Question

Smooth ER will be abundant in

• A. Thyroid
• B. Adipose tissue
• C. Adrenal cortex
• D. All of the above

Answer 1

The correct option is D All of the above

Lipid synthesis and storage and synthesis of cholesterol and steroid hormones are an important function of the smooth endoplasmic reticulum (SER). The SER membranes also appear to be involved in the formation of lipoprotein complexes. The SER is also implicated in the initial stages of the breakdown of fatty acids. Conversion of fatty acids to acetyl coenzyme A esters occurs mainly in ER. As the ER has been associated with storage of lipids, they are expected to occur in Adipose tissue. In the testes, ovary and the adrenal cortex the SER has a role in the synthesis of steroid hormones.
Some protein secretory cells have extensively developed arrays of Rough Endoplasmic Reticulum (RER) arranged in parallel stacks, as seen in the pancreatic acinar cells. The RER is distributed throughout the cytoplasm in plasma cells which synthesize and secrete immunoglobulin. Other cells may have RER mainly in an apical or basal orientation as in intestinal epithelial cells or thyroid follicular cells, respectively.