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 term - microfilaments and microtubules, Define the term - microf...

Define the term - microfilaments and microtubules The cytoskeleton is, in fact, termed as the "bone and muscle" of the eukaryotic cell, and is composed of a network, consisting

What information from the patients symptoms, A 16 year old boy named Jake w...

A 16 year old boy named Jake was admitted into the emergency room complaining of headache, fever, stiffness of abdominal muscles and difficulty swallowing. The doctor on staff bega

How is the nervous system of nematodes organized, Q. How is the nervous sys...

Q. How is the nervous system of nematodes organized? Where are the neural chords located in their body? Roundworms have a ganglial nervous system with an anterior neural ring r

Clinical evaluation of infants and young children, Clinical Evaluation of I...

Clinical Evaluation of Infants and Young Children Approaches to clinical practice advanced in recent year are mostly directed at older children and adolescents. There has not b

Metalimnion - summer stratification, Metalimnion - Summer Stratification ...

Metalimnion - Summer Stratification This zone lies below the epilimnion and above the hypolimnion and thus forms the intermediate layer which is non-circulating. The metalimni

Explain exotic species, Explain exotic species? Describe with the help ...

Explain exotic species? Describe with the help of two examples how the exotic species disturb the native species of an ecosystem ?

Biological challenges, Biology is becoming a more quantitative science, a t...

Biology is becoming a more quantitative science, a trend that has motivated and been recently spurred by advances in computing power and data-gathering technologies. Nowhere is th

Define class – arachnida, Define Class – Arachnida? The class Arachnida (...

Define Class – Arachnida? The class Arachnida (Arachnida = spider) has terrestrial and few aquatic animals. It includes spider, scorpions and mites. 1. Prosoma bears. six pair

What is metachronal wave. describe., What is Metachronal wave? Describe. ...

What is Metachronal wave? Describe. During the coordination of the ciliary movement, bands, or groups of cilia, are at different stages of their beating pattern, and this creat

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