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

What are the types of reproduction that occur in fungi, What are the types ...

What are the types of reproduction that occur in fungi? In fungi there are asexual and sexual reproduction. Fungi replicate asexually by fragmentation, gemmation and sporulatio

What do you mean by bleeding index, Q. What do you mean by Bleeding Index? ...

Q. What do you mean by Bleeding Index? This factor is applicable at this stage to evaluate the health of one stage implants in which the transmucosal component allows the forma

What is pulmonary veins in normal pulmonary vasculature, Q. What is Pulmona...

Q. What is Pulmonary Veins in Normal Pulmonary Vasculature? The right and left upper lobe or superior pulmonary veins descend lateral to the arteries, cross in front of the hil

Etiology and clinical features - neurological disorder, Define Etiology and...

Define Etiology and Clinical Features that causes neurological disorder? The cause of this neurological disorder can be mechanical or paralytic. The mechanical cause is primari

Define about the extra-ocular muscles, Describe about the extra-ocular musc...

Describe about the extra-ocular muscles The extra-ocular muscles are mainly involved in the maintenance of postural tonicity and performance of quick contractions. The prima

Types of aortic stenosis-aortic stenosis-valve disease, Types of Aortic Ste...

Types of Aortic Stenosis:  Obstruction to left ventricular outflow is commonly at the valvar level. Less commonly it is at the sub valvar or supra valvar level. Sub valvar ob

Define dissection of the aorta, Q. Define Dissection of the Aorta ? The...

Q. Define Dissection of the Aorta ? The CXR may be abnormal in upto 80 per cent of patients. The abnormalities include: i) Widened mediastinum: This is defined as a mediast

Biosphere, Biosphere Biosphere is that part of the earth where life can...

Biosphere Biosphere is that part of the earth where life can exist. It is a narfqy layer around the surface of the earth. If you visualise the earth to be the size of an apple

Apsirin determination, Indirect determination: By determining the weight...

Indirect determination: By determining the weight of the filler on the dried filter paper you can calculate the weight of aspirin in each tablet: weight of acetylsalicylic ac

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