ELECTRON MICROSCOPIC STUDIES ON HISTOGENESIS OF TESTICULAR TUMORS

3. Fine Structure of Human Testicular Germ Cell Tumors

Abstract

Thirty cases of human testicular germ cell tumors, including 14 seminomas, one spermatocytic seminoma, 4 embryonal carcinomas and 11 yolk sac tumors, are studied by TEM for the ultrastructural features and histogenesis of each tumor.
The nucleoli of the tumors were generally well developed with dispersed nucleolonema and pars amorpha. The nuclei of seminomatous tumors were round to ovoid in shape with smooth contour, having homogeneously dispersed chromatin, whereas the nuclei of non-seminomatous tumors were polygonal in shape with irregular contour and even segmental in embryonal carcinoma. Two cases of seminomatous tumors seemed to be “anaplastic” from the fine structure of their nuclei.
Basement membrane like material was seen around the tumor cells in half cases of seminomatous tumors and moreover, such structures were prevailing in yolk sac tumors.
Intratubular atypical germ cells were seen light microscopically in 6 cases and three cases were available for ultrastructural examination.
When the fine sturctures of these tumors were compared with those of germ cells, seminomatous tumors had a close resemblance to germ cells in some aspects, but we could hardly find any resemblance between non-seminomatous tumors and germ cells, including human primordial germ cells.
Embryonal carcinomas have been proposed to be the stem cells of non-seminomatous germ cell tumors, but this theory should be reexamined further with the intratubular atypical germ cells.