Search Results
You are looking at 1 - 4 of 4 items for
- Author: R. S. SNELL x
- Refine by access: All content x
Search for other papers by R. S. SNELL in
Google Scholar
PubMed
SUMMARY
1. The effect of a commercial preparation of corticotrophin (Acthar gel, Armour Pharmaceutical Co. Ltd.) on the melanocytes and melanin in the skin of the anterior abdominal wall and areola has been studied in pure black and pure red male guinea-pigs. The hormone was injected subcutaneously in a dose of 0·4 i.u. once daily 5 days/week for 1 month.
2. The hormone produced a marked reduction in the amount of melanin in the melanocytes; the greatest effect was seen in the skin of the anterior abdominal wall. In half the specimens the amount of free melanin was also reduced. There was a tendency for a slight increase of the length and complexity of the dendritic processes. A statistical analysis of the melanocyte counts showed no change.
3. It is concluded that in the intact mammal corticotrophin inhibits melanogenesis probably indirectly by the release of cortisol from the suprarenal gland.
Search for other papers by R. S. SNELL in
Google Scholar
PubMed
SUMMARY
The effect of hydrocortisone acetate and adrenalectomy on the melanocytes and melanin in the skin of the anterior abdominal wall has been studied in pure black and pure red male guinea-pigs. The hormone was injected subcutaneously in doses of 1·6, 5 and 12·5 mg./day for 1 month into intact guinea-pigs and in doses of 2·5 mg./day into adrenalectomized guinea-pigs.
Biopsy specimens of skin were taken before and after the hormone treatment and were processed with the Dopa reagent; both skin sheets and vertical sections were examined. In the adrenalectomized animals a further specimen of skin was taken some time after the cessation of the hormone treatment.
Hydrocortisone and adrenalectomy produced no effect on the activity of the melanocytes. A statistical analysis of the melanocyte counts showed no change.
Search for other papers by R. S. SNELL in
Google Scholar
PubMed
SUMMARY
1. The effect of beta melanocyte stimulating hormone (β-m.s.h.) extracted from the posterior pituitary of the hog, on the melanocytes and melanin in the skin of the ear, anterior abdominal wall, areola and sole of foot has been studied in pure black and pure red intact male and ovariectomized female guinea-pigs. The hormone was injected subcutaneously twice daily 5 days/week for 1 month.
2. Apart from a slight increase in the pigmentation of the skin of the anterior abdominal wall and areola of one male guinea-pig, no obvious changes were noted microscopically.
3. Histological investigation showed that the hormone caused an increase in the length, width and complexity of the dendritic processes and that this was accompanied by an increase in the amount of melanin present within the processes. In the skin of the anterior abdominal wall numbers of melanocytes were significantly raised and the amount of free melanin was increased. In many of the animals the amount of melanin present within the cell bodies of the melanocytes was increased in all the skin regions and in some of these this was associated with an increase in size of the cell body.
4. The hormone produced its greatest effect on the melanocytes in males.
Search for other papers by P. G. BISCHITZ in
Google Scholar
PubMed
Search for other papers by R. S. SNELL in
Google Scholar
PubMed
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.
