Morphological differentiation and proliferation of HDSC and THESC in the absence or presence of cAMP or E2P4. Cultivation, in vitro decidualization and proliferation assays of HDSC and THESC were performed as described above. A) Morphological characteristics of untreated and cAMP or E2P4-stimulated HDSC and THESC at day 6 of in vitro differentiation. Representative pictures at a 100-fold magnification are shown. B) Proliferation of HDSC and THESC in the absence or presence of cAMP or E2P4. Cumulative cell numbers of each cultures system (n = 4) were measured in duplicates at 1, 3, 6, 9, and 12 days of in vitro decidualization. * indicates p < 0.05 compared to negative control (n.c.) of the same day; # indicates p < 0.05 compared to n.c. of day 0; n.s., not significant compared to n.c. of the same day.