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

Tricuspid valve - heart, It is made up of three cusps, anterior, posterior ...

It is made up of three cusps, anterior, posterior and septal. The septal cusp is attached to the medial margin. The anterior cusp is attached to the superior-lateral part of the ma

Mechanism of fertilization, MECHANIS M OF FERTILIZATION - The process ...

MECHANIS M OF FERTILIZATION - The process of fertilization complete into 5 steps - 1 .      APPROACH OF SPERM TO OVUM For fertilization sperm & ova interaction is

Explain in details aerobic respiration, Explain in details Aerobic Respirat...

Explain in details Aerobic Respiration? The pyruvate produced in glycolysis is further broken down in most organisms. This process, called aerobic respiration, requires gaseou

Types of metamorphic changes, Types of Metamorphic Changes The proces...

Types of Metamorphic Changes The process of metamorphosis includes reactivation of the morphogenetic processes. The morphogenetic changes also the mode of causation of these

What are taenias, What are taenias? What are the diseases caused by them? ...

What are taenias? What are the diseases caused by them? Taenias, also called as tapeworms, are platyhelminth animals (flatworms). The major diseases caused by taenias are taeni

What are the inferior trophic levels, Can the amount of available energy in...

Can the amount of available energy in a given trophic level be larger than the available energy in inferior trophic levels? What does that condition means to the conformation of th

Integral membrane protein movement and distribution, Various proteins are f...

Various proteins are free to take a move laterally in the plane of the bilayer. One experiment used to represent this included fusing cultured mouse cells with human cells under ap

How to load glycogen, How to load glycogen? Over the past fifty years, ...

How to load glycogen? Over the past fifty years, the biggest breakthrough was the discovery of how to load glycogen and sophistication in the methods of glycogen loading. Nitro

What is etherification, What is Etherification The act or process of m...

What is Etherification The act or process of making ether; specifically, the process by which a large quantity of alcohol is transformed into ether by the agency of a small am

Forebrain - diancephalon, DIANCEPHALO N - Less visible. Occupies on...

DIANCEPHALO N - Less visible. Occupies only 1% of brain's volume. Its lumen is diocoel or III ventricle. Roof is epithalamus . On it pineal body is present. Fl

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