What are the two main components of the basement membrane?

• A. Basal lamina and reticular lamina
• B. Keratin and collagen
• C. Basement layer and deep lamina
• D. Basement membrane and submucosa

Answer: (A)

The basement membrane is made of two layers: the basal lamina and the reticular lamina. The basal lamina, secreted by epithelial cells, is a thin, dense sheet rich in laminin and type IV collagen that sits closest to the epithelium and provides adhesion and a selective barrier. The reticular lamina, produced by underlying connective tissue fibroblasts, contains fibrous components like type III collagen and helps anchor the basement membrane to the surrounding stroma, giving structural support. Together they form a cohesive, supportive bridge between epithelium and connective tissue. The other options don’t fit because they either name proteins not organized as these two laminas or refer to tissue layers that aren’t part of the basement membrane structure.