Exocrine Gland Structure
Figure 5.30 shows a generalized multicellular exocrine gland—a structural arrangement found in such organs as the mammary gland, pancreas, and salivary glands. Most glands are enclosed in a fibrous capsule. The capsule often gives off extensions called septa, or trabeculae (trah-BEC-you-lee), that divide the interior of the gland into compartments called lobes, which are visible to the naked eye. Finer connective tissue septa may further subdivide each lobe into microscopic lobules (LOB-yools). Blood vessels, nerves, and the gland's own ducts generally travel through
Figure 5.30 General Structure of an Exocrine Gland. (a) The gland duct branches repeatedly, following the connective tissue septa, until its finest divisions end on saccular acini of secretory cells. (b) Detail of an acinus and the beginning of a duct.
Figure 5.30 General Structure of an Exocrine Gland. (a) The gland duct branches repeatedly, following the connective tissue septa, until its finest divisions end on saccular acini of secretory cells. (b) Detail of an acinus and the beginning of a duct.
these septa. The connective tissue framework of the gland, called its stroma, supports and organizes the glandular tissue. The cells that perform the tasks of synthesis and secretion are collectively called the parenchyma (pa-REN-kih-muh). This is typically simple cuboidal or simple columnar epithelium.
Exocrine glands are classified as simple if they have a single unbranched duct and compound if they have a branched duct. If the duct and secretory portion are of uniform diameter, the gland is called tubular. If the secretory cells form a dilated sac, the gland is called acinar and the sac is an acinus31 (ASS-ih-nus), or alveolus32 (AL-vee-OH-lus). A gland with secretory cells in both the tubular and acinar portions is called a tubuloacinar gland (fig. 5.31).
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