Ultrastructural Differentiation of an Unusual Structure Lining the Anticlinal Walls of the Inner Secretory Cells in Tamarix Salt Glands

The lateral walls of the inner pair of secretory cells in Tamarix aphylla L. salt glands are bordered by an unusual structure, the interfacial apparatus (IA), which is an extraplasmic structure of two asynchronously formed connected parts. The upper part of the IA initially consists of a complex system of waxy layers; later, many large cytoplasmic vesicles with a lipoidal content appear to empty into this part. The lower part of the IA is smaller than the upper and contains proteinaceous material. The lower part is often found in close association with vesicular profiles or cisternal elements of rough endoplasmic reticulum. The possible functional significance of the IA is discussed.