SEX-CHROMOSOME DETERMINATION IN EXTRAGONADAL TERATOMAS BY INTERPHASE CYTOGENETICS - CLUES TO HISTOGENESIS

Teratomas are neoplasms that are composed of tissues from all three ge rminal layers. The exact histogenetic origin of teratomas, however, is still controversial. In order to gain more insight into histogenesis of extragonadal teratomas (EGTs), the gonosomal status in 13 congenita l EGTs was studied by means of interphase cytogenetics using nonradioa ctive in situ hybridization (NISH) with centromere-specific DNA probes . By use of this technique a direct correlation of cytogenetic results with morphology was possible. In all EGTs analyzed the gonosomal stat us in tissues derived from the different germinal layers was identical to that of the nontumorous fetal and placental tissue. This was true irrespective of localization, age, histological type, and classificati on of the EGT. Our results strongly suggest that EGTs arise from pluri potent diploid precursor cells, for example, either premeiotic germ ce lls that have not yet undergone the first meiotic division or pluripot ent ectopic embryonal or extraembryonal cells. Our data do not support the theory of parthenogenetic EGT development, at least in males.