Chromosomes of Testicular Teratomas

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Abstract
Eight testicular teratomas arising in proven males were examined for nuclear sex chromatin. Nuclear DNA content was measured in seven of the tumors and attempts were made to study the karyotype in seven and the chromosome late-replication pattern in five. Sex-chromatin-positive stromal, endothelial and epithelial cells possessing near-diploid or near-triploid DNA values were present in five of the eight tumors. Aneuploid DNA values of chromatin-negative regions corresponded with the aneuploid karyotype found in six tumors. The modal chromosome numbers ranged from 53 to 111 Not only was there marked karyotypic instability within each tumor but there was no overall similarity between different tumors. The terminal sequence of chromosome replication, successfully studied in two cases, one of which possessed sex-chromatin-positive cells, failed to reveal a late-replicating X-chromosome. Unfortunately, it was impossible to prove that the chromatin-positive teratoma did not contain a second X-chromosome: the failure to demonstrate an unequivocal XX sex chromosome constitution might be connected with special cultural requirements of the sex-chromatin-positive cells. However, other varieties of embryonic and undifferentiated cell tumors in males have been reported to display nuclear sex chromatin, and even certain normal testicular elements are sex-chromatin-positive. It is concluded that the existence of sex-chromatin-positive teratomas in males does not necessarily imply production from haploid gametes. The present observations do not rule out gametal origin. However, they provide more support for the idea that teratomas arise from diploid cells, possibly misplaced blastomere or primordial germ cells.