Thelebolus Microsporus Research Articles

Asci of the Pezizales. IV. The Apical Apparatus of Thelebolus

Light- and electron-microscopic examinations were performed on the ascal walls of Thelebolus microsporus, T. crustaceus, T. polysporus, and T. stercoreus with special emphasis on the development, cytochemistry, and morphology of the apical apparatus formed in each species. In all species the ascus differs in size, shape, and number of ascospores, but the apical apparatus is notably similar. Wall structure most closely resembles that of the bitunicate ascus. Using Congo red and acid fuchsin for light microscopy and silver methenamine for electron microscopy, we observed that the ascal wall in T. polysporus and T. stercoreus has two layers, each with two strata. The inner layer of the wall in all species consists of microfibrils in a banded pattern. Major development of the apical apparatuses occurs during early ascosporogenesis, differing from that in operculate representatives. Ascal dehiscence occurs in a modified jack-in-the-box manner. Thelebolus does not belong in the Pezizales.