[Cytogenetic studies of multiple ovarian dermoid cysts in a single host].

To investigate the pathogenesis of gonadal teratoma, sixteen ovarian dermoid cysts obtained from four patients were examined by using chromosomal Q and R heteromorphisms, HLA antigens and enzyme polymorphisms of phosphoglucomutase-1 and esterase-D. The results obtained were as follows: 1) Karyotypes of 16 tumors were 46,XX. 2) In thirteen tumors, chromosomal heteromorphisms were homozygous for the homologous chromosomes, being heterozygous in the hosts. In 9 of them, all gene markers analyzed were also homozygous, but in the remaining 4 tumors some gene markers showed heterozygous combination. These findings indicate that these 13 tumors arose from a germ cell after the first meiotic division by suppression of the second meiotic division or by fusion of polar body II with the oocyte. 3) In three tumors, chromosomal heteromorphisms showed heterozygous patterns as in the hosts. In 2 of them, some gene markers were homozygous, and in the remaining one tumor the gene markers were all heterozygous. These findings suggest that these three tumors arose from a germ cell before the first meiotic division. It is concluded that multiple ovarian dermoid cysts in a single host originate from different germ cells with diverse mechanisms.