Cell renewal in noncornified and cornified buccal epithelium in the rabbit.

This study was undertaken to compare some aspects of cell renewal in the noncornified and cornified epithelia that are juxtaposed in the buccal mucosa of the rabbit. Specimens were analyzed by autoradiography and scintillation counting at various times after the injection of tritiated thymidine or triated proline. In the noncornified epithelium, the labeling index in the proliferative compartment at 1 hr was 15.

Cleft palate induction: quantitative studies of 3H corticoids in A/Jax mouse tissues after maternal injections of 3H cortisol.

A/Jax mice were injected with 50 muCi of 3H cortisol and 10 mg of cortisone acetate on day 12 of gestation. At various intervals after injection, the maternal liver, placenta, yolk sac, and the fetal jaws were removed and analyzed by thin-layer chromatography in conjunction with oxidative combustion and liquid scintillation counting to identify and measure the amount of labeled corticoid metabolites. The results support the thesis that these corticoids may induce clefts by an individual or combined direct action on the fetal jaws and palatal shelf tissue.

Microscopic tracing of deuterium.

The development of the ion microprobe analyser has made it possible to follow stable isotopes with microscopic resolution in biological and other materials. An ion microprobe using an oxygen primary beam has been found to produce relatively few mass 2 ions (+ or -) on organic samples. This technique should permit the use of deuterium as a practical tracer with a resolution of about 1 mum in the plane of the section and 2 nm in the depth dimension with available instruments.