Über das Sexchromatin und Sexchromatin-ähnliche Kernstrukturen in menschlichen Purkinjezellen

Abstract

Introduction Animal experiments have shown that in the course of chromatolysis the nuclear sex chromatin of nerve cells of female mammals changes its customary location at the nucleolus and migrates to the nuclear membrane; moreover, in the nuclei of nerve cells of males there occur under similar conditions nuclear structures which resemble the sex chromatin. It was, therefore, thought of interest to see if similar findings also apply to human Purkinje-cells. Material and methods The cerebellum of 100 female and of 52 male corpses of various ages was examined. Paraffin sections, 2–5 μm thick, were stained with haemalum-eosin and, after hydrolysis by hydrochloric acid, with cresyl violet or Schiffs reagent (Feulgen stain). In each cerebellum 100 Purkinje-cells, whose nuclei showed a well developed nucleolus and an obvious Barr body, were studied. In the cerebellum of 29 female corpses the cells examined showed a marked cytoplasmic chromatolysis; in the Purkinjecells of the remaining 71 female, and of all the male corpses the stage of chromatolysis was classified according to the degree of dissolution of the Nissl bodies as “feeble”, “marked”, or as the stage of restitution, characterized by nuclear caps. Results The sex chromatin was seen as a, mainly, round and compact chromocenter with a maximal diameter of 0.6-1.6 μm. The larger Barr bodies were seen more frequently, if chromatolysis in the corresponding cells was marked. With increasing chromatolysis the Barr body, which usually occupies a perinucleolar location, tended to be found more often at or near the nuclear membrane. In the cerebellum of the males 174% of the Purkinje cells studied showed heteropyknotic nuclear structures which could not always be dinstinguished in size or in appearance from a sex chromatin. They occupied predominantly a perinuclear position, but with increasing chromatolysis they too were seen more frequently in a location which tended to be intermediary or near the nuclear membrane. Not infrequently the nuclei simultaneously presented a granular hyperchromatosis. Discussion The change in the location of the sex chromatin in the nucleus is considered to be associated with compensatory processes following chromatolysis. These in turn are accompanied by an intranuclear current of materials, such as RNA, towards the periphery of the nucleus, or by changed electric potentials which develop in the affected cells. The variations in size of the Barr body should be attributed to a variable condensation of the corresponding X-chromosome, rather than to polyploidy of the nerve cell nuclei. The sex chromatin-like chromocenters, which are seen in “male” Purkinje-cells in the course of chromatolysis, could be attributed to certain chromosomal segments which have a tendency to hererochromasia. In this context one would have to consider in the first place an induced heteropyknosis of the one X-chromosome occurring in the male, since this chromocenter shows the same changes in location within the nuclear space as does the sex chromatin of the female. A phaenocopy of the “pseudo-sex chromatin” by autosomal perinucleolar condensations, which develop in the course of a beginning general granular hyperchromatosis, is, however, possible and cannot always be recognised with certainty as such.