Response of severed Penicillium chrysogenum hyphae following rapid Woronin body plugging of septal pores

Colonies of Penicillium chrysogenum (Thom) Wisconsin strain Q176 were fixed at varying time intervals after having been severed with a razor blade and were examined by transmission electron microscopy. Within such colonies Woronin bodies were found to have plugged septal pores on either side of the cut, both towards and away from the hyphal apices. A very close association of Woronin bodies with septa was retained in damaged compartments emptied of virtually all other contents. In colonies fixed 3 h after cutting, deposition of material over the plugged pores occurred on the side of the septum away from the cut. The newly deposited material was similar in appearance to hyphal wall and septal plate constituents. This consolidation of the seal was apparently completed within 3 h because no further change was observed in colonies fixed 17 h after cutting.