Nuclear membranes and inclusions in overwintering sporogenous cells of Scotch pine

摘要

The sporogenous nuclei of the Scotch pine (Pinus sylvestris L.) produce membraneous structures, the type and the number of which vary during the course of the yearly cycle. The nuclear membranes develop both evaginations and invaginations. Part of the structures seen inside the nuclei seem to originate separate from the nuclear membranes. The intranuclear vesicles and vacuoles are either multimembraneous or surrounded by a single or a double membrane. Some nuclei contain small crystals. Fibrous areas, supposedly representing extrachromatin matrix, occur frequently in nuclei staying at prolonged interphases.