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 changes in feeding behaviour of infants, Explain Changes in feeding...

Explain Changes in feeding behaviour of infants? On maturation of neuro-muscular system, the body is able to coordinate sucking, swallowing and breathing. Till about three mont

Descent of the testis, Descent of the Testis The testis develops on ...

Descent of the Testis The testis develops on the posterior abdominal wall at the mesonephric ridge. To reach the adult position in the scrotum, it must decent. A fibrous cor

Define life cycle of spore forming bacteria, Define Life Cycle of Spore For...

Define Life Cycle of Spore Forming Bacteria? One endospore is formed per bacterial cell. The process of formation of endospore is called sporulation that occurs in an organized

Charles darwin was the first person, Charles Darwin was the first person to...

Charles Darwin was the first person to suggest that: a. the present forms of all existing species are the result of natural selection b. species have changed over long periods of t

Developmental biology, a recent topic for my developmental biology assignm...

a recent topic for my developmental biology assignment

Explain about the physiological accommodation, Explain about the Physiologi...

Explain about the Physiological Accommodation Physiological Accommodation contractile power of the ciliary muscle required to change the focussing power of the eye by ID. Meas

How do white cells differ from red cells, How do white cells differ from re...

How do white cells differ from red cells (a) In their structure, (b) Their function?   a) White cells have nuclei, red cells do not have nucle

How the rhizopus reproduce?, How the Rhizopus reproduce? Rhizopus usual...

How the Rhizopus reproduce? Rhizopus usually reproduce asexually, but under unfavourable conditions, sexual reproduction (isogamous) occur resulting in formation of zygospores

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