Reproduction and Development
Science

A developing mammal embryo that consists of a hollow ball of cells
Blastocyst
A developing mammal embryo that consists of a hollow ball of cells. Blastocyst. In simple terms, a blastocyst is an early stage in mammalian development when the embryo is a tiny, hollow ball of cells ready to implant in the uterus.

An ovarian follicle after ovulation, also called a yellow body for its yellow color
Corpus luteum
An ovarian follicle after ovulation, also called a yellow body for its yellow color, is known as the corpus luteum. The corpus luteum is a temporary structure in the ovary that produces hormones to support early pregnancy.

The cell migration process that forms a third layer within the blastocyst cavity
Gastrulation
The cell migration process that forms a third layer within the blastocyst cavity. Gastrulation. Gastrulation is when an embryo's cells reorganize to form three basic layers, which are essential for developing different tissues and organs.

The organs used in sexual reproduction, like the uterus in females and testes in males
Reproductive system
The organs used in sexual reproduction, like the uterus in females and testes in males, reproductive system. The reproductive system is the group of organs and structures that work together to enable reproduction and produce offspring.

A disease that is spread through sexual contact, like AIDS or herpes
Sexually transmitted disease
A disease that is spread through sexual contact, like AIDS or herpes. Sexually transmitted disease. A sexually transmitted disease STD is an infection that is passed from one person to another through sexual activity.