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 cell organelles are well-developed in secretory cell, Q. Which cell o...

Q. Which cell organelles are well-developed in secretory cells? In secretory cells, like the secretory cells of endocrine glands, organelles related to production, "exportation

Explain about the amino acids and proteins, Explain about the Amino Acids a...

Explain about the Amino Acids and Proteins? We shall now study the properties of amino acids which we know are the building blocks of proteins.  In this practical, we shall car

Explain risk factors and their role in cad, Explain risk factors and their ...

Explain risk factors and their role in cad ? The concept of risk factors constitutes a major advance for developing strategies to prevent CVD. The Framingham Heat Study played

Competition - processes in succession , Competition - Processes in Successi...

Competition - Processes in Succession The aggregation of individuals in an area leads to inter specific and intra specific competition. The competition is usually for

Explain about the niacin - water soluble vitamin, Explain about the Niacin ...

Explain about the Niacin - Water Soluble Vitamin? Niacin is chemically synonymous with nicotinic acid although the term is also used for its amide (nicotinamide). Nicotinamide

Why is cannibalism an inharmonious ecological interaction, Q. Why is cannib...

Q. Why is cannibalism an inharmonious intraspecific ecological interaction? In the cannibalism an individual eats other of the same species (occurs in some arachnids and insect

How is gas exchange done in flatworms, How is gas exchange done in flatworm...

How is gas exchange done in flatworms? Platyhelminthes exchange gases exclusively by diffusion by their body surface. This is only possible because all cells are localized rela

Planning and implementing nursing care-nephrotic syndrome, Planning of Nurs...

Planning of Nursing Care   Promote nonnal urinary pattern or releive  excess  fluid  Administer medication  as prescribed  Protect the children from secondary  infecti

Water absorption and transpiration, Water Absorption and Transpiration ...

Water Absorption and Transpiration The rate of water absorption is controlled by the rate of transpiration. A high water potential in the atmosphere would reduce water loss fr

Extremes of heat and cold, Extremes of Heat and Cold Deserts are region...

Extremes of Heat and Cold Deserts are regions of aridity with rainfall of less than 20 cm per year and the soil, though L, fertile, is too porous to retain any water. In summer

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