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

Describe the stages of atherosclerosis, Describe the Stages of Atherosclero...

Describe the Stages of Atherosclerosis ? The process of atherosclerosis which gives rise to CAD marches in stages. The earliest recognizable pathologic lesions are the fatty st

Explain about post-operative pain, Post-operative pain  There is some d...

Post-operative pain  There is some discomfort for about 24-48 hours. Persistent pain for a longer duration, with swelling, may indicate possible infection around the implant an

State three main ways in which the body uses food, State three main ways in...

State three main ways in which the body uses food. The body uses food (i) for energy, (ii) for growth (making new cells), (iii) repairing or replacing tissues.

Describe the electron transport system, a) Describe the electron transport ...

a) Describe the electron transport system. Where does it happen in a mitochondrion and what is the role of oxygen in it ? b) Explain the events that happen in the human heart du

Proteins of plant origin - cereal proteins, Proteins of Plant Origin - Cere...

Proteins of Plant Origin - Cereal Proteins Cereal Proteins: Cereal grains, properly ripened and dried for optimum storage stability, have protein content ranging from 6-20%.

Describe the male reproductive system, Describe the Male Reproductive Syste...

Describe the Male Reproductive System? In addition to the primary sex organs, the testes, there are accessory structures that store, nourish, and activate the sperm, and conduc

Examine the cysticerus larva under the microscope, Examine the cysticerus l...

Examine the cysticerus larva under the microscope? Examine the cysticerus larva under the microscope and note the following: i)  Bladder worm consists of a single layered, l

Description and measurement of circadian rhythms, The description and measu...

The description and measurement of circadian rhythms. Describe the standard method used for the recording and graphing of behavioral rhythms in animals, especially the use of

Agro industrial-proteins, Proteins Protease inhibitors: Protease inh...

Proteins Protease inhibitors: Protease inhibitors are protein-based substances widely distributed within the plant kingdom, including the seeds of most cultivated legumes wh

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