Fertilization

Zygote

          Cleavage

Morula

Blastula

          Blastocyst

Gastrulation

Germ layers

          Ectoderm

          Mesoderm

          Endoderm

Organogenesis

          Neurulation

                    Neural tube

Human chorionic gonadotropin - hCG

Placenta

First Trimester

          Teratogens

Second Trimester

Third Trimester

Gestation period

Dilation

Expulsion

          Oxytocin

Placental

Fetus in Fetu

Zygote -->(Cleavage) -->Morula -->Blastocyst -->(Gastrulation) Gastrula -->(Organogenesis) Embryo