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

Explain difference between monosaccharides and disaccharides, What is the d...

What is the difference between monosaccharides and disaccharides? What are some examples of disaccharides and of monosaccharides that form them? Monosaccharides are simple mole

How is the skin involved in the regulation of temperature, Q. How is the sk...

Q. How is the skin involved in the regulation of body temperature? Skin is one of various organ systems participating in maintaining a core temperature, meaning the temperature

Determine the syndrome of listeriosis, Determine the Syndrome of Listerios...

Determine the Syndrome of Listeriosis Syndrome: Listeriosis in humans is not characterized by a unique set of symptoms since the course of the disease depends upon the state

Determine the model analysis of interocclusal, Model Analysis The study...

Model Analysis The study casts of the patient provide a wealth of information and insight into the treatment decisions and planning. For partially edentulous patients it is cri

Define trace elements for school children and adolescents, Define Trace ele...

Define Trace elements for school children and adolescents? Iodine requirements peak in adolescence. Consumption of iodized salt should be ensured. Adequacy of zinc for growth i

Optic vesicle, Optic vesicle We have explained earlier that the presum...

Optic vesicle We have explained earlier that the presumptive material for the optic vesicles lies in qe eye field in the anterior region of the early neural plate. Experiments

What is the mechanism of elisa, ELIZA stands for enzyme linked immune diffu...

ELIZA stands for enzyme linked immune diffusion assays. It works on standard of antigen antibody reaction.

Pumps, The pumps The blood from the operating field is sucked with t...

The pumps The blood from the operating field is sucked with the help of the cardiotomy sucker and pump, which is filtered to remove all particulate matter and then pass

Three main types of trophic pyramids studied in ecology, What are the three...

What are the three main types of trophic pyramids studied in Ecology? The three kinds of trophic pyramids studied in Ecology are the numeric pyramid, the biomass pyramid and th

Importance of forests - habitat and food, Importance of Forests - Habitat a...

Importance of Forests - Habitat and Food Forests provide habitat, and food as well as protection to wildlife species against extremes of climate and help in balancing carbon d

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