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

Amphibian circulation be classified as incomplete and double, Q. Why can th...

Q. Why can the amphibian circulation be classified as incomplete and double? The amphibian circulation is double because it is composed of pulmonary and systemic circulations r

Show clinical symptoms of galactosemia, Q. Show Clinical symptoms of galact...

Q. Show Clinical symptoms of galactosemia? Clinical symptoms of galactosemia deficiency is found to appear early in infancy. Some infants are born with cataract, jaundice and

What is pinocytosis, Pinocytosis: - The  ingestion of dissolved materials  ...

Pinocytosis: - The  ingestion of dissolved materials  by  endocytosis.  The cytoplasmic membrane invaginates and pinches off placing small  droplets of fluid  in  a  pinocytic vesi

Include the uncertainty interval and confidence level, What is the minimum ...

What is the minimum sample weight, at USP standards (U = 0.1% and k = 3), that can be measured on an analytic balance in which the repeatability is 0.0001 g. Include the uncertaint

Gene therapy, In experimental studies, gene therapy has been shown to impro...

In experimental studies, gene therapy has been shown to improve failing human myocardial function. The abnormal function of  myocytes obtained from patients with dilated cardiomyop

What is subphylum crustacea and subphylum uniramia, What is Subphylum Crust...

What is Subphylum Crustacea and Subphylum Uniramia? The Arthropoda are usually grouped into four subgroupings called subphyla (singular-subphylum). One of these four subphyla -

Determine the chance of developing cancer, A typical chest x-ray exposes th...

A typical chest x-ray exposes the patient to a radiation dose of 0.01 rem. If a man receives 10 such x-rays in a lifetime, what is his chance of developing cancer as a result of th

Describe anthracycline cardiomyopathy, Q. Describe Anthracycline Cardiomyop...

Q. Describe Anthracycline Cardiomyopathy? It is due to anticancer agent doxorubion (Adriamycine), when the cumulative dose exceeds 450 mg/m 2 in subjects with normal hearts. I

Natural vegetative propagation, in natural vegetative propagation which st...

in natural vegetative propagation which structure gives rise to new individuals?

Define primary and somatic sensory area, Q. Define Primary and Somatic Sens...

Q. Define Primary and Somatic Sensory Area? Primary Sensory Area - Located in postcentral gyrus in parietal lobes (just posterior to central sulcus).  Neurons here receive info

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