Changes in Fibronectin, Laminin, and Type IV Collagen Distribution Relate to Basement Membrane Restructuring During the Rat Vibrissa Follicle Hair Growth Cycle

The study investigated the distribution of fibronectin, laminin, and type IV collagen during the rat vibrissa follicle growth cycle, focusing on their role in basement membrane restructuring. Laminin and type IV collagen were consistently present at the dermal-epidermal junction and within the dermal papilla, with changes in their distribution observed during different hair cycle phases. Fibronectin was abundant in the anagen phase but showed heterogeneous staining at telogen. These changes in extracellular matrix distribution were linked to modifications in basement membrane ultrastructure, suggesting that the lower vibrissa follicle can rapidly remodel its basement membrane, facilitating dermal-epidermal signaling. The findings indicated that dermal papilla cells might contribute to basement membrane formation and that fibronectin could regulate cellular activities within the follicle, highlighting dynamic cellular activity throughout the hair cycle.