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 is obesity in biochemical or physiological risk, What is Obesity in bi...

What is Obesity in biochemical or physiological risk ? Obesity results from a complex interaction of genetic predisposition and environmental factors operating throughout an in

How water balance take place in human body, How Water Balance Take Place in...

How Water Balance Take Place in Human Body? The amount of fluid in the body is tightly controlled because imbalance can be devastating. In a normal individual, the maintenance

Explain isolated chloroplast thylakoids, In an experiment, isolated chlorop...

In an experiment, isolated chloroplast thylakoids were incubated at pH 4.0 with ADP and inorganic phosphate (Pi) added to the medium and then transferred to a medium having pH 8.0.

Define national programmes targeting children and adolescent, Define Nation...

Define National Programmes Targeting Children and Adolescents? Two programmes specially target children and adolescents as a vulnerable group. These are: a) Mid Day Meal Pro

Define who classification for assessment of vitamin a status, Define WHO cl...

Define WHO classification for assessment of vitamin A status? In addition, to the above mentioned manifestations, thickening of the hair follicles (follicular hyperkeratosis) i

Name main parts into which a neuron can be divided, What are the three main...

What are the three main parts into which a neuron can be divided? What are their respective functions? The three mains parts into which a neuron can be didactically separated a

Neurological assessment of new born, Neurological Assessment The neuro...

Neurological Assessment The neurological assessment is made up of eight neurological criteria which have high, significance with gestational age. (Fig. 3.2) In order to perf

Development of endosperm, Development of Endosperm In a fertilized emb...

Development of Endosperm In a fertilized embryo sac, the primary endosperm nucleus is generally observed below the zygote. It divides, and further divisions of its products gi

Describe the stages of atherosclerosis, Describe the Stages of Atherosclero...

Describe the Stages of Atherosclerosis ? The process of atherosclerosis which gives rise to CAD marches in stages. The earliest recognizable pathologic lesions are the fatty st

What are changes in st-segment, Q. What are changes in ST-Segment? Nor...

Q. What are changes in ST-Segment? Normal Exercise Electrocardiogram ST and J Point As the heart rate increases with exercise, a number of predictable changes occur in 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