Hidesuke Fujita

Electron microscopic studies of most cells of human fetal skins

Electron microscopic study of human fetal skins revealed thick-type and elongated-type mast cells which seem similar to those in postpartum skin. Four types of mast cell granules were distinguished in these mast cells: granules presumed to be in mid-stage of maturation, with internal structures not contained inside a membrane-limited vacuole; granules of an undetermined nature, with internal structures contained inside a membrane-limited vacuole; electron dense granules presumed to be fully mature; compound-form granules presumably representing lysosomal structures. Among these granules, structures probably representing an earlier stage of granule formation were found. They consisted of membranous components, coarse granular components, and fine granular components. Based on the morphology of these granules and structures, a sequence in granule formation was postulated. Ultrastructural comparison between mast cells and dermal melanocytes in the same fetal skins revealed that these two mesenchymal cells were similar but not identical in the process of specific granule formation.

STUDY ON THE ULTRASTRUCTURE AND MUCIN PRODUCTION IN PRETIBIAL MYXEDEMA

Electron microscopic study on pretibial myxedema lesions revealed that, mucin consisted of three types of substances: (1) filamentous to finely granular or amorphous substances, (2) spidery projections extending from a granular core, and (3) fine granules arranged in beaded form. In the lesions, there were numerous mesenchymal cells referred to as the M‐cells which were not found in the normal skin and seemed to be participating in the production and extrusion of the first type of substance and possibly the precursor substances of the other two composing mucin. Most of them were two to three times larger in size than ordinary mast cells. Their cytoplasm displayed, like that of goblet cell, many mitochondria, well developed rough and smooth endoplasmic reticulum, and prominent Golgi apparatus accompanied by various lysosomal structures.

THE GLYCOLIPIDS OF NORMAL HUMAN SKIN

Glucosylceramide (CMH), lactosylceramide (CDH), ***trihexosylceramide (CTH), Globoside I, GM3, and GD3 were detected as constituent sphingoglycolipids of normal human skin, using Unisil, DEAE‐Sephadex, Iatrobeads column chromatography, and reversed‐phase chromatography. These procedures enabled isolation of glycolipids from even small amounts of skin.

A PECULIAR CORPORAL PIGMENTATION—A PRESUMED VARIANT OF ACROPIGMENTATIO RETICULARIS (KITAMURA)

We present a 52‐year‐old woman with peculiar pigmentation distributed mainly on the trunk, which morphologically and histopathologically resembled the lesion of acropigmentatio reticularis (Kitamura). Ultrastructural as well as histopathological findings suggested that the lesion of the present case may be regarded as a kind of inflammatory process induced by an immune mechanism against some components of keratinocytes or melanosomes.