196 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS at the level of the outermost layers of the viable epidermis also (2). For AZAP, Relier and Luedders have presented some evidence that sweat glands which had been treated with an aluminum-zirconium antiperspirant solution showed masses located mainly in the distal segment of the epidermal sweat duct. These masses appeared to be located more superficially than those seen in sweat ducts which had been treated with aluminum chloride (3,4). ACH is one of the more commonly used active ingredients in today's antiperspirant products. However, the use of AZAP is becoming increasingly widespread and is more effective than ACH in controlling axillary sweating (3,5). The studies reported here were designed not only to complement those previously reported for ACH, but also to establish with certainty the presumed superficial site of the AZAP plug in the eccrine sweat duct. It was further hoped that an understanding would be gained, at least from a morphological standpoint, of why AZAP's duration of antiperspirant activity is longer than that of ACH even though its site of action is more superficial. II. MATERIALS AND METHODS The procedures used to obtain, prepare, and study human forearm tissue containing eccrine sweat glands which had been inhibited by AZAP were identical to those described previously for the ACH study (2). In brief, forearm sites of male subjects were occlusively patched overnight (16-18 hr) with 10% aqueous AZAP (Wickhen Prods., Inc., Huguenot, NY) or distilled water. The sites were then reidentified after thermal stress and full thickness biopsies were taken. For the sites treated with AZAP, only areas exhibiting complete inhibition of sweating were biopsied. For the control sites, areas demonstrating actively sweating glands were biopsied. The tissues were then prepared and studied by transmission electron microscopy and fluorescence microscopy. iii. RESULTS A. OBSERVATIONS MADE USING FLUORESCENCE MICROSCOPY As had been found for ACH-treated sweat glands, cellophane tape-stripping studies demonstrated that the primary site of action in glands which were inhibited by AZAP treatment was also quite close to the skin surface (1). Microscopy studies then confirmed that location of ACH. Parallel studies are now presented which describe the site of action of AZAP within the inhibited sweat glands. Figures la-le are serial sections, made perpendicular to the skin surface, through the same sweat gland. For this gland, which was one of twelve studied, the duct spiraling through the stratum corneum in coiled bedspring fashion was readily discernible. The green fluorescence, which indicates the presence of aluminum and zirconium, was seen sealing off the sweat gland ostium and was present in substantial amounts in the intracorneal duct. In those instances where the duct appeared empty, it is believed that the gaps were a result of artifact due to tissue sectioning or washout of the material. In this particular representation, the aluminum and zirconium were also present in the more distal region, perhaps not deeper than the stratum granulosum, of the intraepi- dermal duct (e.g. Figure lb). This finding was not atypical, occurring in half the glands

ANTIPERSPIRANT ACTION OF ALUMINUM SALTS 197 AZ sc E t I 30 .um Figure la. Figures la-le are serial sections through an AZAP-treated eccrine sweat gland depicting aluminum and zirconium fluorescence in the duct at the levels of the stratum corneum and distal viable epidermis (SC: stratum corneum E: viable epidermis AZ: aluminum and zirconium fluorescence).