Feinmesser M, Asa S L, Kovacs K, Low M J
Department of Pathology, St Michael's Hospital, University of Toronto, Ontario, Canada.
J Endocrinol. 1992 Nov;135(2):271-7. doi: 10.1677/joe.0.1350271.
We report the light microscopic, transmission and scanning electron microscopic features of the adrenal cortices in rats bearing a medullary thyroid carcinoma cell line transfected with a corticotrophin-releasing hormone (CRH) cDNA expression vector. The animals had elevated CRH, ACTH and corticosterone blood levels, involuted thymuses and markedly enlarged adrenal glands with prominent lipid-depleted cortices and dilated congested capillaries, similar to those of animals treated with ACTH. Using electron microscopy it was found that the enlarged fasciculata and reticularis zones were composed of large, compact cells with abundant smooth endoplasmic reticulum, prominent Golgi complexes, increased number of large mitochondria with focal loss of cristae and cavitation of the internal compartments, numerous lysosomes and prominent elongated microvilli. In addition, small cytoplasmic fragments were seen within the capillary lumina; these structures resembled microvilli that were apparently detached from adrenocortical cells and entered the blood stream via discontinuous endothelium of dilated capillaries. By scanning electron microscopy it was found that the cells had bulging surfaces with scattered pits and numerous long microvilli pointing in different directions. This animal model allows analysis of the effects of protracted CRH excess resembling tumoural CRH-dependent Cushing's syndrome in human patients. Our findings call attention to the role of microvilli in adrenocortical secretion. The increased number and size of microvilli has been thought to lead to an increase in the surface area of adrenocortical cells, thereby facilitating hormone discharge. The detachment of microvilli from adrenocortical cells may represent a form of apocrine secretion and may contribute to hypercorticosteronaemia in CRH excess.
我们报告了携带经促肾上腺皮质激素释放激素（CRH）cDNA表达载体转染的甲状腺髓样癌细胞系的大鼠肾上腺皮质的光学显微镜、透射电子显微镜和扫描电子显微镜特征。这些动物的血液中CRH、促肾上腺皮质激素（ACTH）和皮质酮水平升高，胸腺萎缩，肾上腺明显增大，皮质脂质缺失明显，毛细血管扩张充血，类似于用ACTH处理的动物。通过电子显微镜发现，增大的束状带和网状带由大而紧密的细胞组成，这些细胞具有丰富的滑面内质网、明显的高尔基体、大量线粒体数量增加，伴有嵴的局灶性缺失和内部腔室的空泡化，有许多溶酶体和明显伸长的微绒毛。此外，在毛细血管腔内可见小的细胞质碎片；这些结构类似于微绒毛，显然是从肾上腺皮质细胞脱离并通过扩张毛细血管的不连续内皮进入血流。通过扫描电子显微镜发现，细胞表面凸起，有散在的凹坑和许多指向不同方向的长微绒毛。这个动物模型可以分析长期CRH过量的影响，类似于人类患者中肿瘤性CRH依赖的库欣综合征。我们的发现提请注意微绒毛在肾上腺皮质分泌中的作用。微绒毛数量和大小的增加被认为会导致肾上腺皮质细胞表面积增加，从而促进激素释放。微绒毛从肾上腺皮质细胞的脱离可能代表一种顶浆分泌形式，可能导致CRH过量时的高皮质醇血症。
