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

Dimensions of the cells, On a given microscope, the numerical aperture of t...

On a given microscope, the numerical aperture of the objective is 1.5. The microscope is provided with a filter that selects a wavelength of 500 nm. What is the limit of resolution

Principles of doppler echocardiography, Doppler echocardiogaphy is based on...

Doppler echocardiogaphy is based on  the Doppler effect, which was  described by  the Austrian phy$icist Christian Doppler in  1842. The Doppler effect states that sound frequency

How do embryos of placental mammals excrete nitrogen wastes, Q. How do embr...

Q. How do embryos of placental mammals excrete nitrogen wastes? Placental animals including embryos and excrete urea, In the adult placental mammal urea is excreted through the

What is benedict's test and its principle, What is Benedict's Test and its ...

What is Benedict's Test and its Principle? This test is answered by all reducing sugars with a free aldehyde or ketone groups. Monosaccharides possess a free aldehyde or ketone

Difference between genomes in simple eukaryote, What are the differences be...

What are the differences between genomes in simple eukaryotes vs complex eukaryotes?

Procedure for use microbiological laboratory equipment, Define Procedure fo...

Define Procedure for use Microbiological Laboratory Equipments? Now carry out this activity following the steps given herewith: 1. Observe each instrument (as mentioned abov

Explain about the food science and technology, Explain about the Food Scien...

Explain about the Food Science and Technology? Food Science and Technology are so inextricably linked that usually these are treated as one field of study. While Food Science d

Predict the outcome of future testing, A hypothesis can be used to predict ...

A hypothesis can be used to predict the outcome of future testing. Which type of hypothesis is easier to test? A. It is easier to specify and test for a difference between two outc

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