What are the main components of a basement membrane, and which type predominates in glomerular basement membranes?

What are the main components of a basement membrane, and which type predominates in glomerular basement membranes?

• A. Basal lamina (type IV collagen and laminin) and reticular lamina (type III collagen); glomerular basement membrane contains type IV collagen primarily.
• B. Basal lamina (type I collagen) and reticular lamina (type II collagen); glomerular basement membrane contains type I collagen primarily.
• C. Basal lamina (type II collagen) and reticular lamina (type IV collagen); glomerular basement membrane contains type II collagen primarily.
• D. Basal lamina (type III collagen) and reticular lamina (type I collagen); glomerular basement membrane contains type III collagen primarily.

Answer: (A)

Basement membranes have two layers: the basal lamina, which sits closest to the epithelium, and the reticular lamina, produced by connective tissue. The basal lamina is built mainly from type IV collagen and laminin, forming a supportive meshwork, while the reticular lamina contains more type III collagen. In the kidney’s glomerulus, the glomerular basement membrane is a fused basal lamina between endothelial cells and podocytes, and it is predominantly type IV collagen. This makes the description that pairs basal lamina with type IV collagen and laminin, reticular lamina with type III collagen, and notes that the glomerular basement membrane contains type IV collagen primarily, the best fit.

Basement membranes have two layers: the basal lamina, which sits closest to the epithelium, and the reticular lamina, produced by connective tissue. The basal lamina is built mainly from type IV collagen and laminin, forming a supportive meshwork, while the reticular lamina contains more type III collagen. In the kidney’s glomerulus, the glomerular basement membrane is a fused basal lamina between endothelial cells and podocytes, and it is predominantly type IV collagen. This makes the description that pairs basal lamina with type IV collagen and laminin, reticular lamina with type III collagen, and notes that the glomerular basement membrane contains type IV collagen primarily, the best fit.