The permeability of whole human skin, human dermis, whole pig skin, and canine buccal mucosa have been determined for four chemically different solutes: tritiated water, amphetamine, estradiol, and ouabain. Several new in vitro techniques for isolation, preservation, and permeability determination of these membranous tissues are described. Water permeabilities of human epidermis and dermis using these techniques agree well with published results. Human and porcine skins are very similar with respect to water permeability, while buccal mucosa is similar to dermis in its permeability characteristics to the four representative test agents. The permeability of hydrated whole skin is determined by the permeability of the epidermis, and the dermis and buccal mucosa behave as if they are water barriers exhibiting a permeability of about 30% of the diffusion through pure water, a difference that can be ascribed to the porosity and/or tortuosity of the tissue matrix.

The McLeod phenotype is inherited as an X-linked characteristic. The red cells have weak antigenicity in the Kell blood group and lack Kx, a precursor-like substance that appears to be necessary for proper biosynthesis of Kell antigens. Kx antigen is also required for establishment of normal cell morphology. Absence of Kx antigen causes a membrane abnormality, in which the most prominent feature is acanthocytosis, and a compensated haemolytic state. The X-linked gene that determines normal Kx production is called X1k. Inheritance of a variant allele at the Xk locus is responsible for lack of Kx synthesis and the McLeod phenotype. The Xk locus is inactivated by the Lyon effect, and female carriers of the variant gene exhibit blood group mosaicism in the Kell system and have a dual red cell population of acanthocytes and discocytes.