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

Need for insulin in management of type 1 diabetes mellitus, Q. Need for ins...

Q. Need for insulin in management of Type 1 Diabetes Mellitus? Type 1 Diabetes Mellitus occurs when the body's immune system destroys beta cells. Beta cells produce insulin, a

Ornithophily - cross-pollination, Ornithophily - Cross-pollination In ...

Ornithophily - Cross-pollination In tropical areas, the birds dominate over insects as important pollinators. The most common among them are humming-birds, sun-birds and honey

What do you mean by insect control, Q. What do you mean by Insect control? ...

Q. What do you mean by Insect control? The insects can breed and hide in garbage and other places where there is availability of waste materials. The cockroach lives and breed

What is meiosis, What is Meiosis ? Meiosis starts with a diploid cell a...

What is Meiosis ? Meiosis starts with a diploid cell and forms four haploid, or 1n, (or "n") germ cells. These n germ cells fuse during fertilization with another germ cell to

Getting ready to grow bacteria, Getting ready to grow bacteria Secure t...

Getting ready to grow bacteria Secure two or three dozen shallow glass dishes. The glass coasters used to stay bed castors from marring floors will do. Cut 5 cm squares of wind

What is the plasma membrane of the cell, What is the plasma membrane of the...

What is the plasma membrane of the cell? What are its main functions? The plasma membrane is the outer membrane of the cell; it delimits the cell itself and a cell interior wit

Classification, describe in details charateristics of two sub phyla of phyl...

describe in details charateristics of two sub phyla of phylum anthropoda

Genetic recombination, Mutations are the only kind of variability generatin...

Mutations are the only kind of variability generating mechanism in prokaryotes and asexually reproducing organisms. But in eukaryotes where sexual recombination occurs, even in one

Amoeba, AMOEBA Systematic  Position Amoeba  was discovered by  Rus...

AMOEBA Systematic  Position Amoeba  was discovered by  Russel von Rosenhoff in  1755. He  called it the little proteus  after the mythical  sea god who is believed to be c

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

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