Established vessels formed in long-term cultures of normal 8.5-dpc allantoides exhibit incremental disassembly in response to BV13 treatment. (A-D) Confocal images of PECAM-immunolabeled allantois cultures derived from normal 8.5-dpc embryos. (A) A control explant cultured for 30 hours. (B-D) Explants that were first cultured for 18 hours and then cultured for an additional 2 (B), 6 (C), or 12 hours (D) in the presence of BV13 (24 μg IgG/mL). Alterations in vascular morphogenesis are evident at 6 hours after addition of BV13 (C). By 12 hours after BV13 administration, the now 30-hour-old culture (D), as compared to control (A), shows an almost complete dysmorphogenesis of the blood vessels. Bars equal 100 μm.