organelles of sperm

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These slides concentrate mostly on cellular organelles existing in human sperm cell.

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  • 1. Organelles of Sperm BY SHAHROKH PAKTINAT

2. Introduction Differentiation of germ cells Oocyte Spermatozoon 3. Structure of Mammalian Spermatozoon Sperm head & Sperm tail or flagellum Rodent hook-shaped or falciform Ungulate, carnivore & primate spatula-shaped or spatulate Major distinction: centrosomes 4. Sperm Head Nucleus (DNA & Protamines) Reduced nuclear envelope (removed NPC) Perinuclear theca or perinuclear matrix: Subacrosomal layer Equatorial segment (folded-over complex of PT, IAM & OAM) Postacrosomal sheath (harbor SOAF) 5. Sperm Head 6. Sperm Flagellum 9+2 arrangement of microtubules 9 Outer dense fibers 4 major Segments (innermost and external structures): Connecting piece: 9 segmented columns, capitulum, basal plate Midpiece: mitochondrial sheath, mtDNA Principal piece: annulus, fibrous sheath End piece: axonemal doublets, outer dense fibers 7. Spermiogenesis Extensive remodeling process Biogenesis of accessory structures: Acrosome Amalgamation of cytosol PT Axoneme Head shaping and hypercondensation Centrosome reduction Mitochondria rejection NE reduction 8. Spermiogenesis Recycle of organelles and proteins Ubiquitin-dependent proteolysis (26 S proteasome) E1, E2, E3 & E4 Monoubiquitin regeneration Known substrates: H2A & H3 Mitochondrial membrane protein prohibitin Nucleolar ribonucleoproteins, NPC proteins, nucleoporins 9. Spermiogenesis Transient structures & molecules: Transitional proteins (TP1 & TP2) Pro-acrosomal granules Caudal manchette Chromatid body Residual body & Cytoplasmic droplet (CD) 10. Sperm Transport Liquefaction Chemotaxis (guanylate cyclase, ANP, P91& formylated N-peptides) granulosa cell Capacitation (2-4h in vitro): hyperactivation & acrosome reaction Cholesterol removal Expression of mannose binding site & progesterone receptor Phosphorylation of tyrosine residues Calcium influx ROS 11. Changes of Sperm Head During Fertilization ZP glycoproteins ZP1, ZP2 & ZP3 ZP3 before AR ZP2 after AR Acrosome reaction (proacrosin) P hormone & P-binding protein Receptors of P: PR1 (Ca), PR2 (PTk) & PR3 (Cl & GABA) infertility Zona penetration ubiquitin-proteasome system Equatorial acrosome equatorin 12. Changes of Organelles During Fertilization Surface membranes lost PT dissolved for oocyte activation Smooth NE replaced by maternally derived NE Protamines degraded & replaced by oocyte-derived histones Zygotic centrosome maternal centrosomal proteins + sperm-contributed centriole Mitochondria, axoneme, accessory structures degraded 13. Sperm Incorporation in Ooplasm, Oocyte Activation & Zygotic Development Incorporation of plasma membranes adhesion molecules & receptors In mouse: 61 integrin receptors & ADAM proteins (fertilin & cyritestin) & CD9 Direct contact of equatorial & postacrosomal segments with ooplasm Transmission of SOAF into ooplasm oocyte activation PLC-zeta calcium oscillation-inducing component of SOAF Other PT proteins oocyte activation & early stages of pronuclear development 14. Candidate Molecules Involved in the Sperm- Oocyte Fusion 15. Sperm Incorporation in Ooplasm, Oocyte Activation & Zygotic Development Reversal of histone-protamine exchange Replacement of NPC-free NE by de novo formed NE Sperm contributed mRNAs translated or maternal mRNA silencing Sperm proximal centriole + oocyte pericentriolar material zygotic centrosome Sperm mitochondria degraded by ooplasmic proteasomes Ubiquitin label spermatogenesis Oocyte glutathione Other sperm accessory structures 16. Importance of Centrosome in Fertilization Incomplete centrosomes arrest in fertilization infertility Absence or anomaly Immotile or non-progressive sperms vasectomy anti-centriole antibodies 17. Ultrastructure & Pathology of Human Spermatozoa 18. Thanks for Your Attention

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