Fertilization Process PDF

### Fertilization Process **1. Journey of Sperm and Egg:** - - **2. Sperm-Egg Binding and Penetration:** - - - **3. Activation of the Oocyte and Prevention of Polyspermy:** - - ### 1. Activation of the Oocyte When a sperm successfully penetrates the oocyte's outer membrane (...

### Fertilization Process **1. Journey of Sperm and Egg:** - - **2. Sperm-Egg Binding and Penetration:** - - - **3. Activation of the Oocyte and Prevention of Polyspermy:** - - ### 1. Activation of the Oocyte When a sperm successfully penetrates the oocyte's outer membrane (oolemma), a series of biochemical and structural changes are triggered, leading to the oocyte\'s activation. These changes allow the oocyte to complete its maturation and prepare for the next stages of development. - - - - ### 2. Prevention of Polyspermy **Polyspermy** occurs when more than one sperm fertilizes an egg, leading to an abnormal number of chromosomes (polyploidy) in the zygote. This condition is incompatible with normal development, so mechanisms to prevent additional sperm from fertilizing the egg are crucial. Two primary mechanisms in the oocyte prevent polyspermy: #### A. Fast Block to Polyspermy (Membrane Depolarization) - - #### B. Slow Block to Polyspermy (Cortical Reaction) The slow block is a longer-lasting response that reinforces the prevention of polyspermy. - - - **4. Formation of the Zygote:** - ### Cleavage: Rapid Cell Divisions After fertilization, the zygote undergoes cleavage, a series of rapid mitotic divisions without growth, leading to the formation of a multicellular structure. **1. Initial Stages of Cleavage:** - - - **2. Morula Stage:** - **3. Blastocyst Formation:** - - - - - ### Stages of Cleavage Leading to Blastocyst Formation (with Diagrams): 1. 2. 3. 4. 5. Each of these stages can be visualized in a series of diagrams, showing the progression from a single-celled zygote to a blastocyst with differentiated cell types. ### Clinical Relevance and Key Points - - -