Garza M M, Schwarz L K, Bonner J M, Boockfor F R
Department of Anatomy and Cell Biology, Medical University of South Carolina, Charleston 29425-2204.
Endocrinology. 1991 Apr;128(4):1869-74. doi: 10.1210/endo-128-4-1869.
Recent studies from our laboratory demonstrated clearly that only a portion of all Sertoli cells secrete transferrin (TF). These findings raised the possibility that differences in the functional type of Sertoli cells from one location to another may account in part for the stage-related variation in TF release along the seminiferous tubule. In order to address this, Sertoli cells derived from tubule segments corresponding to stages III-V, VII, IX-XI, and XIII of the seminiferous epithelial cycle were subjected to reverse hemolytic plaque assays to determine whether the proportion of TF cells present in those segments were similar or different. We found 21.4 +/- 1.8%, 20.3 +/- 2.0%, 48.3 +/- 2.5%, and 49.2 +/- 3.2% of all cells secreted TF in III-V, VII, IX-XI, and XIII staged segments, respectively. Results obtained from immunocytochemical staining of cells from different sections agreed well with those obtained with plaque assays, indicating that we had detected most, if not all, TF cells in these cultures. In additional experiments, we found that cultured cells from stage III-V and VII responded to FSH or isoproterenol with a large increase in the rate of TF plaque formation, whereas cells from IX-XI and XIII segments appeared to be unaffected. In contrast, bovine fibroblast growth factor caused a marked increase in the rate of TF plaque formation with IX-XI cells and only a slight increase with cells from III-V staged segments. Thus, the manner in which Sertoli cells respond to several modulatory agents appears not only to be stage-dependent, but also to be specific to the agent in question. When taken together, our observations demonstrate that cultured TF secretors obtained from different staged segments of the seminiferous tubule differ in proportion and responsiveness. These findings, when viewed in light of reports of a constant number of Sertoli cells along the seminiferous tubule, suggest that Sertoli cells may acquire and lose the ability to secrete TF or respond to modulation as the seminiferous cycle progresses.
我们实验室最近的研究清楚地表明，所有支持细胞中只有一部分分泌转铁蛋白（TF）。这些发现提出了一种可能性，即不同位置的支持细胞功能类型差异可能部分解释了生精小管中TF释放的阶段相关变化。为了解决这个问题，对来自生精上皮周期III-V期、VII期、IX-XI期和XIII期相应小管段的支持细胞进行反向溶血空斑试验，以确定这些段中存在的TF细胞比例是相似还是不同。我们发现，在III-V期、VII期、IX-XI期和XIII期段中，分别有21.4±1.8%、20.3±2.0%、48.3±2.5%和49.2±3.2%的所有细胞分泌TF。来自不同切片细胞的免疫细胞化学染色结果与空斑试验结果非常吻合，表明我们在这些培养物中检测到了大多数（如果不是全部）TF细胞。在额外的实验中，我们发现来自III-V期和VII期的培养细胞对促卵泡激素（FSH）或异丙肾上腺素反应时，TF空斑形成率大幅增加，而来自IX-XI期和XIII期段的细胞似乎不受影响。相比之下，牛成纤维细胞生长因子使IX-XI期细胞的TF空斑形成率显著增加，而对III-V期段细胞仅略有增加。因此，支持细胞对几种调节因子的反应方式似乎不仅取决于阶段，而且还针对所讨论的因子具有特异性。综合来看，我们的观察结果表明，从生精小管不同阶段段获得的培养TF分泌细胞在比例和反应性方面存在差异。鉴于沿生精小管支持细胞数量恒定的报道，这些发现表明，随着生精周期的进展，支持细胞可能获得或丧失分泌TF或对调节作出反应的能力。
