Process of Acrosomal Reaction.pptx

Acrosomal Reaction

1. PROCESS OF ACROSOME REACTION Prepared By Nirvik Nyaupane VGO -M-04-2021 M.V.Sc (Theriogenology) Agriculture and Forestry University (AFU), Rampur

2. The acrosome is a special kind of organelle with a cap-like structure that covers the anterior portion of the head of the spermatozoon. The acrosome is formed from golgi apparatus during the golgi phase and acrosomal phase of spermatid differentiation containing digestive enzymes which are required for penetration of the zona pellucida of the ovulated oocyte. The acrosome is a membrane bound lysosome that contains hydrolytic enzymes ( acrosin , hyaluronidase , zona lysin , esterases and acid hydro lases) Introduction

3. Factors to be considered Spermatozoa contain specific proteins on their plasma membrane surface that bind specifically to glycoproteins of zona pellucida Zona pellucida contains three glycoproteins ZP1,ZP2 , ZP3 During fertilization the acrosome undergoes an ordered, highly specialized exocytosis, known as the acrosome reaction, that allows release of the enzymes that are packaged in it to digest or penetrate the zona pellucida . Process of Acrosomal Reaction ZP1 & ZP2 provide the structural integrity of the zona ZP3 binds to proteins on the spermatozoal membrane

4. Process of Acrosomal Reaction

5. ZBR ZBR reacts with ZP3 to cause physical attachment of the sperm to the zona pellucida . The sperm plasma membrane overlying the acrosome contains two receptor-like regions; Zona Binding Region ( ZBR ) and Acrosomal Reaction Promoting Region ( ARPR ) Process of Acrosomal Reaction ARPR also binds to ZP3 and initiates the acrosome reaction by causing the sperm plasma membrane to fuse to the outer acrosomal membrane. ARPR

6. Vesiculation (fusion result in formation of many vesicles) The acrosomal reaction is an orderly fusion of the sperm plasma membrane with the outer acrosomal membrane. Process of Acrosomal Reaction Vesiculation creates pores through which the acrosomal enzymes can pass

7. Acrosin : responsible for hydrolyzing zona proteins also enhances the ability of sperm to bind to the zona The release of acrosomal enzymes allows the spermatozoon to digest its way through the zona pellucida Process of Acrosomal Reaction Mechanical force generated form flagellar action of tail maintain sperm head contact with the zona Th e spermatozoon digest a small hole through the zona leaving the other portion of zona predominately intact.

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