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

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.