Also found in: Dictionary, Thesaurus, Medical, Wikipedia.


The small terminal sac of an acinous gland, lined with secreting cells.
An individual drupelet of a multiple fruit.



(1) A structural and functional unit or the terminal secretory portion of the salivary, pancreatic, lacteal, sebaceous, or other saccular (alveolar) glands. The acinus is a bubble-like formation of one or more types of gland cells situated on a basement membrane and surrounded by connective tissue, capillaries, and nerve fibers. The apexes of the cells with their microvilli are directed toward the chamber of the acinus into which the secretion is discharged.

(2) A part of the respiratory apparatus in mammals that includes a section of the lung corresponding to the branches of the terminal bronchus—that is, the bronchioles, alveolar passages, and alveoli. One pulmonary lobule consists of 12–18 acini.

References in periodicals archive ?
There was more cytoplasmic lipid accumulation seen in the acinus cells and some striated duct cells in DM group than the control group.
The first stage was the ripe stage, in which the acinus was compressed and elongated with an irregular shape ([+ or -]S.
For example, polymeric IgA, which is secreted by B-lymphocyte cells in close proximity to salivary cells, is then bound by IgA receptors present on acinus cells, and then gets released into saliva (34).
The acinus cells are with clear nuclei, chromatin is finely divided.
These cells formed a thick band around the periphery of each acinus and spermatozoa began to accumulate in the lumina of acini [ILLUSTRATION FOR FIGURE 1B-D OMITTED].
Rigid arches and punched-out space involving a single acinus in keeping with atypical ductal hyperplasia (hematoxylin-eosin, original magnification X40).
From the centre of such a bronchiole, a perpendicular was dropped to the edge of the Acinus (Connective tissue septum or pleura), and the number of alveoli cut by this line was then counted.
It is also suggested that minute channels are present between the demilunes cells and the mucous cells, which join with the lumen of the acinus.
The functional unit of the lung, the acinus, is composed of the terminal bronchiole and the air spaces it supplies (12).
7] Another theory is that the squamous changes in the breast probably begin within the myoepithelial cell layer, before eventually involving the entire acinus.
The gametogenic compartment is located among the tubules of the digestive gland; the acinus is its' basic morphological unit, having a globous appearance, and is found intimately interacting with the periacinar and interacinar compartments (Figs.