Poster presentation, P23

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Transmission electron microscope of fetal scalp melanocytes

OBJECTIVE: To observe the melanocytes in fetal scalp, their dendrites, and the ultrastructure of the melanin granules found in these cells under transmission electron microscope. METHODS: Human fetal skin was obtained from induced abortion of 140-150 d estimated gestational age. The specimen was washed in PBS and fixed in 2.5% glutaraldehyde and 0.1 M phosphate buffer (pH 7.2) for at least 2 h. The postfixation was in 1% osmium tetroxide and same buffer for 1 h followed by staining for 30 min in 1% uranyl acetate and 50% ethanol. The specimen was dehydrated using serial alcohol and acetone incubations and then embedded in spurr resin. A Sorvall MT-2B ultramicrotome was used to cut the scalp to 80 nm. Sections were stained with uranyl acetate and lead citrate. Grids were viewed in a Hitachi H-7000 transmission electron microscope at an accelerating voltage of 80 kV. RESULTS: The melanocytes located in the epidermis of the fetal scalp presente as clear cytoplasm and heterochromatic nuclei with various stages of melanosomes, most of them were immature. These cells consisted of abundant mitochondrion, endocytoplasmic reticulum and ribosome. Melanosomes transferred to neighbouring keratinocytes were singly distributed. The melanocytes in the hair follicles were rare, only parts of two melanocytes were observed, which contained most II-III stages of melanosomes. In this study, we also observed the melanosomes which presenting as degradative conglomerates within phagocytic vacuoles of the keratinocytes. Neither individual premelanosomes nor melanosomes occurring free in the keratinocytes were observed. CONCLUSIONS: The ultrastructure of melanocytes in fetal hair follicles is different from that in epidermis. The degradative conglomerates within phagocytic vacuoles in keratinocytes in dermal papilla maybe suggest the fate of hair bulb melanocytes during hair cycle.

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