F1Ch14aa (lesion of NSJ, continued): The basic features, as might be seen in a normal follicle, seem to be accentuated; they are further distinguished (in the manner of a dysplasia) by asymmetrical patterns. It is of interest that these distorted follicular units of NSJ usually do not show a convincing outer root sheath. Some of the abnormal bulbs are attached to a constant component by a slender strand of indifferent squamous cells.
The site of origin of the cells of the outer root sheath is uncertain, if reliance is placed solely on histologic observations. A notion that it, like the inner root sheath, is derived from specific cells of the bulb should, at least, be considered. In the normal development of a follicle, a trail of glycogen-rich cells is left behind to mark the trail of the descent of the bulb. In turn, the developing hair shaft must invade this column of clear cells. Perhaps, a column of specialized clear cells facilitates, in some manner, the development of a hair shaft. If an absence of an outer root sheath is truly a feature of the follicles of NSJ, then the alopecia of NSJ might be a consequence of such a developmental defect.