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

What is the major biological function of ribosomes, Q Where in the cell can...

Q Where in the cell can ribosomes be found? What is the major biological function of ribosomes? Ribosomes can be found free in the cytoplasm, adhered to the external side of th

Pollination, Pollination Pollination refers to the transfer of pollen...

Pollination Pollination refers to the transfer of pollen from dehiscing anthers to the pistil. Unlike animals, plants cannot move to their mates for sexual reproduction. Henc

Respiration of seeds, How can i design an experiment to compare the heat ou...

How can i design an experiment to compare the heat output by two different types of germinating seeds?

Define different uses of additives in food, Normal 0 false fa...

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

What is a photosynthesis, Photosynthesis is a process used by plants and ot...

Photosynthesis is a process used by plants and other organisms to change the light energy captured from the sun into chemical energy which can be beneficial to fuel the organism's

Metalimnion - summer stratification, Metalimnion - Summer Stratification ...

Metalimnion - Summer Stratification This zone lies below the epilimnion and above the hypolimnion and thus forms the intermediate layer which is non-circulating. The metalimni

Phylum Coelenterata, What is the adaptative radiatoin of coelenterates

What is the adaptative radiatoin of coelenterates

Minerals requirements for dyslipidemia, Q. Minerals requirements for dyslip...

Q. Minerals requirements for dyslipidemia? Minerals: The three most important minerals are chromium, zinc and magnesium. These minerals play a critical role in maintaining p

What is the single tooth implant case, In Single Tooth Implant Case: a)...

In Single Tooth Implant Case: a) Vertical distance available between the crest of residual ridge to the opposing occlusal surface. At least 7 mm space is required to a cementab

Movement of carbon dioxide into a leaf, a) What process is responsible for ...

a) What process is responsible for the movement of carbon dioxide into a leaf? b) In what conditions might the same process cause oxygen to enter a leaf?   (a) Diffusi

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