Pregnancy

• Events pre-fertilization


  Chemotaxis

  The egg cell membrane breaks down

  Sperm head enters the egg

  Fertilization

  Protective coat formation
• Events after fertilization


  The diploid zygote travels down the fallopian tube.

  It divides by mitosis many times to form the morula.

  Five days after fertilisation the morula becomes a blastocyst
• Copulation


  The insertion of the penis into the vagina
• Ejaculation


  The release of sperm from the penis
• Insemination


  The release of semen into the vagina below the cervix.
• Fertilization


  The fusion of the nucleus of the sperm with the nucleus of the egg in the fallopian tube forms a diploid zygote.
• Morula


  A solid ball of cells, produced by mitosis of the zygote.
• Blastocyst


  A hollow ball of cells developed from the morula.
• Trophoblast


  The outer layer of the blastocyst. This develops into the placenta.
• Inner Cell Mass


  This is the inner layer of the blastocyst, and it develops into the embryo.
• Implantation


  The embedding of the blastocyst into the lining of the uterus (the endometrium). The blastocyst now becomes an embryo.
• Amnion


  A protective membrane that forms around the embryo and secretes amniotic fluid, which acts as a shock absorber.
• Placenta formation

  Chorion formation

  Villi formation

  Placenta is connected to embryo by umbilical cord
• What does the outer layer/trophoblast of the blastocyst turn into?

  Placenta
• What does the inner layer of the blastocyst turn into?

  Embryo
• Implantation


  The embedding of the blastocyst into the lining of the uterus (the endometrium)
• Amnion


  A protective membrane that forms around the embryo and secretes amniotic fluid, which acts as a shock absorber.
• What is the outermost germ cell layer and what does it form?

  Ectoderm + hair, skin, nails, nervous system
• What is the middle germ cell layer and what does it form?

  Mesoderm + Ciruculatory, respiratory, excretory, and musculoskeletal system
• What is the innermost germ cell layer and what does it form?

  Endoderm + liver, gut, lining of respiratory digestive and excretory system
• What is gestation?


  The time period from pregnancy until birth. It lasts approximately 40 weeks.
• Vasectomy


  The sperm ducts are cut and tied to prevent sperm from being in male semen and without sperm, fertilisation cannot occur.
• What is in-vitro fertilization?


  The process where fertilization takes place outside the male and female reproduction systems, in a laboratory with controlled conditions.