Stages of Development
A single sperm penetrates the mother’s egg cell, and the resulting cell is called a zygote. The zygote contains all of the genetic information (DNA) necessary to become a child. Half of the genetic information comes from the mother’s egg and half from the father’s sperm. The zygote spends the next few days travelling down the fallopian tube and divides to form a ball of cells. The term cleavage is used to describe this cell division.
When the zygote reaches 16 or more cells, it is called a morula. The morula is no late get than the zygote, but keeps producing smaller and smaller cells through cleavage.
The morula continues to divide, creating an inner group of cells with an outer shell. This stage is called a blastocyst and consists of approximately 100 cells (taking around four to five days to develop). The inner group of cells will become the embryo, while the outer group of cells will become the membranes that nourish and protect it.
The blastocyst reaches the uterus around day five, and implants into the uterine wall on about day six. The cells of the embryo now multiply and begin to take on specific functions resulting in the various cell types that make up a human being (e.g. blood cells, kidney cells, and nerve cells).
Getting it right
Pregnancy is a complicated process that depends upon many factors and there is no need to write further like:
- The production of healthy sperm by the man and healthy eggs by the woman.
- You need to have regular sexual intercourse during your fertile time.
- Normal Female reproductive system.
- Unblocked Fallopian tubes that allow the sperm to reach the egg.
- You need to ovulate.
- A genetically healthy embryo.
- The ability of the embryo to implant in the uterus.
After fertilisation, the egg now known as an embryo, develops in the fallopian tube for the first three days, then travels down into the uterus. By the fifth day it become a blastocyst. Once the blastocyst breaks free from its shell, or hatches, it is ready to adhere to the surface of endometrium.
It begins to secrete human chorionic gonadotrophin (hCG), a hormone that tells the corpus luteum to continue progesterone production. A home pregnancy test will detect hCG by Day 28 of a menstrual cycle.