Orderly, genetically programmed changes in the size, shape, and proportion of body parts of an organism; the process by which specialized tissues and organs form.

The end of the egg where the egg nucleus is located, which typically gives rise to surface structures and the anterior end of the embryo.

Mitotic cell divisions of the zygote that produce a blastula from a fertilized ovum.

A small cell formed during cleavage of the embryo.

The hollow ball of cells that is the result of cleavage divisions in an early embryo.

The developmental stage resulting when the cells of the blastula migrate and divide once cleavage is complete.

The three primary cell layers of the embryo: the outer ectoderm, the inner endoderm, and the mesoderm between the ectoderm and the endoderm.

The innermost of the three primary germ layers of an embryo, which develops into the gastrointestinal tract and, in some animals, the respiratory organs.

In development, referring to cells derived from totipotent cells; pluripotent cells can give rise to most adult cell types.

A mechanism in which cells make and break specific connections to other cells or to the extracellular matrix.

A mechanism in which one group of cells (the inducer cells) causes or influences another nearby group of cells (the responder cells) to follow a particular developmental pathway.

Process by which cells that have been committed to a particular developmental fate by the determination process now develop into specialized cell types with distinct structures and functions.

The process in which cells changing shape and pushing inward from the surface produce an indentation, such as the dorsal lip of the blastopore.

A disclike layer of cells at the surface of the yolk produced by early cleavage divisions.

In development of birds, the sunken midline of the primitive streak that acts as a conduit for migrating cells to move into the blastocoel.

A primary tissue layer extended outside the embryo that conducts nutrients from the yolk to the embryo, exchanges gases with the environment outside the egg, or stores metabolic wastes removed from the embryo.

In an amniote egg, an extraembryonic membrane that encloses the yolk.

In an amniote egg, an extraembryonic membrane that encloses the embryo, forming the amniotic cavity and secreting amniotic fluid, which provides an aquatic environment in which the embryo develops.

In an amniote egg, an extraembryonic membrane sac that fills much of the space between the chorion and the yolk sac and store's the embryo's nitrogenous wastes.

Ectoderm thickened and flattened into a longitudinal band, induced by notochord cells.

A hollow tube in vertebrate embryos that develops into the brain, spinal cord, spinal nerves, and spinal column.

A band of cells that arises early in the embryonic development of vertebrates near the region where the neural tube pinches off from the ectoderm; later, the cells migrate and develop into unique structures.

Paired blocks of mesoderm cells along the vertebrate body axis that form during early vertebrate development and differentiate into dermal skin, bone, and muscle.

An embryonic stage in mammals; a single-cell-layered hollow ball of about 120 cells with a fluid-filled blastocoel in which a dense mass of cells is localized to one side.

The dense mass of cells within the blastocyst that will become the embryo.

One of many treelike extensions from the chorion, which greatly increase the surface area of the chorion.

A long tissue with blood vessels linking the embryo and the placenta.

The process of giving birth.

Navel; the scar left when the short length of umbilical cord still attached to the infant after birth dries and shrivels within a few days.

The bipotential primitive duct associated with the gonads that leads to a cloaca.

A cell surface protein responsible for selectively binding cells together.

A cell surface protein responsible for selective cell adhesions that require calcium ions to set up adhesions.