A non‐invasive photographic modification for recording early vascular development in the chick

Summary The chick embryo shell‐less culture technique allows continuous observation and access to the developing vessels of the area vasculosa (AV): hence, its value as an angiogenesis assay system. The main drawback of the method is that adequately contrasted photographs cannot be achieved without injection of a contrast medium which kills the embryo making further observation of the same specimen impossible. Furthermore, injection prior to 72 h incubation has a high failure rate. In an attempt to overcome these problems, we explored the possibility of using a high‐contrast photographic process. Embryos were explanted into shell‐less culture after 48 h incubation and photographed through a stereo microscope. After trials with different films we found that Kodalith ortho Type 3 (Kodak) and Technical Pan film (Kodak) produced images of the vasculature which were identical in contrast and detail to India‐ink‐injected specimens photographed with conventional film. In addition, excellent images could be recorded as early as 48 h of incubation.