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

Which term describes study of animal behaviour, Which of the below terms de...

Which of the below terms describes study of animal behavior based on comparisons, observation of patterns, and consideration of environmental adaptations? Is it: a) Ethology (p

Sources of vitamin c, Sources of vitamin C It is found in many of th...

Sources of vitamin C It is found in many of the natural foods like fresh citrus fruits like limes, lemons and oranges are rich sources of vitamin C. The best and the chea

Discuss about electric field, Discuss about electric field The electric...

Discuss about electric field The electric field is a vector quantity whose magnitude is the force per unit charge and points in the direction of the force on the positive test

What is the natural habitat of e.coli, What is the natural habitat of E.col...

What is the natural habitat of E.coli? The E.coli was first recognized in the colon region of large intestine and so it was given the name "coli" (found in colon) they are coli

How much sds need for 50 ml, How much SDS do you need for 50 ml of a 20% SD...

How much SDS do you need for 50 ml of a 20% SDS solution in water(weight/ volume)? SDS is a solid.

What is the meaning of food exchanges, What is the meaning of Food Exchange...

What is the meaning of Food Exchanges Food exchanges mean grouping of foods in which the specified amount of all the food provides approximately equal amounts of carbohydrate,

Fundamental difference between protozoans and algae, What is the fundamenta...

What is the fundamental difference between protozoans and algae? The basic difference among protozoans and algae is the fact that protozoans are heterotrophs whereas algae are p

Explain the deficiency and toxicity of vitamin a, Explain the Deficiency an...

Explain the Deficiency and Toxicity of vitamin A? Who defines VAD as tissue concentrations of vitamin A low enough to have adverse health consequences even if there is no evide

What is physical activity ratio, What is Physical activity ratio? Physi...

What is Physical activity ratio? Physical activity ratio (PAR): The energy cost of an activity per unit of time (usually a minute or an hour) expressed as a multiple of BMR. It

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