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

Atrial arrhythmias-peri operative problems, Atrial Arrhythmias :  Atl...

Atrial Arrhythmias :  Atlial fibrillation is the most common rhythm abnormality after CABG. Paroxysmal atrial tachycardia and atrial flutter are less common. Increased sympat

What is connective tissue proper, What is connective tissue proper? The...

What is connective tissue proper? The name connective tissue proper is used to assign the connective tissue that fills interstitial spaces as opposed to the specialized connect

Agro industrial-factors affecting vitamin utilization, Factors affecting vi...

Factors affecting vitamin utilization Raw soybean contains enzyme lipoxygenase which can be destroyed by heating for 5 min with steam at atmospheric pressure. Lipoxygenase cata

Electrocardiography, E l ec t r o c ar d i og...

E l ec t r o c ar d i og r ap h y : This equipment is used to identify cardiac conduction abnormalities that limit heart perf

Qualitative changes, Qualitative Changes The qualitative changes in th...

Qualitative Changes The qualitative changes in the structure of proteins in response to stress can lead to the following: Resistance against denaturation of prote

Define the factors causing underweight - etiology, Define the Factors Causi...

Define the Factors Causing Underweight - Etiology? There are a number of factors causing underweight. These are: Poor selection of food Physical activity Mothe

Why superoxide radical scavenging of beverages, Why is Superoxide radical s...

Why is Superoxide radical scavenging of beverages such red wine, grape juice measured at 560 nm?

Zoology, Is viruses classified as living organism? If yes/no why

Is viruses classified as living organism? If yes/no why

Onset of puberty in male, ONSE T OF PUBERTY IN MALE Puberty is the ...

ONSE T OF PUBERTY IN MALE Puberty is the period when reproductive organs become functional. It is attained at the age of 13-16 yrs. It is stimulated by testasteron. I

Nutritional management of paediatric and geriatric problems, Define Nutriti...

Define Nutritional Management of Paediatric and Geriatric Problems? This unit focused on the paediatric and geriatric problems and their nutritional management.Initially, the c

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