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

What do you mean by transgenic food, Q. What is transgenic food? The Tr...

Q. What is transgenic food? The Transgenic beings are animals, microorganisms and plants that contain recombinant DNA that is genes from other microorganisms, plants or animals

Multiplication phas - stages of spermatogenesis, Multiplication Phas - Stag...

Multiplication Phas - Stages of spermatogenesis The initial cells in the germ line arc known as primordial germ cells (PCC). The PGC, which arise at some distance from the pro

Cell theory, Normal 0 false false false EN-IN X-NONE ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Whcih group of individual animals and plants called species, Q. Whcih group...

Q. Whcih group of individual animals and plants called Species? A group of individual plants and animals that are fundamentally alike is treated as a ,species. Species is a par

Sticky sweet method-endodontics principles, Sticky sweet method Richwi...

Sticky sweet method Richwil crown and bridge remover -It is a resin block of water-soluble , like a stick sweet -It is first softened in hot water -Placed on the restorat

Assessment of tricuspid and pulmonary orifice areas, Assessment of Tricusp...

Assessment of Tricuspid and Pulmonary Orifice Areas Due to the rarity of tricuspid stenosis and pulmonary stenosis, no general agreement exists on what constitutes critical o

Proteins of animal origin - egg, Proteins of Animal Origin - Egg Eggs: ...

Proteins of Animal Origin - Egg Eggs:  Roughly, the chicken egg consists of 11% shell, 31% yolk and 58% white. Liquid whole egg consists of 65% white and 35% yolk. The primary

Difference between ectoparasite and endoparasite, What is the difference be...

What is the difference between ectoparasite and endoparasite? Ectoparasites are parasites that explore the external surface of the host (as, for example, mites that parasite th

Describe about the implant surgeon, Describe about The implant surgeon ...

Describe about The implant surgeon The implant surgeon should have basic knowledge of the macroscopic and microscopic anatomy of the jaw bones with their associated neurovascul

Explain fosamprenavir calcium, Explain Fosamprenavir calcium It is a pr...

Explain Fosamprenavir calcium It is a prodrug of amprenavir, was recently approved by the FDA for use in HAART. In patients who have not lastly been treated with a protease inh

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