Endemic
1. Describing a plant or animal species whose distribution is restricted to one or a few localities.
2. Describing a disease or a pest that is always present in an area.

End-labelling
The introduction of a radioactive atom at the end of a DNA or RNA molecule. A commonly used method is to use T4 polynucleotide kinase to introduce a 32p atom onto the end of a DNA molecule
Endocrine gland
Any gland in an animal that manufactures hormones and secretes them directly into the bloodstream to act at distant sites in the body, known as target organs or cells. cf exocrine gland. See gland.

Endoderm
The internal layer of cells of the gastrula, which will develop into the alimentary canal (gut) and digestive glands of the adult.

Endodermis
(Gr. endon, within + derma, skin) The layer of living cells, with various characteristically thickened walls and no intercellular spaces, which surrounds the vascular tissue of certain plants and occurs in nearly all roots and certain stems and leaves. The endodermis separates the cortical cells from cells of the pericycle.

Endogamy
The fusion of reproductive cells from closely related parents, i.e., inbreeding. cf exogamy.