Peripheral Position of Sex Chromatin

Abstract

IN examining buccal smears for sex chromatin, one finds a surprisingly high incidence of sex chromatin bodies not merely at the nuclear membrane but also more precisely at the periphery of what appears to be a disk-shaped nucleus. The following discussion will provide evidence that, as in tissue cultures¹, the sex chromatin is characteristically at the edge of the nuclear disk in squamous cells in vivo. In establishing this let us first consider that squamous nuclei in vivo are flattened. This may be seen in mucosal smears when a mucosal fragment is folded over (Fig. 1). It is evident, too, that the cells in fragments in the smear maintain the same relative position to one another that they had in vivo, and that one is seeing the cells as one would have seen them in looking directly down on to the mucosal surface. Further, in most nuclei which can be reliably scored, one can visualize all, or almost all, the nucleoplasm by focusing up and down. Thus one can visualize the sex chromatin regardless of its position in the nucleus.