Effects of Valproate, Thalidomide and Alcohol on the proliferation of trophoblast. Mean ± standard deviations of the number of HTR cells in culture in the absence and presence of a drug or alcohol. Number of cells between 3 and 12 h of incubations were not significantly different (p > 0.05) in untreated cells (controls). Treatments with low and high concentrations of valproate for 12 h did not alter cell numbers from untreated cells (12 h control) significantly (p > 0.05). Treatments with thalidomide at low concentration and alcohol at both low and high concentrations for 12 h increased number of cells significantly from the controls. Treatment conditions and time of incubations are shown below each bar. * Significantly different from controls at p < 0.05. Symbols Controls (□), Valproate (■), Thalidomide (), Alcohol ().