An Electronmicroscopic Study of the Epidermis of the Transitional Skin in the Human Anal canal

In the epidermis of the lower part of the human zona haemorrhoidalis, fine structures of the stratum basale, spinosum, granulosum, and corneum were electronmicroscopically observed.The basement membrane was 200-300 A thick and combined with the connective tissue of the corium by fine fibrils. The basal cell had an oval nucleus and its cytoplasm contained relatively well developed organelles, melanin granules, and tonofilaments mainly running perpendicularly to the surface of the epidermis. In the stratum spinosum, multiple, better developed organelles, especially Golgi complex and ribosomes, were observed and the intercellular spaces were more wide. The tonofilaments in this layer were concentrated closely to form the tonofibrils. The cell of the granular layer became to be flat in shape as they close to the horny layer. The organelles in this cell decreased in number and some of them were degenerated, but were thought to be still better preserved than those of other general epidermis. The stratum corneum was subdivided into two layers. The deep one was piled with 2-5 flat cell layers and showed the keratin pattern; the surface layer, consisted of 7-10 cell layers, had an appearance of the diffuse irregular network of gross filaments.In the outer region of the spinous layer and in the granular layer, round, smooth-surfaced granules with moderate density (so-called membrane-coating granules), measuring about 0.1μ in diameter, were found numerously in the cytoplasm. It was seemed that they were delivered from the Golgi vacuoles, and it was suggested that these granules might be associated with the production of the pale homogenous substances in the intercellular spaces of the stratum corneum.