Medically reviewed by Sanja Jelic, MD As we sleep, our brain moves through four stages and two phases: non-rapid eye movement ...

“We thought, could it be that the menstrual cycle, [what] we call estrous ... labeled tumor cells in a mouse model of breast cancer, they found that tumor cell populations expanded during the estrus ...

We call this a life cycle. As you grow older, how you look will change a lot ... This is called the larva stage. It doesn't look much like a butterfly yet, does it? Eventually the caterpillar ...

Different models of cell cycle regulation converged when scientists realized that different model organisms shared the same molecules. See how data from frogs and yeast were reconciled.