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

Define various methods of food processing, Define Various Methods of Food P...

Define Various Methods of Food Processing? In this unit, you studied the various methods of food processing. You learnt that food being most vital for the survival of human bei

Agro industrial-packaging, Packaging Compound feeds, whether in mash o...

Packaging Compound feeds, whether in mash or pellet form, are packed in bags or stored in bins. Bags may be filled directly from mixers, pellet coolers or holding bins and wei

What is the formation of atherosclerosis plaques, Which of the following le...

Which of the following leads to the formation of atherosclerosis plaques? -uptake of oxidized LDL particles by macrophase -non specific interactions between LDL particles

Bacteria classified according to their need for oxygen, How are bacteria cl...

How are bacteria classified according to their need for oxygen? According to their necessity of oxygen bacteria are classified into:- a) Anaerobic (those that survive withou

State the designations for horizons, State the Designations for Horizons  ...

State the Designations for Horizons  Of the several horizons, the master horizons are the results of the fundamental soil forming processes, viz. humification, eluviation  and

What is the excitation threshold of a neuron, What is the excitation thresh...

What is the excitation threshold of a neuron? How does this threshold relate to the "all-or-nothing" rule of the neural transmission? The excitation threshold of a neuron is th

Chromosomes in a cell, Two chromosomes in a cell have identical length and ...

Two chromosomes in a cell have identical length and centromere position yet are not homologous, what is different about them

Determine the meaning of response cost, Determine the meaning of Response c...

Determine the meaning of Response cost This is a type of punishment in which the subject has to return back the token (positive reinforcement) earned earlier if the subject dis

Determine the functions of vitamin c, Determine the Functions of Vitamin C?...

Determine the Functions of Vitamin C? The vitamin C is involved in several physiological and biochemical functions in the body. Ascorbate is the biochemically active form of t

Which terrestrial vertebrate group is extremely rare deserts, Which terrest...

Which terrestrial vertebrate group is extremely rare in deserts? The Amphibians are terrestrial vertebrates very rare in desert environments (although there are a few species a

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