Detailed information about this set of experiments can be found in the following publication:

Mazzalupo S, COULOMBE PA (2001). A Reporter Transgene Based on a Human Keratin 6 Gene Promoter Is Specifically Expressed in the Periderm of Mouse Embryos. Mechanisms of Development 100: 65-69.

We investigated the developmental regulation of a lacZ reporter transgene fused to the promoter region of the human keratin 6a gene. In mouse embryos, the transgene is expressed in the periderm (the outermost layer of embryonic epidermis), as are the endogenous keratin 6 a and b genes. A subset of periderm cells, localized to temporary epithelial fusions, is known to contain keratin 6 protein, and we find that these cells also harbor LacZ enzymatic activity.