Metamorphic changes of dermis in skin of frog larvae exposed to thyroxine

Abstract

Larvae of Rana pipiens immersed in a strong thyroxine solution at Taylor-Kollros stages VI-VIII survived up to 7-8 days. Samples of head skin were fixed daily and prepared for electron microscopy.Protoplasmic processes from mesenchyme cells protrude into the basement lamella in control animals not exposed to thyroxine and in those exposed but 1 day. Channels containing ground substance and fine filaments are oriented vertically in the lamella.By 2 days after immersion cell bodies of mesenchyme cells have moved into the basement lamella. Mesenchyme cells are found closer to the epidermis after 3-4 days.By days 5-7 mesenchyme cells have moved outward to form the stratum spongiosum separating basement lamella from epidermis.