2. • In testis, the immature malegerm cell (spermatogonia ) produce
sperms by spermatogenesis
• The spermatogonia ( sing. Spermatogonium ) presenton the inside
of seminiferous tubules multiply by mitotic division and increase in
numbers
• Each spermatogonium isdiploid and contains 46 chromosomes
• Someof thespermatogonia called primaryspermatocytes
periodicallyundergo meiosis
3.
4. • A primary spermatocyte completes the first meiotic division
(reduction division) leading to formation of twoequal, haploid cells
called secondaryspermatocyte, which haveonly 23 chromosomes
• The secondary spermatocyte undergo the second meioticdivision to
produce fourequal, haploid spermatids
5.
6. • The spermatidsare transferred into spermatozoa (sperms) by the
process called spermatogenesis
• After spermatogenesis, sperm heads become embedded in the
sertoli cells, and finally released from the seminiferous tubules by
the process called spermiation
7.
8. • Spermatogenesis starts at the age of puberty due to
significant increase in the secretion of gonadotropin
releasing hormone (GnRH )
• The increased level of GnRH then acts at the anterior
pituitary gland and stimulates secretion of two
gonadotropin – luteinizing hormone (LH) and follicle
stimulating hormone (FSH)
• LH acts at the Leydig cells and stimulates synthesis of
androgens
9. • Androgens stimulate the process of spermatogenesis
• FSH acts on the sertoli cells and stimulates secretion of
some factors which help in the process of spermatogenesis
10.
11. Structure of a sperm
• It isa microscopic structurecomposed of a head, neck, a middle
pieceand a tail
• A plasma membraneenvelops thewhole body of the sperm
• The sperm head contains an elongated haploid nucleus, theanterior
portion of which iscovered by acap-like structure, acrosome
• Theacrosome is filled with enzymes that help fertilizationof the
ovum
• The middle piece possesses numerous mitochondria, which produce
energy for the movementof tail that facilitatesperm motility
