Friend D S, Gilula N B
J Cell Biol. 1972 Jun;53(3):758-76. doi: 10.1083/jcb.53.3.758.
The fine structure and distribution of tight (zonula occludens) and gap junctions in epithelia of the rat pancreas, liver, adrenal cortex, epididymis, and duodenum, and in smooth muscle were examined in paraformaldehyde-glutaraldehyde-fixed, tracer-permeated (K-pyroantimonate and lanthanum), and freeze-fractured tissue preparations. While many pentalaminar and septilaminar foci seen in thin-section and tracer preparations can be recognized as corresponding to well-characterized freeze-fracture images of tight and gap junction membrane modifications, many others cannot be unequivocally categorized-nor can all freeze-etched aggregates of membrane particles. Generally, epithelia of exocrine glands (pancreas and liver) have moderate-sized tight junctions and large gap junctions, with many of their gap junctions basal to the junctional complex. In contrast, the adrenal cortex, a ductless gland, may not have a tight junction but does possess large gap junctions. Mucosal epithelia (epididymis and intestine) have extensive tight junctions, but their gap junctions are not as well developed as those of glandular tissue. Smooth muscle contains numerous small gap junctions The incidence, size, and configuration of the junctions we observed correlate well with the known functions of the junctions and of the tissues where they are found.
在经多聚甲醛 - 戊二醛固定、示踪剂渗透（焦锑酸钾和镧）以及冷冻断裂处理的组织标本中，研究了大鼠胰腺、肝脏、肾上腺皮质、附睾和十二指肠上皮以及平滑肌中紧密连接（闭锁小带）和缝隙连接的精细结构与分布。虽然在超薄切片和示踪剂标本中看到的许多五片层和七片层结构可被识别为对应于紧密连接和缝隙连接膜修饰的特征明确的冷冻断裂图像，但许多其他结构无法明确归类，膜颗粒的所有冷冻蚀刻聚集体也是如此。一般来说，外分泌腺（胰腺和肝脏）的上皮具有中等大小的紧密连接和大的缝隙连接，其许多缝隙连接位于连接复合体的基部。相比之下，无管腺肾上腺皮质可能没有紧密连接，但确实有大的缝隙连接。黏膜上皮（附睾和肠道）有广泛的紧密连接，但其缝隙连接不如腺组织发达。平滑肌含有许多小的缝隙连接。我们观察到的连接的发生率、大小和形态与连接以及发现它们的组织的已知功能密切相关。
