ISOLATION AND MAINTENANCE OF THE HUMAN PILOSEBACEOUS DUCT - 13-CIS RETINOIC ACID ACTS DIRECTLY ON THE DUCT INVITRO

The human pilosebaceous duct was isolated and maintained for 7 days in defined medium, and defined medium supplemented with 1 muM 13-cis retinoic acid. Freshly isolated ducts retained their in vivo morphology, showing a stratified squamous keratinizing epithelium. On maintenance there was a loss of basic duct architecture, and a significant reduction in the rate of [methyl-H-3] thymidine uptake. The addition of 1 muM 13-cis retinoic acid resulted in an improved duct architecture and caused a further significant reduction in the rate of [methyl-H-3] thymidine uptake. [Methyl-H-3] thymidine autoradiography showed that freshly isolated ducts maintained their in situ pattern of cell division. It was difficult to discern the region of cell division in ducts maintained for 7 days, but the degree of graining reflected the measured rates of [methyl-H-3] thymidine uptake into PCA precipitable material. The pattern of keratin synthesis of the freshly isolated duct was similar to patterns previously described for the duct in situ. This study reports the successful isolation and maintenance of the human pilosebaceous duct, and demonstrates that 13-cis retinoic acid acts directly at the level of the duct.