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

Enumerate the absolute and relative contraindications, Enumerate the absolu...

Enumerate the absolute and relative contraindications. 1. Absolute contraindications - Recent myocardial infarction - Valvular prosthesis - Severe renal disea

Of which type of tissue are cartilages and bones made, Of which type of tis...

Of which type of tissue are cartilages and bones made? Are the cells of the connective tissue far or near to the others? The relative great spacing among cells is a typical

Explain microorganisms associated with the raw foods, Explain Microorganism...

Explain Microorganisms Associated With The Raw Foods? Foods of animal and plant origin are in direct contact with air, soil and water and get contaminated with the microorganis

Briefly explain about semantides, Q. Briefly explain about semantides? ...

Q. Briefly explain about semantides? The information carrying molecules in plants are called semantides, and they have been recognised to be 3 kinds; deoxyribonucleic acid or D

Describe the part of the female reproductive system, Q. What is the part of...

Q. What is the part of the female reproductive system where fecundation occurs? Fecundation in general occurs in the Fallopian tubes but it can also take place within the uteru

Define the clotting factors, Q. What are clotting factors? Clotting fac...

Q. What are clotting factors? Clotting factors are substances (coenzymes, enzymes, reagents) necessary for the clotting stages to happen. Besides those triggering reagents and

Describe the complex spatial patterns of biodiversity, Q. Describe the comp...

Q. Describe the complex spatial patterns of biodiversity? To describe the complex spatial patterns of biodiversity, ecologists and biogeographers have found it useful to expres

Define the purposes of counselling, Q. Define the Purposes of Counselling? ...

Q. Define the Purposes of Counselling? 1. Supporting individuals to take charge of their own life by: Providing information; Facilitating emotional adjustments; and

How is fecundation done in insects, Q. How is fecundation done in insects (...

Q. How is fecundation done in insects (internal or external)? Is there copulation between insects? Fecundation in insects is internal, with copulation.

Functional principles of excretory organs, Normal 0 false fal...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

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