Hi, I am culturing intestinal stem cells. As per standard technique I preheat plates, keep matrigel on ice and invert plate in incubator for 30mins to polymerise prior to media addition. I am finding intermittently that domes fail to polymerise and merge into 1 in the well. This occurs after about 20mins, and doesn't happen immediately after plate inversion. It doesn't appear to be matrigel batch issue as other aliquots from the same batch polymerise well. I suspect issue may relate to insufficient aspiration of supernatant but any ideas/ further thoughts greatly appreciated? Thanks