SEROUS ACINUS – 1
This and the following pages will analyze the serous acinus (plural: acini), a type of exocrine secretory unit that, as the mucous tubule, is widely found in several places of the body.
In the digestive system, for example, it forms small glands in the tongue and cheek wall as well as large glands such as the parotid gland and the pancreas.
The secretory product of the serous acini is usually fluid and rich in proteins. Many of them are important digestive enzymes that break nutrients down into smaller molecules, easing their absorption in the intestines.
Unlike the mucous tubules, the serous acini are rounded or oval and mostly not branched.
Their cells are usually pyramidal. Their flat apical surface (also called free surface) faces the acinar lumen. Although this drawing shows a relatively wide lumen, in sections the lumen may often appear narrow and difficult to observe, unlike the more dilated lumen of the mucous tubules.
The cytoplasm of the serous cells is usually well stained, mostly orange with eosin, due to the presence of numerous secretory vesicles stored in the apical part of the cell (also informallys called “over the nucleus”). In some organs such as in the pancreas, the basal (lower) part of the cytoplasm stains well with hematoxylin because it contaisn a great amount of RNA in ribosomes of its rough endoplasmic reticulum.
The nuclei are spherical and placed closer to the basal region of the cell.
Each acinus has a small and narrow excretory duct that in some glands, such as the pancreas, may not be easily observed in sections.
In the digestive system, for example, it forms small glands in the tongue and cheek wall as well as large glands such as the parotid gland and the pancreas.
The secretory product of the serous acini is usually fluid and rich in proteins. Many of them are important digestive enzymes that break nutrients down into smaller molecules, easing their absorption in the intestines.
Unlike the mucous tubules, the serous acini are rounded or oval and mostly not branched.
Their cells are usually pyramidal. Their flat apical surface (also called free surface) faces the acinar lumen. Although this drawing shows a relatively wide lumen, in sections the lumen may often appear narrow and difficult to observe, unlike the more dilated lumen of the mucous tubules.
The cytoplasm of the serous cells is usually well stained, mostly orange with eosin, due to the presence of numerous secretory vesicles stored in the apical part of the cell (also informallys called “over the nucleus”). In some organs such as in the pancreas, the basal (lower) part of the cytoplasm stains well with hematoxylin because it contaisn a great amount of RNA in ribosomes of its rough endoplasmic reticulum.
The nuclei are spherical and placed closer to the basal region of the cell.
Each acinus has a small and narrow excretory duct that in some glands, such as the pancreas, may not be easily observed in sections.
