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

Imaginal discs, Imaginal Discs In the holometabolous larva, there are ...

Imaginal Discs In the holometabolous larva, there are two cell populations: (1) The larval cells that are used for the larval structures and (2) The imaginal disc and th

Define the fact that we must eat to gain the energy, Which law of thermodyn...

Which law of thermodynamics explains the fact that we must eat to gain the energy to perform the functions of life, such as breathing? a. fourth law b. first law c. second law d

Explain epidemiological studies, Epidemiological studies The use of ava...

Epidemiological studies The use of available data from  the positive epidemiological studies in  the  risk assessment is encouraged. Data derived fiom human clinical studies, s

Netlike membranous complex of superposed flat saccules, Q. A netlike membra...

Q. A netlike membranous complex of superposed flat saccules with vesicles detaching from the extremities seen in electronic microscopy. What is the observed structure? What is its

What is intra oral and extra oral, What is Intra oral and Extra Oral A...

What is Intra oral and Extra Oral A) Intra oral a) Frontal in occlusion b) Left and right occlusion (Using intra oral photography mirror) c) Occlusal view maxillary

Transport of macromolecules, Nuclear transport is an energy-dependent proce...

Nuclear transport is an energy-dependent process mediated through saturable receptors. Export and Import receptors are by to distinguish and bind to nuclear localization signals or

Death of post-thymic lymphocytes induced by corticosteroid, A 21-year-old w...

A 21-year-old woman presents with a 3-month history of malaise, joint pain, weight loss, and sporadic fever. Her temperature is 38°C (101°F). The serum antinuclear antibody (ANA) t

Explain clinical manifestations of cardiomyopathy, Q. Explain Clinical Mani...

Q. Explain Clinical Manifestations of cardiomyopathy? 1) Asymptomatic, when the diagnosis is made by 2D Echocardiography. 2) Enlargement of LV. Apex is shifted down and out.

List in sequential order the organelles, Starting from a ribosome in the cy...

Starting from a ribosome in the cytosol, list in sequential order the organelles and cellular components a secreted protein would encounter from translation to secretion.

Enumerate about the minerals and rocks, Minerals and Rocks      A mine...

Minerals and Rocks      A mineral is an inorganic body, formed by the process of nature, usually having a definite composition. If formed under favourable conditions, it has 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