Immunohistological studies on the reconstitution of nephric tubules from dissociated cells.

SINCE Moscona & Moscona (1952) and Townes & Holtfreter (1955) demonstrated the phenomena of sorting-out and selective localization of cells into a compound (heterotypic) reaggregate, several workers have taken a growing interest in the mechanism of these processes (e.g. Curtis, 1960, 1962; Steinberg, 1962a, 19626, 1962c, 1963). In approaching this subject experimentally, a basic requirement is that the cells derived from different sources possess markers which can be followed throughout the culture period, since it is impossible to discuss the relative movement and displacement of cells which do not possess any marking. Thus xenoplastic combinations of mouse and chick cells or the use of radioisotopes have been adopted to mark the cells (Moscona, 1957; Trinkhaus & Gross, 1961; Zwilling, 1963). However, even such apparently ingenious conti ivances are not perfect solutions, since the organs used, e.g. liver, kidney, limbbud etc., are complexes of various kinds of tissue and it does not follow that these labels mark the cells derived from a single tissue type. To eliminate this defect, the potential usefulness of pigment cells in heterotypic combination has been investigated recently (Trinkhaus, 1963; Trinkhaus & Lantz, 1964), but this limits the variety of heterotypic combinations which can be examined. The author has been interested in the possibility of using 'tissue-specific' antigen(s) of the cells belonging to a particular tissue type as marker(s) at the tissue level, and possibly at the organ level. Recently considerable advances have been made in the study of the antigenic constituents of tissue cells, and it has become possible to extract' kidney-specific' antigens in a semi-purified form from the microsomal fraction of adult chicken kidneys (Okada & Sato, 1963a, 19636). In fact, the antisera prepared against this extract (K45) is highly' kidney-specific', and can be utilized in immunohistological procedures as a potent analytical