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

What is placoid scale. elaborate in detail., What is Placoid scale? Elabora...

What is Placoid scale? Elaborate in detail. Scales characteristic of cartilaginous fish. Formed from the dermis, scale is anchored in that layer by a basal plate composed of de

What is the principle of the design, In designing an experiment to find out...

In designing an experiment to find out whether light is required for photosynthesis    (a) what is the principle of the design    (b) what control would you use?

Essay, Need an essay in regard to an experiment that I did. Essay Assignm...

Need an essay in regard to an experiment that I did. Essay Assignment: Experimental Design Now that you have completed several hands-on lab experiments, take a little time to con

Endocrine system, Endocrine System The nervous system brings about in...

Endocrine System The nervous system brings about integration and co-ordination of several activities of the animal. The afferent stimuli from several sense organs are brought

What is the difference between an acid and a base, What is the difference b...

What is the difference between an acid and a base? Base is anything, which has a capability to abstract a proton. Using the easiest definition, an acid is something when add

Explain about myocardial infarction, Q. Explain about Myocardial Infarction...

Q. Explain about Myocardial Infarction? It is an initial acute phase of cardiovascular disease caused by the blockage of a coronary artery supplying blood to the. Heart shows t

Define the soybean protein isolates, Define the Soybean Protein Isolates? ...

Define the Soybean Protein Isolates? Soy protein isolates are the most pure and refined soy protein available. Isolated soybean proteins (ISP), or soybean protein isolates, are

Define the factors causing underweight - etiology, Define the Factors Causi...

Define the Factors Causing Underweight - Etiology? There are a number of factors causing underweight. These are: Poor selection of food Physical activity Mothe

State the term supply shortly, State the term supply shortly. Supply...

State the term supply shortly. Supply: Potential firms or businesses into the market which are willing and capable to supply various quantities of a good or service at a

What are prions? define concerns of food safety, Normal 0 false...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

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