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Formation of Gametes [PDF] Formation of gametes Dr. Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Formation of gametes • Types of gametes – Male gamete = Sperm -Female gamete = Ovum • Process of formation Sperms = Spermatogenesis Ovum = Oogenesis Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Spermatogenesis • Site of spermatogenesis- testis • Process (Spermatogenesis) • -Spermatocytosis • -Spermatidogenesis • -Spermeiogesis • Maturation • Structure of Sperm Dr Navneet Kumar Professor Anatomy KGMU Lko Spermatogenesis Site of spermatogenesis - testis • Structure of testis • coverings • -Tunica vaginalis • -Tunica albugenia • -Tunica vasculosa • Cells • Spermatogenic cells • Supporting cells • Interstitial cells • Dr Navneet Kumar Professor Anatomy KGMU Lko Dr. Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Supportive cells -Sertoli cells -Provide nutrition Interstitial cells Leyding cells -Secret male hormone at puberty Dr Navneet Kumar Professor Anatomy KGMU Lko Spermatogenesis- process 1.Spermatocytosis • -Primodial or gem cells • -Spermatogonia –type A • -type B • -Primary spermatocyte • -Secondary spermatocyte 2.Spermatidogenesis • -Spermatids 3.Spermeiogenesis Dr Navneet Kumar Professor Anatomy KGMU Lko 1.Spermatocytosis Spermatocytosis- - Initiate at puberty - the primitive germ cells of seminiferous tubules grow and get enlarged then divide in different forms of cells (a)Spermatogonia(44,XY) The primary germ cells undergo division and produce a number of cells termed spermatogonia, Dark- type A cells light -type A cell and type B cells Type B spermatogonia cells- grow as primary spermatocyte . Dr Navneet Kumar Professor Anatomy KGMU Lko 1.Spermatocytosis……. (b) Primary spermatocyte (44,XY) • Type B Spermatogonium cells grow further and from primary spermatocyte. • The primary spermatocyte enter in 1st phase of meiotic division i.e reduction division (c) Secondary spermatocyte (22,X&22,Y) -One primary spermatocyte divide in two Secondary spermatocytes -The secondary spermatocytes have half number of chromosomes from parent cell • One secondary spermatocyte has 22X and another has 22Y Dr Navneet Kumar Professor Anatomy KGMU Lko 2.Spermatidogenesis • Spermatidogenesis- is formation of spermatids • Spermatids(22X or 22Y) • Both secondary spermatocyte enter in 2nd phase of meiotic division. • Each secondary spermatocyte divide in two daughter cells • The four daughter cells are spermatids Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Spermeiogenesis • Spermeiogenesis- • Head = chromatin • Acrosome = Golgi apparatus • Mid piece = mitochondria • Centrioles = tail of the sperm. • spermiation Dr Navneet Kumar Professor Anatomy KGMU Lko Spermeiogenesis Dr Navneet Kumar Professor Anatomy KGMU Lko • Spermiation • Maturation of sperm • Capacitation • -acrosome reaction • -zona reaction Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Sperm or spermatozoon Head - is oval or elliptical, -The head contains a mass of chromatin, and is generally regarded as the nucleus of the cell surrounded by a thin envelope. -Apex has acrosomal cap Neck - constricted area below head in the human spermatozoön. -The anterior centriole, represented by two or three rounded particles, is situated at the junction of the head and neck, and behind it is a band of homogeneous substance. Dr Navneet Kumar Professor Anatomy KGMU Lko Spermatozoon…… Structure Connecting piece or body or middle piece is rod-like, and is limited behind by a terminal disk. -The posterior centriole is placed at the junction of the body and neck and, like the anterior, consists of two or three rounded particles. Axial filament • From this centriole an axial filament, surrounded by a sheath, runs backward through the body and tail. • mitochondria sheath. In the body the sheath of the axial filament is encircled by a spiral thread, around which is an envelope containing mitochondria granules, and termed the mitochondria sheath. Dr Navneet Kumar Professor Anatomy KGMU Lko Spermatozoon…… Structure • Tail or Principal piece is of great length, and consists of the axial thread or filament, surrounded by its sheath, which may contain a spiral thread or may present a striated appearance. The terminal portion or end-piece of the tail consists of the axial filament only Dr Navneet Kumar Professor Anatomy KGMU Lko Dr Navneet Kumar Professor Anatomy KGMU Lko Thanks Dr Navneet Kumar Professor Anatomy KGMU Lko M.C.Q 1 • Which one is haploid (a) Secondary spermatocyte (b) Spermatogoneum (c) Primary spermatocyte (d) Primitive germ cell Dr Navneet Kumar Professor Anatomy KGMU Lko M.C.Q 2 • Sperm are modified form of (a) Secondary spermatocyte (b) Spermatogoneum (c) Primary spermatocyte (d) Spermatids Dr Navneet Kumar Professor Anatomy KGMU Lko M.C.Q 3 • Spermiation is (a) Formation of spematids (b) Formation of spermatogoneum (c) Removal of dead sperm (d) Removal of excess cytoplasm of sperm Dr Navneet Kumar Professor Anatomy KGMU Lko M.C.Q 4 • End piece of spermatozoa contain (a) Axial filaments (b) Fibrous sheath (c) Terminal disc (d) Acrosomal cap Dr Navneet Kumar Professor Anatomy KGMU Lko M.C.Q 5 From spermatogonium, the sperm is formed in (a) 54 days (b) 64 days (c) 54 hours (d) 64 hours Dr Navneet Kumar Professor Anatomy KGMU Lko .
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