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 are the antigen-respective antibodies abo blood group, What are the an...

What are the antigens and the respective antibodies of the ABO blood group system? The ABO blood system contain the erythrocytic antigens A and B that can be attacked by the an

Flame cells, where are flame cells present?

where are flame cells present?

Define the effects of dietary fibre, Define the Effects of Dietary Fibre? ...

Define the Effects of Dietary Fibre? After reviewing the properties of fibre, we will now study various physiological effects of fibre, as it passes through the gut. The effect

Explain fermented vegetable foods, Normal 0 false false fal...

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

Cycles of matter, describe the path of nitrogen through its biogenochemicsa...

describe the path of nitrogen through its biogenochemicsal cycle

Mode of nutrition, illustrate the mode of nutrition in parrot

illustrate the mode of nutrition in parrot

What is the use of uncoated polyvinyl chloride, Q. What is the use of Uncoa...

Q. What is the use of Uncoated polyvinyl chloride? Uncoated polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC): PVC and PVDC are closely related plastics that are a

Explain the types of basic forces, Q. Explain the types of basic forces? ...

Q. Explain the types of basic forces? Compression: This refers to the squeezing of the test material so that it still remains as a single undivided unit but may occupy less v

What is risk scoring, What is Risk scoring ? Risk scoring is an instrum...

What is Risk scoring ? Risk scoring is an instrument to assess both the relative risk as well as the absolute risk of developing Cardio-vascular disease and mortality in an ind

Define cooking, Define cooking,blanching and Canning - thermal processing? ...

Define cooking,blanching and Canning - thermal processing? Cooking: Cooking is a primary process to make food more palatable and improve taste. This is not used as a preservati

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