Sexual reproduction

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  • Sexual Production
    • spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation
      • oogenesis - production of egg cells
        • primary follicle
          • mature follicle
            • secondary oocyte
      • spermatogenesis - production of sperm
        • seminiferous tubules - narrow tubes
          • interstitial cells - interstices
            • germinal epithelium - outer layer of the cells
              • spermatozoa
                • Sertoli cells
    • Processes in speratogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm
    • fertilisation involves mechanisms to avoid polyspermy
      • Acrosome reaction - the zona pellucida is destroyed by the content of the acrosome when one sperm attaches to the egg
      • penetration of the egg membrane - sperm membrane binds to egg membrane and fuse together
      • cortical reaction - cortical granules avoid that other sperms fertilise the egg
    • fertilization in animals can be internal or external
    • implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy
    • hCG stimulates the ovary to secrete progesterone during early pregnancy
      • prevention of the distruction of the endometrium
    • the placenta facilitates the exchange of materials between the mother and the embryo
      • fetal tissues
      • placental villus
      • maternal blood flows in the inter villuos spaces around the villi
      • placental barrier
      • oxygen, carbon dioxide, glucose, antibodies, water
    • Estrogen and progesterone are secreted by the placenta once it has formed
    • Birth is mediated by positive feedback involving estrogen and oxytocin
      • oxytocin stimulates contractions of the muscle fibres
      • uterine contractions

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