Cell surface changes during adipocyte differentiation in vitro.

Not least among the notably important advances in knowledge concerning the origin and development of white adipose tissue has been the recognition of the adipocyte precursor and the demonstration that such cells can be isolated from mature tissue and be induced to differentiate to adipocytes in vitro. The interest generated in the nature, origin, proliferation and differentiation of the adipocyte precursor has lead to studies on cells of human (Van et al., 1976), rat (Bj6rntorp et al., 1978 ; Roncari et al., 1979), mouse (Négrel et al., 1978), bovine (Plaas and Cryer, 1980 ; Cryer et al., 1984), ovine (Broad and Ham, 1983) and avian origins (Cryer J. and Cryer A., unpublished observations). Additionally the 3T3-H mouse embryo fibroblast clone and other related clones have also been used extensively as a model of adipocyte differentiation in vitro (see for example Green, 1979 ; and Ailhaud, 1982, for review). The patterns of enzymatic differentiation displayed by precursor cells isolated from mature and from embryonic sources are now well characterized and are compatible with the adipocyte nature of the cells following their differentiation in culture (Green, 1979 ; Cryer, 1980, 1982). Although certain information has become available (Sidhu, 1979 ; Reed et al., 1980 ; Plaas et al., 1981) with regard to the 3T3-L i cell clone, relatively little is known of the cell surface changes that characterize adipocyte differentiation in precursors of mature tissue origins (Cryer et al., 19841. Because immunological assay methods have proved so useful in the study of cell surfaces in many other differentiating cell systems (Williams et al., 1977 ; Trisler et al., 1979) the possibilities for the use of an immunologically-based technique for studying adipocyte differentiation have been pursued.