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 about aliphatic alcohols - non glyceride fractions, Define about Ali...

Define about Aliphatic alcohols - Non Glyceride Fractions? These are water-insoluble, with their content varying from 0.5-7% of the unsaponifiable matter. Rice bran oil contain

Reduction in the birth rate, State three conditions in a society which coul...

State three conditions in a society which could contribute to a reduction in the birth rate. Birth rate might be decreased by (i) later marriages (as smaller families), (

Are there non-parasitic viruses, Q Are there non-parasitic viruses? All...

Q Are there non-parasitic viruses? All viruses are necessitating intracellular parasites that are they depend on the host cell to complete their life cycle. A virus does not ha

Different areas of brain, Different areas of brain - HUMA N...

Different areas of brain - HUMA N BRAIN DIFFEREN T AREAS OF BRAIN Note : - In brain glutemic acid metabolins is common In latemaria brain's size

Flowering and endogenous rhythms, Flowering and Endogenous Rhythms Th...

Flowering and Endogenous Rhythms The last four decades of studies in animals and plant physiology have clearly established the existence of a biological clock mechanism to me

Methods to overcome incompatibility, Methods to Overcome Incompatibility ...

Methods to Overcome Incompatibility It has been possible to facilitate the germination of incompatible pollen by extracting pollen wall proteins from compatible pollen and su

Ecological evidence of organisms to environment, Q. Ecological Evidence of ...

Q. Ecological Evidence of organisms to environment? Ecology is concerned with organisms in relationships to their environment. These relationships may be classified as biotic,

Can you explain diabetes mellitus, Q. What is diabetes mellitus? Diabet...

Q. What is diabetes mellitus? Diabetes mellitus is the disease caused by action or deficient production of insulin and the consequent high blood glucose level and low glucose u

Permanent partial disability - injury from an accident, Permanent Partial D...

Permanent Partial Disability - Injury from an Accident Permanent partial disability restrains the worker by doing the job he has been doing. He recovers from the injury in th

How are genetic diseases classified, How are genetic diseases classified? ...

How are genetic diseases classified? The Genetic diseases classify into chromosomal abnormalities and genetic mutations. Between chromosomal abnormalities there are the aneu

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