Early Embryonic Development

Zygote

Initial cell formed by the ovum and a sperm cell (DNA derived from both parents)

Cleavage

The division of cells in the early embryo

Blastomeres

The cells derived from cleavage and from the Morula

Morula

The point when the cell has divided into 32 cells

Gastrulation

The blastula is re-organised into three layers called the gastrula

Ectoderm

Mesodem

Endoderm

Blastocyst

The cells of the morula secrete a liquid and the enveloping cells become the blastocyst (outside/placenta, inside/foetus)

Ectoderm: develops into skin and neural tissue

Mesoderm: develops into skeleton and cardiac tissue

Endoderm: develops into digestive and respiratory system