Ziwuling black goats are typically found in loess plateaus regions and the Ziwuling Nature Reserve. Cryptorchidism is a common disease in this inbred goat, and its pathogenesis has been linked with the expression of insulin‐like factor 3 (INSL‐3). Therefore, this study aimed to investigate anatomical alterations caused by cryptorchism and the expression and distribution of INSL‐3 in normal and cryptorchid testicular tissues. The testicular tissues of 6‐month‐old Ziwuling black goats were collected for microscopic analyses using histochemical, immunohistochemical, immunofluorescence and biometrical methods, as well as Western blotting to compare the expression and distribution of INSL‐3. A lower expression of INSL‐3 was observed in cryptorchid compared with normal testicular tissues (p < .01). Cryptorchidism caused a significant reduction in layers of spermatogenic epithelium and tubule areas in Ziwuling black goat (p < .01). The interstitial to seminiferous tubule area ratio was larger in cryptorchid than in normal group. Periodic Acid‐Schiff (PAS) staining revealed pronounced positive bands in the interstitial tissue, while positive Alcian blue (AB) staining was not clear, and AB‐PAS staining revealed a positive red band in the basement membrane of cryptorchid group. Immunofluorescence revealed a strong signal of INSL‐3 expression in Sertoli and peritubular myoid cells, and moderate signal in Leydig and spermatogenic cells in the normal group. However, in cryptorchid testicular tissues, the signal of INSL‐3 expression was strong in primary spermatocytes, occasional in Sertoli cells, limited in Leydig cells and absent in peritubular myoid cells. Furthermore, immunohistochemistry showed that INSL‐3 expression was higher in normal testes compared with cryptorchid testicular tissues (p < .05), especially in primary spermatocytes and Sertoli cells. Collectively, our results indicate that cryptorchidism is closely related to the disorder of acid glycoprotein metabolism and the reduction in release of INSL‐3 from Leydig cells. Moreover, Sertoli and peritubular myoid cells are crucial for INSL signalling and could underpin further research on the mechanism of cryptorchidism in animal.

中文翻译：

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子午岭黑山羊正常和隐睾睾丸中INSL-3蛋白的表达

子午岭黑山羊通常分布在黄土高原地区和子午岭自然保护区。隐睾是这种近交山羊的常见疾病，其发病机制与胰岛素样因子3（INSL-3）的表达有关。因此，本研究旨在研究隐睾引起的解剖学改变以及INSL-3在正常和隐睾睾丸组织中的表达和分布。收集6月龄紫武岭黑山羊的睾丸组织，使用组织化学、免疫组织化学、免疫荧光和生物特征方法以及蛋白质印迹法进行显微镜分析，以比较INSL-3的表达和分布。与正常睾丸组织相比，隐睾中观察到的 INSL-3 表达较低（p < .01)。隐睾使子午岭黑山羊生精上皮层和小管区显着减少（p < .01)。隐睾组间质与生精小管面积比大于正常组。高碘酸-希夫（PAS）染色显示间质组织有明显阳性带，而阿尔辛蓝（AB）染色阳性不清晰，AB-PAS染色显示隐睾组基底膜有红色阳性带。免疫荧光显示正常组的支持和管周肌样细胞中 INSL-3 表达强信号，Leydig 和生精细胞中信号中等。然而，在隐睾睾丸组织中，INSL-3 表达信号在初级精母细胞中较强，在支持细胞中偶见，在 Leydig 细胞中有限，在管周肌样细胞中不存在。此外，p  < .05)，尤其是在初级精母细胞和支持细胞中。总的来说，我们的研究结果表明，隐睾与酸性糖蛋白代谢紊乱和 Leydig 细胞释放 INSL-3 的减少密切相关。此外，支持和管周肌样细胞对于 INSL 信号传导至关重要，可以支持进一步研究动物隐睾症的机制。