| Alveolar gland |
Alveolar glands, also called saccular glands, are glands with a saclike secretory portion, in contrast with tubular glands. They typically have an enlarged lumen (cavity), hence the name: they have a shape similar to alveoli, the very small air sacs in the lungs.
Some sources draw a clear distinction between acinar and alveolar glands, based upon the size of the lumen.[1] A further complication in the case of the alveolar glands may occur in the form of still smaller saccular diverticuli growing out from the main sacculi.
The term "racemose gland"[2] is used to describe a "compound alveolar gland" or "compound acinar gland."[3]
Branched alveolar glands are classified as follows:
| Type | Description | Location | |||||
|---|---|---|---|---|---|---|---|
| valign=top | simple branched acinar | valign=top | valign=top | thyroid glands | |||
| valign=top | tubuloalveolar or tubulo-alveolar or tubulo-acinar or compound tubulo-acinar or compound tubuloalveolar | valign=top | glands that start out as simple branched tubular, and branch further to terminate in alveoli | valign=top | salivary glands,[4] esophagus mammary glands |