Development of kidney-specific antigens: an immunohistological study.

IN principle, it can be stated that initiation of histogenesis is preceded or accompanied by synthesis of molecular species, specific for cells belonging to a particular type of tissue. It has long been suggested that such molecular species, if present, must display immunological tissue-specificity, and an immunological approach to describe tissue-differentiation in embryogenesis at the molecular level is also not new (recent reviews by Tyler, 1955; Edds, 1958; Ebert, 1959; Flickinger, 1962). In fact, a number of important contributions have been made along this line, especially on the development of the antigenic constituents of muscle (e.g. Ebert, 1953; Ebert et al, 1955; Holtzer et al, 1957; Holtzer, 1961) and lens (recent works by Flickinger & Stone, 1960; Maisel & Langman, 1961 Takata et al, 1964). As for other tissue cells, however, our knowledge is still scanty, largely owing to the difficulty of characterizing and isolating tissuespecific antigens, even from differentiated adult tissues. Recently, it has become possible to extract 'kidney-specific' antigens in a semipurified form from the microsomes of adult chicken (Okada, 1962; Okada & Sato, 1963a) and in the author's earlier contribution, some preliminary immunodiffusion studies on the distribution of these antigens in the chick embryos at later stages of development were reported (Okada & Sato, 19636; also Okada & Yamamura on embryonic liver, 1964). In this paper the chronology of appearance of these antigens in the earlier development of mesonephros is studied by the fluorescent antibody technique, which the author had expected to be more sensitive and to permit detailed observations on the developing tissues (e.g. Clayton, 1960). MATERIAL AND METHODS