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Fertilisation
The male gamete (sperm) and female gamete (ovum) unite and the ovum is fertilised by the sperm to form a zygote. The newly formed zygote undergoes mitosis, creating identical copies of itself in order to begin the next phase. -
Morula
After 2-4 days, the zygote has undergone mitosis and eventually reaches the point where there are 16 cells. This is known as a morula. The outside cells then differentiate into trophoblast cells and undergo a process known as compacting. -
Blastocyst
After the morula differentiates its outer cells into trophoblast cells, the remaining cells form a small mass, this is called the blastocyst. Within the empty space, there are species embryotic fluids and the small mass will grow to form the developing fetus whilst the outside, trophoblast cells will create a protective layer that shields the offspring. This occurs around 4-5 days after fertilisation -
Implantation
(Moving towards uterus) The blastocyst eventually reaches the uterus, where it can spend several days in until it finally implants itself into the endometrium. The blastocyst then releases hCG (human chorionic gonadotropin) in order to signal the corpus luteum to continue releasing progesterone and oestrogen. This is done in order to prevent menstruation, which itself is a process that can cause complications in pregnancy if it was to occur. Implantation can occur 8-12 days after fertilisation. -
Embryo
My info got deleted so im summarising. The blastocyst cells continue to rapidly develop, forming a fetus that has distinct tissues due to cell differentiation. This occurs around three weeks after fertilisation and ends at the period that marks eight weeks after fertilisation. -
Fetus
Eight weeks after fertilisation, the embryo is now considered a fetus. The fetus begins to develop organs and structures until it its born 9 months after fertilisation