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

Define the indicators of nutrition, Define the Indicators of Nutrition? ...

Define the Indicators of Nutrition? We will begin our study on this topic by first understanding what we mean by an indicator. An indicator is a "specific and measurable statis

Signal transduction, Signal Transduction The body consists of a huge va...

Signal Transduction The body consists of a huge variety of cell types which must work together to sustain the life of an organism. They must respond to their environment and co

Compound leaf, Compound leaf is the leaf in which the blade forms small le...

Compound leaf is the leaf in which the blade forms small leaflets. Compound leaves which have several small leaflets originating from the central axis are termed as pinnately comp

Explain tertiary butylhydroquinone, Tertiary Butylhydroquinone (TBHQ) T...

Tertiary Butylhydroquinone (TBHQ) TBHQ is moderately soluble in oil and slightly soluble in water. In many cases, TBHQ is more effective than any other antioxidant in providing

Events prior to the sperm-egg fusion, Events prior to the Sperm-Egg Fusion ...

Events prior to the Sperm-Egg Fusion In a number of organisms that have been studied, the sperm remain immotile in the testis or in the semen. The sperm become active and mot

Genetic, 1. The genes for ruby eyes (rb), tan body (t) and cut wings (ct) a...

1. The genes for ruby eyes (rb), tan body (t) and cut wings (ct) are all found on the X-chromosome of Drosophila melanogaster. All of these are recessive traits. They map in the or

Botany, what is affinites of gymnosperm

what is affinites of gymnosperm

Excretory system, What is the excretory organ of an agama lizard?

What is the excretory organ of an agama lizard?

How can the formation of egg cells from germ cells, Indicating the name and...

Indicating the name and respective ploidy of each involved cell how can the formation of egg cells from germ cells be described? The formation of egg cells starts with a germ c

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