Tomoichi Ishikawa

THE PROCESS OF DIFFERENTIATION OF EMBRYOID BODIES IN THE LUNG OF SYNGENEIC MICE

The process of differentiation of embryoid bodies of mouse teratocarcinoma OTT6050 transplanted into the lung of syngeneic mice (129/Sv) is described. Embryoid bodies took more than 2 weeks to differentiate, and several kinds of differentiated tissues appeared often in the colonies derived from a single embryoid body. All the colonies with differentiated tissues were larger than 100μm in diameter.

GROWTH AND MITOTIC ACTIVITY OF LUNG COLONIES DERIVED FROM MOUSE TERATOCARCINOMAS

This study dealt with the mitotic activity of lung colonies in the process of differentiation of mouse teratocarcinoma cells injected in vivo. The results showed that three stages were identifiable in respect to the mitotic activity: 1) a lag stage for a few days after injection, 2) a stage during which maximum mitotic activity is observed for several days following the first stage and 3) a third stage displaying a decrease in mitotic activity. There is a correspondence between these three steps in mitotic activity and differentiation in lung colonies previously identified by histological observations.

Localization of Mg++-dependent adenosine triphosphatase and alkaline phosphatase activities in the postimplantation mouse embryos in day 5 and 6.

SummaryMg++-dependent adenosine triphosphatase (Mg-ATPase) and alkaline phosphatase (ALPase) activities were histo- and cytochemically investigated in postimplantation mouse embryos from day 5 to day 6. In day 5 postimplantation embryos, Mg-ATPase activity was detected in the embryonic ectoderm and weakly in the visceral endoderm. Weak ALPase activity was found in the embryonic ectoderm and visceral endoderm. Parietal endoderm, both in day 5 and in day 6 embryos, had very weak or no Mg-ATPase and ALPase activities. Mg-ATPase activity in day 6 embryos was found with the same localization as that in day 5 embryos. No ALPase activity was observed in their embryonic ectoderm. Extraembryonic ectodermal cell mass had the strongest Mg-ATPase activity in these stage embryos.These results suggest that the localization of both enzyme activities in postimplantation mouse embryos is closely related to the morphogenesis. As regards the proamniotic cavity formation, the fact that Mg-ATPase activity was still observed in the embryonic ectoderm in these stages suggests the involvement of active transport system on the production of nascent proamniotic cavity fluid.

Conditions Permitting Solid Tumor Formation of Teratocarcinoma Cells in Allogeneic Mice

In this report, the growth capacity of murine ascitic teratocarcinomas (embryoid bodies, EBs) was studied in certain strains of allogeneic mice. When EB was intravenously injected into Balb/c mice, various types of tumor colonies were formed with various types of differentiated tissues in the lung, as in the case of syngeneic 129/Sv mice. Tumor colonies in the abdomen of Balb/c and other allogeneic mice formed by the intraperitoneal injection of EB, however, contained merely undifferentiated embryonal carcinoma cells (EC cells) and sometimes some primitive tissues, too. Analysis of lung colonies (LCs) from EBs in Balb/c mice indicated that EC cells are a potent target for being rejected but they can escape this rejection by differentiating into various types of tissues cells.

Tissue Differentiation in Mouse Teratocarcinomas in Lung Colonies from Ascitic Embryoid Bodies

Tissue differentiation in ascitic teratocarcinoma embryoid bodies (EBs) was investigated in the lung colony system of syngeneic 129/Sv and allogeneic Balb/c mice previously reported by us. In this report, tissues are classified as neural, epithelial and mesodermal tissues. Although multiple differentiation in these three groups of tissues became evident about a month following an injection of EBs, colonies containing only one type of tissue but not mesodermal were commonly found. There were few colonies containing only mesodermal or both neural and mesodermal tissues. This suggests that mesodermal tissue differentiation takes place, as in normal embryogenesis, through the formation of a mesodermal layer, which has not been found in vivo.