DIFFERENT IMMUNOREACTIVITIES OF ANTI-SOLUBLE LACTOSE LECTIN ANTISERA TO TISSUES FROM EARLY CHICK-EMBRYOS - A HISTOCHEMICAL-STUDY

The location of soluble lactose-binding proteins (S-lac lectins) has b een studied by immunohistochemical methods during morphogenesis of the chick embryo, when segregation and early differentiation of organ pri mordia was occurring. Using a panel of polyclonal antisera raised to v arious purified lectin preparations, we observed striking differences in the antigenic properties of these antisera, indicating that diverse versions of the lectins may be expressed during development. The anti sera referred to as anti-L-16, anti-M-16, anti-S-14 and anti-I-14 were respectively raised to native or denatured 16 kDa lectins from adult liver and embryonic muscle and to 14 kDa lectins from embryonic skin a nd adult intestine. Having determined the optimal immunohistochemical conditions in the preparation of embryo sections (fixation, embedding, sectioning) we show that anti-L-16, anti-S-l4 and anti-I-14 mostly bi nd the lectins expressed at the cell surface, in the extracellular mat rix and in some released secretion. As previously shown, anti-L-16 and anti-S-14 are also able to recognize the cytoplasmic form of some mig rative lectin-rich cells (primitive streak, neural crest cells, germ c ells). Anti-M-16 was bound exclusively to the cytoplasmic form of the 16 kDa lectin in the same cell lines as above and also in some others, such as in the notochord, the myotomal part of the somites, the phary ngeal endoderm and the cardiac muscle. These different antigenic prope rties may be applied to the accurate mapping of various lectin isoform s and evaluation of the respective contribution of their intra- and ex tracellular variants during development and differentiation.