Cell Differentiation in the Lower Outer Sheath of the Romney Wool Follicle: A Companion Cell Layer

Abstract

Morphological evidence is presented showing that, in the Romney wool follicle, the layer of cells in the outer root sheath lying next to Henle's layer differentiates in the bulb as a separate and distinct layer from other outer root sheath cells. The term "companion cell layer" is suggested for this layer. Its possible role in the movement of the inner root sheath toward the skin surface is discussed.