The purpose of this study is to investigate the relation between the fine structure of the
tumor cell surface and the
tumor malignancy by scanning electron microscopy. Practically, comparison was made between the invasive Ehrlich
ascites clone 1
tumor and the non-invasive Ehrlich
ascites clone 3
tumor, and also between the 4th postinoculation day and the 6th postinoculation day as regards the growth of microvilli on the cell surface. On the 4th postinoculation day, an invasive clone 1
tumor cell was indistinguishable from a non-invasive clone
tumor cell because of their common paucity of microvilli development. On the 6th postinoculation day, the former was associated with exuberant growth of microvilli, and was clearly distinguished from the latter in which the density of microvilli stayed low as before. The appearance of dense microvilli growth in the invasive clone 1
tumor cells chronologically coincided with the stage of fatal
bleeding into the abdominal cavity.
Hydrocortisone with a dose of 1 mg/mouse, when given subcutaneously to a
tumor-bearing mouse on the 4th postinoculation day, stimulated the development of microvilli in both clone 1 and clone 3
tumors. The enhancing effect of the
hormone on this process was detectable 2 hours after
hormone injection. It was indicated that the dense growth of microvilli in the clone 1
tumor facilitated its
tumor invasion into visceral organs, and that the enhancing effect of
hydrocortisone on microvilli development was to be related to the promotion of malignant transformation. The possible implications of
glucocorticoid in mammocarcinogenesis are discussed from the point of view of comparative endocrinology.