The electron microscope has been used in hair research for half a century, but the knowledge gained through this study has become rather fragmented over the years. While the molecular biological study of hair has become an active field, even here, as in more traditional research, an understanding of the morphological aspects is essential because the hair follicle structure is highly complex. The author explicates the structure, development, and differentiation of the hair follicle, using his own original photographs and explanations of current research, including growth factors, differentiation-inducers, cell signaling pathways, and transcription factors. With neonatal rats as subjects, he focuses on the morphological analysis of all basic hair cells - in the shaft, matrix, and papilla - from birth to death. The introductory chapter will benefit novices, with the following sections consisting mainly of explanations of the electron microscopic photographs of hair cells.