Cutaneous changes during prolonged application of XXXX on @entity19 skin and residual effects after cessation of treatment.

@entity32 @entity19 @entity4 @entity1373 @entity1185 @entity5 @entity189 @entity665 @entity865 @entity105 @entity864
The epidermal and dermal effects of protracted @entity864 ( @entity865 ) treatment (2 micrograms @entity865 twice weekly) of Sencar @entity19 skin were studied using cell kinetics and morphometric techniques. In addition, regression of @entity865 -induced changes was evaluated after cessation of 56 topical applications. During the first week of treatment a reactional @entity1373 , characterized by cell damage, @entity4 , and acute @entity32 in both epidermis and dermis, occurred. This picture changed gradually during the following 3 weeks: an @entity1373 devoid of involutional or inflammatory features was accompanied by a moderate to mild @entity32 of the dermis and a @entity1373 of the hair follicles. This remained throughout the experimental period until the topical @entity865 treatment ceased. Although @entity865 induced @entity1185 in only 5% of the animals (maximum = 2 @entity1185 /animal and no @entity189 ), all sustained marked @entity1373 of approximately 4 to 5 times the normal thickness, and increased the number and volume of hair follicles. The @entity665 pulse-labeling index of the basal layer was approximately 32% (normal congruent to 6%). The level of dark keratinocytes remained constant; i.e., 8% of the basal cells were identified as dark cells during the entire experiment. At the subepidermal level the dermal thickness and total cellularity increased, although the proportion of the different cell types changed during the treatment. The mast cell population increased remarkably. After @entity865 treatment ceased, most of these parameters regressed abruptly during the first 2 weeks. Two to 4 months later, the epidermis was slightly thinner, and the labeling index was 50% lower than normal (2.8%). This study shows that prolonged repetitive @entity865 applications induced a @entity1373 without tachyphylaxis, and that this alteration regressed rapidly after treatment ceased. In addition, labeling-index values lower than normal were reached soon after normalization, suggesting that a possible selection of keratinocytes, dependent on @entity865 for proliferation, took place during the chronic administration of topical @entity865 . The number of hair follicle, capillary vessels, mast cells, and the dermal thickness never reached normal values after treatment. These important changes in the dermis and hair follicles indicate that the target cells for @entity5 promoters are not confined to the epidermis alone, and that these tissues could participate actively in @entity105 directly, either as @entity5 -originating tissues (hair follicles), or as inducers or helpers of @entity5 (connective tissue cells).
