Fig. 6. Bmp7 induces mesenchymal aggregation and proliferation. Mesenchyme from E15.5 lacrimal glands was isolated and cultured for 48 hours in either defined medium (A,D,F,H) or with 100 ng/ml Bmp7 (B,E,G,I). (A,B) Cultures labeled with the nuclear dye Oligreen. Bmp7 treatment results in a striking aggregation of the cells (B). (C) Treatment of lacrimal gland mesenchyme with Bmp7 for 24 hours results in a dose-dependent increase in proliferation as indicated by the increased number of BrdU-labeled cells. Mesenchyme cultures were immunolabeled for connexin 43 (D,E), cadherins (F,G) or -smooth muscle actin (H,I). (D-G) Immunoreactivity is shown in green, while nuclei are counterstained blue with Hoechst. (H,I) Immunoreactivity is shown in red, the nuclei in green. In all three cases, an increase in immunoreactivity was observed in Bmp7-treated cultures and associated with aggregated cells. (J,K) Confocal images of whole, wild-type, explanted lacrimal glands labeled for SMA (red) and Pax6 (green) after growth in the absence (J) or presence (K) of 100 ng/ml Bmp7. Bmp7 increased the level of expression of SMA.