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

Describe technique operation prosthetic valve endocarditis, Describe the Te...

Describe the Technique of Operation in prosthetic valve endocarditis? The operative principle is drainage of abscess, removal of debris and valve rep or replacement to reverse

Digestive system - salivary glands, SALI V A R Y GLAND - These are ...

SALI V A R Y GLAND - These are compound - Alveolar, tubular glands made up of columnar / cuboidal epithelium. Saliva is manufactured in them. In mammals these are pai

Explain arrayed library, Arrayed library: An individual primary recombinan...

Arrayed library: An individual primary recombinant clones (hosted in the phage, cosmid, YAC, or other vector) which are placed in two- dimensional arrays in microtiter dishes. Eac

What is radiographic assessment, What is Radiographic Assessment Radio...

What is Radiographic Assessment Radiographic Assessment: Radiographic examination is very different with implants than with teeth. Radiographs are frequently used in implant

Explain radiology, Radiology is a medical specialty that employs the use of...

Radiology is a medical specialty that employs the use of imaging to both diagnose and treat disease visualised within the human body. Radiologists use an array of imaging technolog

Illustrate the confer processivity on dna polymerase, Which of the followin...

Which of the following best defines the reasons why the sliding clamp is able to confer processivity on DNA polymerase and not DNA primase? A. The sliding clamp coats the templ

Define protein requirements for physical fitness, Define Protein Requiremen...

Define Protein Requirements for physical fitness? Proteins provide energy to the body. Since exercise may increase an athlete's need for protein, depending on the type and freq

Cell cycle, The cell cycle undergoes a sequence of changes which invol...

The cell cycle undergoes a sequence of changes which involve a period of growth replication of DNA, Followed by cell division. This sequence of changes is called cell cycle.

What do numeric pyramids represent, What do numeric pyramids represent? ...

What do numeric pyramids represent? Numeric pyramids show the number of individuals in each trophic level of a food chain.

Inferior alveolar nerve, Inferior alveolar nerve Inferior alveolar ner...

Inferior alveolar nerve Inferior alveolar nerve repositioning to facilitate the placement of endosseous implants posterior to mental foramen is associated with very high incid

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