11.4  Sexual Reproduction

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Essential Idea:

Sexual reproduction involves the 

development and fusion of haploid gametes


  • Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation
  • Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm
  • Fertilization in animals can be internal or external
  • Fertilization involves mechanisms that prevent polyspermy
  • Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy
  • hCG stimulates the ovary to secrete progesterone during early pregnancy
  • The placenta facilitates the exchange of materials between the mother and fetus
  • Estrogen and progesterone are secreted by the placenta once it has formed
  • Birth is mediated by positive feedback involving estrogen and oxytocin


  • The average 38-week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals


  • Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis
  • Annotation of diagrams of mature sperm and egg to indicate functions