Monilethrix: an electron microscopic and electron histochemical study.

We have carried our electron microscopic and electron histochemical investigations on affected hair follicles and hair shafts to elucidate further the structural abnormality in monilethrix. The structural abnormalities manifest in the cortex and cuticle of the hair shaft could be traced to the locality of the 'zone of keratinization' of the follicle. Abnormal orientation of the cortical cell proteins, folding of the cuticle cell membrane and varying amounts of endocuticular material were all observed in the region prior to full keratinization. We observed structural abnormalities within all the component layers of the inner root sheath adjacent to the faults within the hair shaft, indicating a possible asynchrony within the monilethrix follicle.