| A | B |
|---|
| Embryo | In the early stages of development, the organism is called an |
| Cleavage | Is a series of mitotic divisions where the cell increases in cell number but NOT in cell size |
| Blastula | As cleavage continues, the cells form a hollow ball-type structure filled with fluid called a |
| Gastrula | Once the blastula forms, the cells on one side of the blastula push in and form a two-layered embryo called the |
| Gastrulation | The process in which a blastula forms into a gastrula is known as |
| Differentiation | Is a series of changes that transform the unspecialized embryonic cells into specialized cells, tissues and organs |
| Growth | The term defined as not only are the number of cells increasing, but the size of the cells are increasing as well, and the embryo as a whole starts to develop |
| External Development | Development occurs outside the female body |
| Yolk | In External development, nourishment for the developing embryo is supplied by the |
| Amnion | A sac containing amniotic fluid which surround the embryo, provides cushion and acts as a shock absorber |
| Internal development | This development occurs inside the female |
| Uterus | A structure used for internal development |
| Placenta | Provides nourishmant and the oxygen for the developing embryo |
| Umbilical cord | attaches the embryo to the placenta |
| Masupials | Are mammals that do not have a placenta |
| Ectoderm | Gives rise to the nervous system and skin |
| Endoderm | Gives rise to the lining of the digestive tract and organs like the liver |
| Mesoderm | Gives rise to bones and muscles |
