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

Difference between dominant epistasis and recessive epistasi, What is epist...

What is epistasis? What is the difference between dominant epistasis and recessive epistasis? The Epistasis is the gene interaction in which a gene (the epistatic gene) able to

Temperature - estuaries, Temperature - Estuaries Another importan...

Temperature - Estuaries Another important variable is temperature. The temperature of estuary keeps on fluctuating it heats up and cools down more rapidly under prevailin

Explain plain dwellers, Which two of the following changes (a - d) usually ...

Which two of the following changes (a - d) usually tend to occur in the plain dwellers when they move to high altitudes (3,500 m or more)? 1. Enhance in red blood cell size 2

Observing root hairs, Observing root hairs Study the root hairs with a ...

Observing root hairs Study the root hairs with a hand lens and view how they are constructed.

Classification, What is omnispective classification

What is omnispective classification

Genetics , write about complementary genes

write about complementary genes

Gastropods - feeding and digestion in molluscs, Gastropods - Feeding and Di...

Gastropods - Feeding and Digestion in Molluscs In several gastropods the digestion is extracellular. Though, some herbivore gastropods like Crepidula are ciliary feeders and h

Solubility of gases in water, Solubility of Gases in water Most gases w...

Solubility of Gases in water Most gases which are important for biological processes dissolve readily and specially in water. The solubility of any gas in water generally var

Serotonin - enhancement of memory, Q. Serotonin - Enhancement of memory? ...

Q. Serotonin - Enhancement of memory? Increased level of serotonin is implicated in the enhancement of memory. It plays a significant role in classical conditioning wherein sti

What are halophile, What are halophile, thermoacidophile and methanogen arc...

What are halophile, thermoacidophile and methanogen archaebacteria? There are three peculiar parts of archaebacteria. The halophile archaebacteria only survive in salt-rich env

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