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 some examples of phenotypical, What are some examples of phenotypi...

What are some examples of phenotypical characteristics that present two or more varieties and of phenotypical features that do not vary? In relation to the genes correspondent to t

Define the need for classification of plants and animals, Define the Need f...

Define the Need for classification of Plants and Animals? First of all there is a need to know what classification is? Let us define in simple term. Classification is placing o

Ecology, Ecology Very often a word has a precise well-defined meaning i...

Ecology Very often a word has a precise well-defined meaning in scientific literature but is loosely used in everyday language. It is, therefore, necessary for you to be clear

Personnel - neonatal care unit, PERSONNEL It is important that while a...

PERSONNEL It is important that while allocating nursing, medical and paramedical staffs, the needs of the neonatal unit should not be ignored. The highest priority in the orga

Explain positive staining technique, Explain Positive Staining Technique? ...

Explain Positive Staining Technique? Here, a stain has a positively charged chromophore that gets attached to the negatively charged outer surface of the microbial cell and thu

Biology, What are the differences b/w bone and cartiledge

What are the differences b/w bone and cartiledge

Where smooth muscle may be found in human body, a) Name three parts of the ...

a) Name three parts of the body where smooth (involuntary or unstriated) muscle may be found. b) In any one of your examples, say what the smooth muscle does.

Prior to the solving of the structure of dna, Prior to the solving of the s...

Prior to the solving of the structure of DNA, Erwin Chargaff calculated the amounts of the four nucleotides (A, T,G,C) and made which of the following conclusions? A. All four

Categories of benthic flowering plants, Categories of benthic flowering pla...

Categories of benthic flowering plants Zone of emergent plants Consisting of plants whose roots and stems remain submerged in water and whose upper leaves and ste

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