During gestation, in which stage are all of the major organs and structures within the developing mammal formed?
There are three general phases of gestation. The germinal stage is the period of gestation from fertilisation to implantation of the embryo in the uterus. The embryonic stage of gestation is the period after implantation, during which all of the major organs and structures within the growing mammal are formed. Once the embryo is fully formed, it expands, grows, and continues to develop during the foetal developmental stage. This is when the mother undergoes major physical changes and becomes visibly pregnant.