[Scanning electron microscope study of the lung epithelium of the rabbit during ontogenesis].

The development of the bronchial and alveolar epithelium was observed in rabbits from the 15th day post conception until the time of birth with the scanning electron microscope. In the pseudoglandular phase, primitive bronchi proliferate in the mesenchyme. The epithelial cells are not differentiated and have single cilia.

The differentiation of isolated amphibian ectoderm with or without treatment with an inductor : A scanning electron microscop study.

Amphibian gastrula ectoderm was isolated and examined by scanning electron microscopy after 24 h, 48 h, 6 and 10 days in culture.Contrary to the view which was formerly held, ectoderm is already detemined to form epidermis at the early gastrula stage. The ultrastructural differentiation of the epidermal cellsin vitro is very similar to their developmentin vivo (Billettet al.