A fertilized ovum.

A ball of cells with a cavity in the center.

A solid ball of cells resulting from division of a fertilized ovum.

An implanted blastocyst from the time of implantation until about the eighth week of development.

A developing baby from the end of the eighth week after fertilization until birth.

A fluid filled structure that surrounds the embryo.

A structure that forms along the lining of the uterus as the embryo implants.

A rope like structure that connects the embryo and the mother's placenta.

Units of heredity that determine which traits, or characteristics, offspring inherit from their parents.

A process in which genetic histories of prospective parents are studied to determine the presence of certain hereditary diseases.

The sperm and ovum each contribute one set of ___ chromosomes during fertilization.

Ova always carry an ___ chromosome.

Sperm may carry an X or Y chromosome.

X is a ___ chromosome.

Y is a ___ chromosome.

If a sperm carrying an X chromosome fertilizes an ovum the child will be a ___

If a sperm carrying a Y chromosome fertilizes an ovum, the child will be a ___.

An XX combination results in a ___.

An XY combination results in a ___.