Laminin in testicular germ cell tumours. An immunohistochemical study

Thirty-five testicular germ cell tumours comprising 16 yolk sac tumours, 15 embryonal carcinomas and 13 seminomas were examined for the presence and distribution of laminin using an indirect immunoperoxidase technique. In addition, nine normal yolk sacs and 23 carcinomas of the lung were studied. All the yolk sac tumours were positively stained for laminin. Both extra- and intracellular staining were found. Hyaline, eosinophilic material present within the tumours was positively stained, although with varying intensity. In 12 out of 15 embryonal carcinomas, laminin was found as a membrane staining but cytoplasmic staining also occurred. In 10 out of 13 classical seminomas, a membrane staining of many tumour cells was found, while cytoplasmic staining occurred in only a few seminomas. In all but one of the yolk sacs, laminin was present in the membrane beneath both the mesoblastic outer cell layer and the visceral endoderm. Intracellular staining was seen in some of the cells in both cell layers. In nine out of 23 carcinomas of the lung, laminin occurred extra- as well as intracellularly. Thus, this study showed that in normal yolk sacs the presence of laminin was not found to be particularly associated with any of the cell layers. Likewise, demonstration of laminin within yolk sac tumours did not define different patterns or subtypes of the yolk sac tumour. In addition, demonstration of laminin was not found to be useful in differentiating either between yolk sac tumours and embryonal carcinomas or between seminomas and non-seminomatous germ cell tumours. The findings add, however, interesting knowledge to histogenesis and embryogenesis.