Fine Structure of Pilobolus: Surface and Wall Structure

SUMMARYThe surface and wall structure of two species of Pilobolus was studied with both scanning and transmission electron microscopy. The surface of the sporangium is covered with crystals of two distinct sizes. The larger crystals enclose spines having a central pore. Similar spines occur on both the subsporangial swelling and the stipe; however no crystals are present on these. In all cases the spines arise from the wall surface and have no connection with the interior of the fruit body. “Water droplets,” present on living fruit bodies of Pilobolus spp., persist following freeze-drying for scanning electron microscopy. The sporangial wall consists of three layers whereas that of the subsporangial swelling and stipe is bilaminar.