Intranuclear microfilament bundles in the ependymal cells of the third ventricle of the rat

Summary Intranuclear microfilament bundles were observed in ependymal cells of the third ventricle of the rat. They appeared as single, cylindricallyshaped fibrillar bands up to 4.9 m in length. In cross sections of bundles, the microfilaments exhibited an apparently regular arrangement. They were separated by a distance of 4 to 5 nm, measuring approximately 11 nm from centre to centre. One bundle consisted of 55 to 88 microfilaments. The intranuclear bundles terminated at the inner membrane of the nucleus. They exhibited close spatial relationship to perinuclear chromatin, chromatin centres, intrachromatin granules and fibrillar structures. The average ratio of nuclear sections with and without bundles was 115.Research fellow of the Alexander von Humboldt FoundationThis research was partly carried out at the Department of Histology and Embryology, Academy of Medicine at Poznan, Poland, and was supported in part by a grant from the Polish Academy of Science