We studied microsporangium wall structure in Trollius ledebourii Reischenb. The mature microsporangium has a 3 layer wall. Differentiation of its layers occurs centripetally, its correlation with periods of sporogenous tissue development was established. We first detected intermediate type of cells developing between meiocytes and tapetum during abnormal microsporogenesis. Dependence of pollen grains development abnormalities on tapetum and endothecium structure changes was revealed.Key words: microsporangium, microspores, pollen sac wall, epidermis, endothecium, middle layer, tapetum, fibrous thickenings.