Sperm: Structure ||Class 12 Biology

By -
     A mature spermatozoa or a sperm cell is a microscopic, tadpole-shaped structure of about 2-5 micrometer in diameter and 50 micrometer long. A plasma membrane encloses the whole body of sperm.
     Sperm consists of head, neck, middle piece and tail.

      1. Head: It is flat, oval and composed of a large haploid nucleus and a small cap-like structure called acrosome. It lies at the tip of the nucleus and is formed from the Golgi complex. It contains hydrolytic enzymes and is used to contact and penetrate the egg (ova) during fertilization.

      2. Neck: Neck is the smallest part, it is short structure that contains two centrioles- one parallel to the base of the nucleus and called proximal centriole and other distal centriole perpendicular to the previous one. The proximal centriole enters into the egg during fertilization and starts the first cleavage division of the egg which has no centriole. The distal centriole gives rise to the axial filament which forms the tail.

      3. Middle piece: It is cylindrical in shape and known as the power house of the sperm as it possesses numerous mitochondria to produce energy for the movement of the tail that facilitates sperm motility, essential for fertilization.

      4. Tail: It is a very long (longest part), slender and tapering structure formed of cytoplasm. A fine thread called the axial filament arises from the posterior centrioles and traverses the middle piece and the tail.

Structure of Sperm



Location: India

Comments

Post a Comment

If you have any doubts,please let me know

Popular posts from this blog

Spermatogenesis : Definition & Process ||Class 12 Biology

By -
Image
    Spermatogenesis is the process of formation of spermatozoa (sperms) in the testes which originate from the primordial germ cells (PCGs).     The process of Spermatogenesis initiates at puberty and continues even in the old age.       The process of Spermatogenesis comprised the following two main stages- 1. Formation of spermatids 2. Spermiogenesis 1. Formation of spermatids : It include the following three phases- i) Multiplication Phase ii) Growth Phase iii) Maturation Phase   i) Multiplication Phase : During this phase, the immature germ cells present in the Seminiferous tubules of the testes known as spermatogonia increases in number by mitotic divisions and so that the newly formed spermatogonium possesses the same number at chromosomes.  ii) Growth Phase : Each spermatogonium is diploid (2n) and contains 46 chromosomes. Some of the spermatogonia called primary spermatocytes.  iii)  Maturation Phase : Primary spermatoc...
Read more

Antibody: Structure ||Class 12 Biology

By -
Image
      Antibodies are immunoglobulin (Ig)  molecules. An Antibody seems like a Y-shaped structure. Antibodies are of mainly 5 types such as, IgA, IgM, IgE, IgG and IgD.       Antibodies are glycoproteins. They are typically made of basic structural units that consists of four polypeptide chains: two identical large heavy (H) chains and two identical small light (L) chains connected by disulphide bonds. Hence, an Antibody is represented as H 2 L 2 . The size of an antibody molecule is about 10nm. Each of the four chains has two regions: the constant region and the variable region.         The antibody recognizes a unique molecule of the pathogen, called an antigen via fragment antigen-binding (Fab) site of variable region. An antigen binding site is also called paratope, is a part of an antibody which recognizes and binds to an antigen. The part of antigen to which the paratope binds is called an epitope. The ability of an antibody to...
Read more