Editing Gland (section)

==Structure==
{{See also|List of glands of the human body}}

===Development===
[[File:Types Arrangements of Glands 1.png|thumb|This image shows some of the various possible glandular arrangements. These are the simple tubular, simple branched tubular, simple coiled tubular, simple acinar, and simple branched acinar glands.]]
[[File:Types Arrangements of Glands 2.png|thumb|This image shows some of the various possible glandular arrangements. These are the compound tubular, compound acinar, and compound tubulo-acinar glands.]]
Every gland is formed by an ingrowth from an [[epithelium|epithelial]] surface. This ingrowth may in the beginning possess a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated.<ref name=EB1911>{{EB1911 |wstitle=Epithelial, Endothelial and Glandular Tissues |volume=9 |pages=705–707 |inline=1}}</ref>

As growth proceeds, the column of cells may split or give off offshoots, in which case a compound gland is formed. In many glands, the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another. One exception to this rule is the [[liver]]; this occurs when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming the terminal portion of each branch, and the uniting portions form ducts and are lined with a less modified type of epithelial cell.<ref name=EB1911/>

Glands are classified according to their shape.
* If the gland retains its shape as a tube throughout it is termed a [[tubular gland]].
* In the second main variety of gland the secretory portion is enlarged and the [[lumen (anatomy)|lumens]] variously increased in size. These are termed [[alveolar gland|alveolar]] or saccular glands.<ref name=EB1911/>