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

How to reduce calorie intake from fat, How to reduce calorie intake from fa...

How to reduce calorie intake from fat? Efforts should be made to increase the nutrition knowledge of the general public through mass media. The foods with lower fat co

Effects on health - consequences of air pollution, Effects on Health - Cons...

Effects on Health - Consequences of Air Pollution Since the air pollutants are inhaled they attack various parts of the respiratory system on their route to air sacs. Once the

Multipotent scs-pulp tissue revascularization, Multipotent SCs: are cells ...

Multipotent SCs: are cells differentiated & form a number of other tissues, while their sources are not fetal tissue; umblical cord blood & postnatal stem cells including dental p

Comparing the dna of a calfs liver and thymus, When comparing the DNA of a ...

When comparing the DNA of a calfs liver and thymus, which would be predicted to have more DNA and why? What are the differences of the DNA between the two?

Define food business and food technology, Define Food Business and Food Tec...

Define Food Business and Food Technology? The food business and food technology are practically inseparable. The food business may be characterized as: vulnerable to spoilage,

Reduction in left ventricular, Q. Reduction in left ventricular? Vasodi...

Q. Reduction in left ventricular? Vasodilators improve stroke volume, and reduce degree of regurgitation. This results from decrease in systemic vascular resistance and leads t

Periodic variations in light-diurnal and seasonal, Periodic Variations in L...

Periodic Variations in Light-Diurnal and Seasonal We know that rotation of the earth on its axis accounts for day-to-night variations in the amount of radiations falling at a g

Explain sinus venosus defect with partial anomalous venous, Explain Sinus V...

Explain Sinus Venosus Defect with Partial Anomalous Venous Connection ? In this defect the atrial septal defect is situated just below the orifice of superior vena cava above

Thalassemia, Thalassemia   Thalassemias are the commonest hemolytic ana...

Thalassemia   Thalassemias are the commonest hemolytic anaemias or disorder seen in children in India. This is characterised by deficiency  in the synthesis  of one of the norm

Deficiency diseases-phosphorus deficiency, Phosphorus deficiency Defici...

Phosphorus deficiency Deficiency of phosphorus is usually primary and is widespread under natural conditions. It is characterized by pica, poor growth, infertility, and osteody

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