Localization of type I human skin collagenase in developing embryonic and fetal skin.

Type I human skin collagenase (HSC-1) was localized in developing embryonic and fetal skin ranging from 6 to 20 weeks estimated gestational age using an antigen-specific, affinity-purified, polyclonal antiserum to HSC-1 and an avidin-biotin alkaline phosphatase procedure. Double immunolabeling with monoclonal antibodies for Factor VIII-related antigen, type IV collagen, and the 68-kilodalton neurofilament subunit was performed using a direct peroxidase procedure. By 8 weeks estimated gestational age, HSC-1 localized to the periderm, the basal cell epidermal keratinocytes, dermal fibroblasts, and surrounding extracellular matrix. At 12 weeks estimated gestational age, HSC-1 immunolabeling showed a continued association with the epidermis and dermis. Dermal and subcutaneous blood vessels and the surrounding extracellular matrix were positive for HSC-1 labeling. HSC-1 staining was also found around developing nerves and in association with dermal fibroblasts. In the developing hair follicle, HSC-1 was present in keratinocytes of the pre-germ, germ, hair peg, and bulbous hair peg. HSC-1 immunoreactivity was also found in association with the hair canal, the bulge, and the dermal papillae, but was absent from the fetal sebaceous gland. These data demonstrate the association of HSC-1 with the development of interfollicular epidermis, the dermal collagenous matrix, the process of angiogenesis, the development of nerves, and hair follicle morphogenesis.