Oocytes of four species of ascidians were examined with the electron microscope. Prior to fixation, oocytes were subjected to centrifugal forces of 10–15,000 g for 5–10 min and were compared with uncentrifuged oocytes. Intranuclear annulate lamellae (IAL) are distributed uniformly around the periphery of the nucleus of the uncentrifuged oocyte. Centrifugation produces a marked flattening of the oocyte nucleus, migration of nucleoli to the centrifugal end, and often a condensation of the nucleoplasm at the centrifugal end. In contrast, the distribution of IAL is unchanged by centrifugation. Furthermore, numerous IAL profiles appear to be touching the nuclear envelope, and, in a few of these, direct continuity of the IAL with the nuclear envelope is demonstrated.
Article| May 01 1968
ATTACHMENT OF INTRANUCLEAR ANNULATE LAMELLAE TO THE NUCLEAR ENVELOPE
John W. Everingham
From the Department of Biological Structure, University of Washington, Seattle and the Department of Anatomy, Northwestern University Medical and Dental Schools, Chicago.
Dr. Everingham's present address is the Department of Anatomy, Northwestern University Medical and Dental Schools, Chicago, Illinois 60611
Received: November 28 1967
Online ISSN: 1540-8140
Print ISSN: 0021-9525
John W. Everingham; ATTACHMENT OF INTRANUCLEAR ANNULATE LAMELLAE TO THE NUCLEAR ENVELOPE . J Cell Biol 1 May 1968; 37 (2): 540–550. doi: https://doi.org/10.1083/jcb.37.2.540
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