The basal lamina visible on electron microscopy is produced by the overlying epithelium and is distinct from the underlying reticular lamina. Which component of the basal lamina is synthesized by the epithelial cells themselves?

• A Type III collagen
• B Fibronectin secreted by fibroblasts
• C Type I collagen
• D Type IV collagen and laminin ✓

Explanation

The basal lamina is an epithelial product containing type IV collagen, laminin, entactin (nidogen) and heparan sulfate proteoglycan (perlecan). The reticular lamina beneath it contains type III collagen made by fibroblasts, which is why silver stains highlight reticular fibers but not the basal lamina itself.

Reference: Junqueira's Basic Histology: Text and Atlas, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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