An element is a pure substance that is made from a single type of atom. Elements are the building blocks for all the rest of the matter in the world. Examples of elements include iron, oxygen, hydrogen, gold, and helium.
Since the initial discovery that the adult brain contains stem cells that generate new neurons, an important question in neurobiology has been whether or not this adult neurogenesis is functionally important.
1.2 Biology (Of a cell, part, or tissue) in the earliest stage of development: primordial germ cells. More example sentences. 1  Embryonic stem cells are primordial cells with the ability to morph into any type of cell in the body.2  During human fetal development, the primordial germ cells migrate to and are incorporated within the developing ovary and are termed oogonia. Embryonic stem cells are primordial cells with the ability to morph into any type of cell in the body. 2  During human fetal development, the primordial germ cells migrate to and are incorporated within the developing ovary and are termed oogonia.