A small organelle or a larger organ consisting of organelles which produces substances and secretes these substances into the body (endocrinee secretion) or on body surfaces (exocrinee secretion).
Glands can be differentiated according to the type of secretion: * exocrine, e.g. sweat glandn, sebaceous glandn, mammary glands * endocrine, e.g. hormonal glands that release their secretion into the bloodstream
Differentiation according to construction: * tubular, tubular * acinous, grape-shaped * alveolar, vesicular
Unterscheidung nach der Viskosität des Sekretes:
https://de.wikipedia.org/wiki/Dr%C3%BCse (Wikipedia CC-by-sa-3.0)