Leivo I, Laurila P, Wahlström T, Engvall E
Department of Pathology, University of Helsinki, Finland.
Lab Invest. 1989 Jun;60(6):783-90.
Merosin is a novel tissue-specific basement membrane-associated protein found in basement membranes of trophoblast, striated muscle and Schwann cells. In placental extracts, the immuno-reactivity for merosin was detected in a protein band of 80 kilodaltons, and a 65 kilodalton polypeptide fragment of merosin could be isolated from proteolytic digests of placenta. In the present study, we describe the expression of merosin in human choriocarcinomas and normal placentas using immunoperoxidase staining of paraffin-embedded tissues. All five choriocarcinomas studied show immunoreactivity for merosin. Tumor cells, exhibiting the morphology typical of the intermediate trophoblast, stained distinctly for merosin. The cytotrophoblast and syncytiotrophoblast cells in these tumors showed negligible or no staining. In second and third trimester human placentas, merosin immunoreactivity was found in large extravillar mononuclear trophoblast cells of the basal plate as well as in the trophoblast basement membranes of the chorionic villi. The results indicate that merosin is mainly expressed in the intermediate trophoblast cells of both neoplastic and normal origin, whereas almost no expression is seen in cytotrophoblast and syncytiotrophoblast. Consequently, it is suggested that the intermediate trophoblast may represent a third, independently differentiated trophoblastic cell type.
巢蛋白是一种新发现的组织特异性基底膜相关蛋白，存在于滋养层、横纹肌和施万细胞的基底膜中。在胎盘提取物中，在一条80千道尔顿的蛋白条带中检测到巢蛋白的免疫反应性，并且可以从胎盘的蛋白水解消化物中分离出巢蛋白的一个65千道尔顿的多肽片段。在本研究中，我们使用石蜡包埋组织的免疫过氧化物酶染色来描述巢蛋白在人绒毛膜癌和正常胎盘中的表达。所研究的所有五个绒毛膜癌均显示出对巢蛋白的免疫反应性。表现出中间型滋养层典型形态的肿瘤细胞，对巢蛋白染色明显。这些肿瘤中的细胞滋养层细胞和合胞体滋养层细胞染色可忽略不计或无染色。在妊娠中期和晚期的人胎盘中，在基底板的大的绒毛外单核滋养层细胞以及绒毛膜绒毛的滋养层基底膜中发现了巢蛋白免疫反应性。结果表明，巢蛋白主要在肿瘤性和正常来源的中间型滋养层细胞中表达，而在细胞滋养层和合胞体滋养层中几乎未见表达。因此，有人提出中间型滋养层可能代表第三种独立分化的滋养层细胞类型。
