Page 249 - Veterinary Histology of Domestic Mammals and Birds, 5th Edition

Digestive system (apparatus digestorius) 231

nucleus rich in euchromatin. One distinct nucleolus is usu- phospholipids, triglycerides, cholesterol, cholesterol esters
VetBooks.ir ally present. Through amitosis, hepatocytes may contain and free fatty acids. The smooth ER also contributes to
two or more nuclei, depending on the functional status synthesis of steroid hormones and transformation and
of the cell. Hepatocytes contain abundant metabolically breakdown of sterols. The lipoproteins are assembled in
active organelles, reflecting the diversity of functions they the Golgi apparatus, enclosed in a membrane and exocy-
perform. tosed into the perisinusoidal space.
The dense network of rough endoplasmic reticulum The membranes of the smooth ER also serve in the
within hepatocytes is indicative of their role in protein modification, breakdown, detoxification and expulsion of
synthesis. The rough ER participates in formation and metabolic products and foreign substances (e.g. steroids,
transport of α- and β-globulins, ceruloplasmin, fibrinogen, drugs). Enzymatic detoxification involves processes such as
coagulation factors and cellular enzymes (e.g. glutamate acetylation, methylation, demethylation, reduction and/
dehydrogenase). These cellular products are continuously or oxidation.
processed by the Golgi apparatus and released into the A major function of the smooth ER is formation of
perisinusoidal space, from whence they reach the blood. bile. In this process, cholesterol is converted to bile acids
Smooth endoplasmic reticulum is diffusely distributed and bile salts, which are actively transported into the bile
in the cytoplasm (Figure 10.79). This is the site of lipopro- canaliculi together with water and bilirubin.
tein synthesis and detoxification of noxious substances. With respect to metabolic exchange, the key organelle
Individual substances produced by the smooth ER include within hepatocytes is the well-developed Golgi apparatus

10.74 Fine structure of a hepatocyte (horse; x6000).

10.75 Fine structure of the cytoplasm of a hepatocyte (horse; x14,000).

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