An implant labeling technique employing sable hair probes as carriers for 3H-thymidine: applications to the study of facial morphogenesis.

An implant labeling technique is described that utilizes sable hair probes as carriers for a tritiated thymidine marker. The protocol that was developed produced localized labeling of specific embryonic cell populations. This procedure was applied to the analysis of facial process development in chick embryos. Evaluation of the technique demonstrated that the probe preparation procedure was consistently successful in producing labeled probes. Using labeled probes, the procedure was reliable in producing acceptable levels of labeling in chick embryonic tissues and labeling of localized cell populations was possible using the implant labeling technique. Surrounding the center of labeling, a gradient in intensity of labeling was often observed. This pattern presumably reflects declining availability of labeled thymidine as distance from the probe increased. The technique allowed excellent survival rates to be achieved provided that aseptic procedures were followed. Additionally, careful analysis of older embryos failed to reveal any malformations induced by the implant labeling procedure. The localized labeling patterns that were demonstrated during this investigation suggest that the implant labeling technique would provide a useful tool for following cell migration during facial process formation.