Serum testosterone, estradiol, and steroidogenesis-related gene expression levels in Hu sheep with different scrotal circumference

To understand the differences in steroidogenesis and spermatogenic environment of 165-day-old Hu sheep with different scrotal circumference, 18 lambs were selected and equally divided according to scrotal circumference into the small group S, (18.53 ± 0.42) cm and large group L, (27.29 ± 1.13) cm circumference groups. The results showed that: 1) Testes weight, testes volume, testicular index, epididymides weight, the diameter of seminiferous tubes, and the number of sperm in the cauda epididymis in group L were extremely significantly higher than those in the S group (P < 0.01). 2) The concentrations of serum testosterone and estradiol were significantly increased (P < 0.05) in group L compared with group S. 3) The mRNA expression levels of gonadotropin receptors (FSHR and LHR), androgen binding protein (ABP), steroidogenesis-related genes (STAR, HSD3B1, and CYP19A1), and the HSD3B1 protein in group L were significantly higher than those in group S (P < 0.05). The expression of aromatase gene CYP11A1 was also upregulated in group L (P = 0.086). In conclusion, the expression levels of steroidogenesis-related proteins and genes in 165-day-old Hu sheep lambs with large scrotal circumference were significantly higher than in those with small scrotal circumference, and stimulated testosterone and estradiol secretion, thereby providing a better spermatogenic environment and contributing to testicular development and spermatogenesis.