Beyond fertilisation

By sdagar1
  • Fertilisation

    The fertilised ovum becomes a zygote and continues to travel along the oviduct, whilst dividing my mitosis.
  • The morula

    The morula
    After 3-4 days it has formed a ball of cells called a morula. It looks a bit like a blackberry. The dividing cells are surrounded by a jelly coat. It continues to move down the oviduct towards the uterus helped by the action of cilia which create a steady flow of fluid towards the uterus.
  • The blastocyst

    The blastocyst
    By about days 5-6 the morula has turned into a blastocyst. The blastocyst is a hollow ball of cells which are continuing to divide by mitosis. Just inside the jelly coat there is a outer layer of cells called the trophoblast. The trophoblast will go onto become the start of the placenta. The cells inside the hollow ball will go onto form the embyro.
  • Arrival at the uterus

    Arrival at the uterus
    On day 6-7 the blastocyst will arrive at the uterus.
  • Implantation

    When the blastocyst reaches the endometrium, the jelly coat lyses (breaks).
  • Implantation 2

    Implantation 2
    The trophoblast cells which are touching the endometrium cause the endometrium to inflame and start to interact with the trophoblast. The trophoblast cells form extensions called chorionic villi which secrete enzymes to break down the outer layer of the endometrium. This helps to release nutrients for the developing embryo. The placenta develops where the trophoblast and endometrium interact.
    During this the cells inside the the blastocyst are still dividing by mitosis.