Sexual Reproduction in Humans

The Menstrual Cycle

  • A 28 day cycle where the egg is released (ovulation) and the uterus is prepared to receive a fertilised egg.
  • If the egg is not fertilised then the uterus will shed its lining as menstrual flow (sometimes called a period).
  • Day 1 of the cycle is the first day of menstrual flow
  • Ovulation occurs on day 12
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Endometriosis

The first 45 seconds illustrate the shedding of the lining of the uterus

Development of the Fetus

Stages of development

There are names for each stage of the development of the fetus that you need to know.


Development of the EMBRYO begins after fertilisation has occurred.


  • Zygote - the first cell
  • Blastocyst - the group of first cells after day 5


After around week 8 the embryo is now known as a FETUS


The difference between an embryo and a fetus is that the enbryo is more about the formation of organs and limbs. The development of the fetus is more about growth (the embryo getting bigger).