Japanese Journal of Veterinary Research;Volume 13, Number 3



SUGIMURA, Makoto;FURUHATA, Kitao;OHTAISHI, Noriyuki;KUDO, Norio;MIFUNE, Yoshikatsu

Permalink : http://hdl.handle.net/2115/1827
JaLCDOI : 10.14943/jjvr.13.3.96


Peculiar nuclear inclusions, "nucleoloid bodies", were found in nuclei of several types of cells in mouse lymph nodes and in sheep hemal nodes. The nucleoloid bodies were morphologically independent of the nucleolus and the chromatin. They were spherical in shape, ranging from 200 to 900mμ in size, with outer and inner layers that could be differentiated. The outer layer consisted of numerous filaments arranged concentrically or spirally which encircle completely the inner layer. The filaments were helical coils, measuring 70〜80 Å in width. The diameter of the fibril coiled into the helix was approximately 20〜30 Å. The same helical fibrils were also found in the chromatins of nucleoplasm around the nucleoloid bodies. The inner layer was composed of a homogeneous substance of lower electron density and of a variable number of dense granules which were similar to ribosomes in appearance. At high magnification, however, the granules seemed to be twisted threads in which thinner fibrils were coiled. The threads were 200〜250 Å in width and the helical fibrils measured about 50 Å in diameter. The nucleoloid bodies were separated into two types. The first type was small, about 200〜300 mμ in size, and had no or a few dense granular elements in the inner layer. The second type was larger, over 400 mμ in size, whose inner layer had numerous granular elements. The nucleoloid bodies were most often observed in small lymphocytes, in particular the large bodies (second type) were almost limited to the small lymphocytes, though rarely in plasma cells as well. Even if nucleoloid bodies were found in cells other than small lymphocytes, it was rare finding and usually involved the small bodies (first type) only. The nucleoloid bodies seemed to derive from the true nucleoli and were observed in the chromosomes throughout mitosis. From the ultrastructure of the nucleoloid bodies, it was suggested that the bodies consist of a specialized nuclear protein unlike the chromosomes.