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 principle for estimation of cholesterol - lipids, Define Principle f...

Define Principle for Estimation of cholesterol - Lipids? Zlatkis and associates have evolved a method of quantitative determination of cholesterol based on a reagent containing

How is excretion done in fishes, How is excretion done in fishes? Fish...

How is excretion done in fishes? Fishes have a pair of kidneys that filtrate the blood. Bony fishes excrete nitrogen as ammonia, NH 3 , (they are ammoniotelic) and cartilagino

What do you understand by mesocoel, What do you understand by Mesocoel? ...

What do you understand by Mesocoel? The middle of three coelomic spaces found in tripartate body plan characteristic of deuterostome lineage of animals. Other coelomic compartm

Explain acidic stains (anionic) - types of stains, Explain Acidic Stains (a...

Explain Acidic Stains (anionic) - Types of Stains? These are sodium, potassium, calcium or ammonium salts of coloured acids, which on ionization give negatively charged chromog

Explain the relaxing incision - endodontic surgery, Explain the Relaxing In...

Explain the Relaxing Incision - Endodontic Surgery A short vertical incision placed in the marginal and attached gingival, and located at the extent of the Horizontal incision

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

Temporary Partial Disability - Injury from an Accident Such types of injuries which are easily recoverable and may not incapacitate the victim to perform duty apart from for

Determine fat-soluble vitamins recommended for infant, Determine fat-solubl...

Determine fat-soluble vitamins Recommended for Infant? ICMR (1990) does not give recommendations for vitamins D, E and K. As you already know, vitamin D is expected to be met

Types of parthenocarpy, Types of Parthenocarpy Three types of Partheno...

Types of Parthenocarpy Three types of Parthenocarpy are generally recognized: Genetical Environmental, Chemically-induced. Genetical Parthe

Agro industrial-calcium, Calcium   The calcium content in forages is affe...

Calcium   The calcium content in forages is affected by species, plant part (leaf versus stem), plant maturity, soil content of calcium and climate. Forages are usually a good so

Determine the alpha-islet cells of the pancreas, Determine the alpha-islet ...

Determine the alpha-islet cells of the pancreas. Person X is a healthy human who has volunteered to take experimental drug Y.  Person X has a normal dinner at 6 PM on April 1 a

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