ABSTRACT
This chapter provides examples of recent work on structural and functional differentiation in normal cell spheroids. This is followed by the description of a type of normal cell spheroid derived from embryonal carcinoma cells. The chapter discusses the tumor heterogeneity and differentiation. It presents the differences in differentiation between monolayer and spheroid cultures of tumor cell lines and modulation of differentiation by humoral and stromal components in vitro. Comparisons are made with findings in cultures of primary tumor material in vitro and in vivo xenograft tumors in nude mice. Research with normal embryonic cells and postnatal cells has confirmed the finding of conservation of morphogenic capacities in the three-dimensional in vitro cultures. A useful link between research with spheroids of normal cells and research with tumor-like spheroids is provided by embryonal carcinoma, which is of high interest and value for both developmental biology and cancer research.
