Example

• Fertilization of the Ovum


  1. Sperm reach fallopian tube within 36 hours during female's ovulation period

  2. Egg ready for fertilization in fallopian tube

  3. Sperm cell penetrates ovum and releases enzymes at tip of head

  4. Nucleus of sperm and egg unite, forming zygote with 46 chromosomes

  
• Fertilization


  Fusion of nuclei and cytoplasm of haploid sperm and egg, forming diploid zygote

  
• Implantation


  Zygote becomes blastocyst that attaches to uterine wall
• Embryo


  Zygote after implantation
• Gametogenesis


  Production of sperm (spermatogenesis) and eggs (oogenesis) through meiosis
• Embryo


  Developing child during first two months of pregnancy

  
• Gastrulation


  Approximately three weeks after fertilization, forms three cell layers: ectoderm, endoderm, and mesoderm
• Amniotic sac formation


  Thin membrane forms around embryo during third week of pregnancy
• Organogenesis


  Three germ tissue layers develop into internal organs
• Fetus


  Developing child from third month of pregnancy onwards

  
• Fetal development (Second Trimester)


  • Fingers, eyes, toes, arms, and legs have developed

  
• Fetal development (Third Trimester)


  • Rapid growth, stronger bones and muscles

  
• Birth process


  Onset of labor, muscular contractions of uterus