of malnutrition. You would note from the Figure that the economic productivity of the in

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