| A | B |
|---|
| totipotent | contains all the information needed to construct an entirely new organism |
| differentiation | specialization of cells through differential gene expression |
| morphogenesis | establishment of body axes and development of local structures such as limbs |
| gastrula | developmental stage in which distinct embryonic tissue layers are established |
| Hox genes | help establish the cell fates of individual body segments during development |
| Gastrulation | the inward migration of cells of the blastula, leading to the formation of distinct tissue layers |
| Cleavage | a series of mitotic cell divisions, without growth, that subdivide the zygote into a large number of small cells |
| Organogenesis | the formation of organs |
| fertilization envelope | Surrounds the zygote to help prevent additional sperm from fertilizing the egg |
| yolk | provides nutrients for the growing embryo, SLOWS CLEAVAGE |
| animal pole | Less yolk (faster cleavage) forms into the anterior end |
| vegetal pole | Most of the yolk is concentrated here, develops into the posterior |
| blastomeres | cells originating from cleavage |
| blastula | Hollow ball of cells (blastomeres) at early development |
| blastocoel | The internal cavity of the blastula |
| blastodisc | The Flattened blastula that sits on top of the yolk in chickens |
| Protostomes | mouth first development, exhibit spiral cleavage and determinant development |
| Dueterostomes | anus first development, exhibit radial cleavage and indeterminate development |
| Invagination | Inward migration of cells |
| Ectoderm | Lines the outside of the gastrula, develops into the epidermis, hair, brain, peripheral nervous system |
| Endoderm | Lines the internal body cavity, develops into the lining of the digestive system including the liver and pancreas, respiratory system, urinary system |
| Mesoderm | Lines the Coelem, develops into the skeletal, muscular, and pulmonary systems |
| Coelom | Fluid filled body cavity, present only in triploblastic organisms, Pinches off the archenturon in deuterostomes |
| Neurulation | the stage of organogenesis in vertebrate embryos, during which the neural tube is transformed into the primitive structures that will later develop into the central nervous system |
| Induction | the process whereby substances secreted by one group of cells influence development of neighboring cells |
| notochord | (mesoderm) a rodlike structure unique to chordates, signals the development of the neural plate through induction |
| neural folds | Fold up from the neural plate to create the neural tube |
| neural crest cells | originate at the interface between the neural folds and neural plate, develop into facial bones and neurons and other important structures |
| neural plate | (ectoderm) Forms after induction from the notochord |
| Somites | (mesoderm) blocks of cells located to either side of the spinal cord that later develop into the vertebrae, associated muscles and other tissues |
| Larva | First stage of Sea-star development, bilateral |
| Archenteron | Embryonic gut, formed after invagination, lined by endoderm |
| Blastopore | Entrance to the Archenteron |
| Yolk Plug | a patch of large endodermal cells which remains exposed on the vegetal surface of the amphibian blastula that will eventually be internalized |
| primitive streak | The linear axis of the blastodisc that gastrulation occurs along, Homologous to the blastopore |
| albumin | The protein rich egg white |
| amniotic egg | Contains four extraembryonic membranes, important evolutionary step for animals |
| Amnion | surrounds the amniotic cavity – a fluid-filled space immediately surrounding, and cushioning, the embryo proper. |
| Yolk Sac | : surrounds the yolk and facilitates transfer of nutrients between the yolk and the embryo proper via an extensive network of blood vessels (vitelline arteries and veins). |
| Allantois | : has two main roles: the cavity is a reservoir for metabolic wastes and the membrane serves as an exchange surface for respiratory gases |
| Chorion | the chorionic membrane eventually surrounds all other membranes and lies just beneath the shell, fuses with the allantois and helps gas exchange |
