Fig. 1.
In vitro transformation of chick blastoderm cells by E26 and AEV leukemia viruses.
(A) Stage 10 blastoderm (embryo with 10 somites) stained with acid benzidine. Blood islands are dark brown. Original magnification, × 2.5. (B) Colonies obtained 4 days after plating blastoderm suspensions in methylcellulose, stained with neutral benzidine and counterstained with May-Grünwald-Giemsa. Mature, hemoglobin-positive cells are dark brown; blastlike cells are light blue and purple. Left to right panels indicate control, E26-, and AEV-transformed cells, respectively. Original magnification, × 100. (C) Quantitation of colony formation of yolk sac and embryo pools, with and without infection by E26 and AEV leukemia viruses. Mock-infected normal colonies were scored after 4 days of incubation, E26-transformed colonies after 10 days, and AEV-transformed colonies after 6 days. Error bars represent values obtained from duplicate cultures.