Spermeiogenesis / spermetoleosis, Biology

Assignment Help:

SPERMEIOGENESIS / SPERMETOLEOSIS

It is the gradual differentiation of a stationary rounded and undifferentiated spermatid into an active and motile sperm.

The spermatids formed as a result of maturation divisions are typical undifferentiated animal cells containing mitochondira, golgi body and centriole but with a haploid set of chromosomes.

In spermeiogenesis following changes take place -

(i) Formation of acrosome

  1. The acrosome of spermatozoan is derived from golgi complex of the spermatid.
  2. In a spermatid the golgi compelx is in the form of a spherical body, comprising of numerous vesicles or small vacuoles in the centre surronded by several rows of concentrically arranged cisternae.
  3. As the differentaition proceeds, the arrangement of cisternae becomes irregular and one or two vacuoles enlarge to replace the vesicles.
  4. Inside each large vacuole appears a small dense body, the proacrosomal granule.
  5. The vacuole with its acrosomal granule enlarges in size, migrates towards the anterior pole and gets attached to the tip of elongated nucleus forming a sort of cap.
  6. The proacrosomal granule enlarges further and forms the acrosomal granule.
  7. It forms core of the acrosome. The vacuole loses its liquid content spreads over the acrosomal granule and half of the nucleus forming of spermatozoan.
  8. The remainder of golgi body undergoes a gradual regression and is discardd as golgi rest together with the cytoplasm of spermatid.

357_formation of acrosome.png

Formation of Acrosome

(ii) Formation of Perforatorium

A rounded small pit present below the nucleus, in this part G actin and Ca++  ions are present. This spaces is called perforatorium space.

(iii) Nuclear changes

  1. The nucleus shrinks by losing water from the nuclear sap and the chromosome closely packed.
  2. The step is essential, since it reduces the weight of spermatozoon and enhances its motility.
  3. Even RNA and other accessory materials are also removed leaving only the hereditary material.

(iv) Tail

  1. The axial filament of the tail of spermatozoan is formed the centriole of spermatid.
  2. The distal centriole gives rise to the axial filament of the flagellum and acts as a basal granule.
  3. The proximal centriole enters the ovum along with sperm nucleus and mitotic spindle formation for the first division of the zygote nucleus.

(v) Formation of mitochondrial spiral and middle piece

  1. The proximal part of axial filament and distal centriole in the middle piece of spermatozoan.
  2. Gradually, these mitochondria lose their individuality and partly fuse together forming two densely packed bodies one on either side of axial filament.
  3. The mitochondrial sheath provides energy and strength to the sperm when it swims or moves towards the ovum.
  4. During the process of spermeiogenesis all the mitochondria of the spermatid fuse to form a nebenkern or Jensen's sheath.
  5. The nebenkern provide required energy to the sperm.
  6. The nebenkern along with little cytoplasm form a spiral sheath around the anterior end of the axial filament which is called as manchette.

(vi) Changes in the cytoplasm

  1. During the acrosome formation cytoplasm move to backside and maximum part store in the middle piece of sperm.
  2. Tail formation occurs and mitochondria's are arranged in middle piece and cytoplam arranged as manchette.

(vii) Sperm sheath

Sperm sheath is form of mucopolysaccharide. It is also called glycocalyx. This sheath probably function as antigen.


Related Discussions:- Spermeiogenesis / spermetoleosis

Role of glucose in metabolism, ROL E OF GLUCOSE - Maximum part of ener...

ROL E OF GLUCOSE - Maximum part of energy in percentage is obtained by oxidation of glucose. Energy is released quickly. In blood .1% glucose (C6H12O6) present. Norma

Name the rich source of aerobic bacteria, 1. Biogas is produced by the acti...

1. Biogas is produced by the activity of aerobic bacteria on animal waste 2. Methanobacterium is an aerobic bacterium found in rumen of cattle 3. Biogas, commonly called goba

Nucleic acids, Nucleic Acids Friedrich Miescher  (1868) discovered the ...

Nucleic Acids Friedrich Miescher  (1868) discovered the presence  of these compound  in protoplasm ,but Altman (1889) introduced the term Nucleic acid. These  acids are the lar

Digestive system, identify structural modifiactions of the stomach and smal...

identify structural modifiactions of the stomach and small intestine walls that enhance the digestive processes in these regions

Are mollusc metameric beings, Are mollusc metameric beings? Exclusively ana...

Are mollusc metameric beings? Exclusively analyzing this feature could it be said that molluscs are evolutionarily proximal to nematodes or to annelids? In molluscs there is no

What are the three main parts of a eukaryotic cell, The eukaryotic cell can...

The eukaryotic cell can be separated into two major portions: the cell membrane that divides the intracellular space from the outer space phisically delimiting the cell; the cytopl

What is the energy source used in active transport, What is the energy sour...

What is the energy source used in active transport through biological membranes? The energy essential for active transport (against the concentration gradient of the transporte

Define procedure for gram staining of bacterial cultures, Define Procedure ...

Define Procedure for Gram Staining of Bacterial Cultures? Now carry out the exercise following the steps enumerated herewith: 1. Label the nutrient agar plates with the name

Explain the process of metastasis, Explain the process of metastasis. Defin...

Explain the process of metastasis. Define anti-angiogenic drugs and relate the role of medical imaging, if any, in anti-angiogenic drug therapy. State how you envision your particu

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

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