A Contemporary View on Felix Pinkus’ Concept of the Vitreous Membrane

The document examined the vitreous membrane (VM) in hair follicles, a concept originally proposed by Felix Pinkus in 1927. Through histological and immunohistochemical analysis of skin samples from 11 patients, researchers observed morphological variations in the VM, such as protrusions and folds, which may play a role in hair follicle differentiation, nutrition, or could result from pressure from growing hair shafts. The study also described the VM's changes during the hair cycle and suggested that the VM, along with the outer root sheath and fibrous sheath, adjusts to the hair cycle's phases, expanding and contracting like a concertina. Protrusions into the outer root sheath, accompanied by perifollicular tissue and a VM coating, could enhance nutrient exchange by increasing the surface area for diffusion. The research was approved by an ethics committee and conducted without funding.