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

How many computers can access the ebook on, I usually study in the library ...

I usually study in the library on the schools computers so I will be accessing the eBook from many different computers throughout the semester. Is there a limit to how many compute

Systematics, classification of all organisms under d phylum protozo

classification of all organisms under d phylum protozoa

Explain the appearance of a single e. coli colony, Describe the appearance ...

Describe the appearance of a single E. coli colony. Why can it be considered genetically homogenous?

Explain the types of cell reproduction, Explain the Types of cell Reproduct...

Explain the Types of cell Reproduction ? One of the major characteristics of living organisms is their ability to grow and reproduce. This is accomplished by cell division. In

Zoogly, are protozoans primitive to life .

are protozoans primitive to life .

Differentiate between osseointegration and osseointegration, Q. List the pa...

Q. List the parameters used to differentiate between osseointegration and fibro osseointegration. The parameters used are: a) Pain b) Rigid fixation - mobility scale, pe

Explain cori cycle , Under the limiting oxygen conditions experienced in ...

Under the limiting oxygen conditions experienced in by vigorous exercise, the configuration of NADH by glycolysis exceeds the ability of the respiratory chain to oxidize it back to

Explain difference between monosaccharides and disaccharides, What is the d...

What is the difference between monosaccharides and disaccharides? What are some examples of disaccharides and of monosaccharides that form them? Monosaccharides are simple mole

Absorbing surface of the small intestine is increased, State three ways in ...

State three ways in which the absorbing surface of the small intestine is increased.   The absorbing surface of the small intestine is increased by:- (a) being very long

Define specialized nutritional formulations for chd, Define Specialized Nut...

Define Specialized Nutritional Formulations for CHD? Achieving calorie and protein requirements with restricted fluid intake, you would realize, is a formidable challenge. Hig

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