A STUDY OF THE EFFECT OF OVARIECTOMY, OESTROGEN AND PROGESTERONE ON THE MELANOCYTES AND MELANIN IN THE SKIN OF THE FEMALE GUINEA-PIG

Abstract

SUMMARY: 1. The effects of ovariectomy, oestrogen and progesterone on the melanocytes and melanin in the skin of the ear, anterior abdominal wall, areola, and sole of foot have been studied in pure black and pure red guinea-pigs. 2. Following ovariectomy the melanin content of the melanocytes was reduced and many of the melanocytes became smaller in size and had shortened dendritic processes. Some melanocytes had a deformed appearance, which varied from a minor irregularity of the cell contour to an advanced degree of cell collapse with fragmentation of the dendritic processes. A significant reduction of the melanocyte count occurred only in the areola, and this was accompanied by a reduction in the amount of free melanin. 3. In the ovariectomized animals which received oestrogen the amount of melanin was increased both inside and outside the melanocytes in all the regions. The greatest increase occurred in the areola where it was mainly due to a large increase of free melanin. In the nonsexual skin areas there was a smaller increase of free melanin but a greater increase in melanin within the melanocytes. No statistically significant changes in the counts were produced in any of the skin regions. 4. In the ovariectomized animals which received progesterone the amount and depth of colour of the melanin increased both within and outside the melanocytes and this was most marked in the ear. No statistically significant changes in the counts were produced in any of the skin regions. The general effect produced by progesterone was found to be less than that which occurred after oestrogen.