Russell L D
Am J Anat. 1979 Jun;155(2):259-79. doi: 10.1002/aja.1001550208.
Structures termed tubulobulbar complexes are known to be formed by adjoining Sertoli cells at the level of the blood-testis barrier (Russell and Clermont, '76). Here, long (2-4 micrometer) tubular evaginations of one Sertoli cell, which end in bulbous dilations, are seen in corresponding invaginations of a neighboring Sertoli cell. In most regions of the tubular and bulbous portions of the complex, the Sertoli plasma membranes were found to be separated by a 4-5-nm intercellular space, but in some areas the membranes converged to form tight and gap junctions. The numbers, distribution and properties of tubulobulbar complexes were studied in relation to the cycle of the seminiferous epithelium. From the data obtained it was concluded that tubulobulbar complexes develop and undergo regressive changes during the spermatogenic cycle. Most complexes arise during the early stages of the cycle (Stages II-V) and develop large bulbous endings. Developing tubulobulbar complexes consist of short evaginations of one Sertoli cell which face a bristle-coated pit of the opposing Sertoli cell. At midcycle (Stages VI-VII) most show regressive changes and are eventually resorbed as a consequence of the action of nearby Sertoli lysosomes. Once resorbed, the probability of seeing a tubulobulbar complex in thin sections decreases from 4- to 8-fold. The few tubulobulbar complexes which remain past this period (Stages VII-XIV-I) usually lack bulbous endings and are fequently seen above type A spermatogonia. The data suggest that small fragments of cytoplasm and plasma membrane (including junctional surfaces) are lost from one Sertoli cell as a result of the degradative processes occurring in a neighboring Sertoli cell. Tubulobulbar resorption is discussed in relation to the impending breakdown of the blood-testis barrier above spermatocytes as these cells move upward. The possible significance of the cyclic resorption of tight and gap junctional sites between Sertoli cells is also discussed.
已知被称为球管复合体的结构是由紧邻血睾屏障水平的支持细胞形成的（拉塞尔和克莱蒙特，1976年）。在这里，可以看到一个支持细胞的长（2 - 4微米）管状突起，其末端为球状扩张，位于相邻支持细胞的相应凹陷处。在复合体的管状和球状部分的大多数区域，发现支持细胞质膜被4 - 5纳米的细胞间隙分隔，但在某些区域，膜会汇聚形成紧密连接和缝隙连接。研究了球管复合体的数量、分布和特性与生精上皮周期的关系。根据获得的数据得出结论，球管复合体在生精周期中发育并经历退行性变化。大多数复合体在周期的早期阶段（II - V期）出现，并发育出大的球状末端。正在发育的球管复合体由一个支持细胞的短突起组成，这些突起面对相对支持细胞的被毛小窝。在周期中期（VI - VII期），大多数复合体显示退行性变化，并最终由于附近支持细胞溶酶体的作用而被吸收。一旦被吸收，在薄切片中看到球管复合体的概率会降低4至8倍。在这个时期之后（VII - XIV - I期）仍存在的少数球管复合体通常没有球状末端，并且经常在A型精原细胞上方看到。数据表明，由于相邻支持细胞中发生的降解过程，一个支持细胞会丢失少量细胞质和质膜（包括连接表面）。讨论了球管复合体的吸收与随着精母细胞向上移动血睾屏障即将破裂的关系。还讨论了支持细胞之间紧密连接和缝隙连接位点周期性吸收的可能意义。
