Selective lectin-binding sites of primordial germ cells in chick and quail embryos

To ascertain the histochemical characteristics of surface carbohydrates on avian primordial germ cells (PGC), we examined the distribution of binding sites for several biotinylated lectins in chick and quail embryos. Some binding sites were detected almost selectively with PGC but not with other embryonic sites. Of these, lectin from Sojanum tuberosum (STA) reacted with PGC in both avian species, whereas lectin from Wistaria floribunda (WFA) and Griffonia simplicifolia II (GS-II) reacted in the quail and the chick, respectively. The binding site for STA was found at the cell surface and cytoplasm of the PGC from their initial appearance in the germinal crescent through migration to sexually indifferent gonads, whereas the WFA reaction was seen at stages before and during migration. These reactivities showed most intensely on the surface of PGC at the peak of their migration. In contrast, GS-II binding site was restricted to the cytoplasm, and its distribution was similar to that of the periodic acid-Schiff (PAS)-positive glycogen granules in chick PGC. These results suggest that some selective binding sites on the PGC surface play a significant role in their migration and show that lectins STA, WFA, and GS-II can be used as probes for identification of the avian PGC.