Helical extrusions at the nuclear envelope: possible involvement in nucleocytoplasmic trafficking

The existence of intracytoplasmic helical inclusion 24 h after serum stimulation of 3T3 cells which had previously been serum deprived (0. 2%) for 2 days has been previously reported. Further evidence of their relationship with nuclear pores has been found, and their involvement in nucleocytoplasmic transport seems more probable. Helical formations resembling those originally seen have been found seemingly extruding from nuclear pores into the cytoplasm. However, it is unlikely that these structures contribute significantly to the translocation of material from the nucleus to the cytoplasm on a regular basis because their occurrence is rare. An association of the helical complexes with microfilaments has also been observed. Their relationship to annulate lamellae remain enigmatic.