Long-term influence of sialoadenectomy on reproductive performance of male mice

The influence of the submandibular gland, the major source of epithelial growth factor, on male reproduction in mice was studied by removing the submandibular gland (sialoadenectomy) and examining its effects on sperm production and copulation and fertility rates over an extended post-operation period. The removal of the submandibular gland caused a decrease in the number of epididymal spermatozoa 4 weeks after the operation; the decrease became significant (P < 0.05) 6-10 weeks after the operation compared with the sham operated and intact groups. There was no significant difference between prepuberal (30 days old) and postpuberal (60 days old) sialoadenectomy, indicating that the submandibular gland is not related to the maturation of the seminiferous tubules. The reduction in the number of epididymal spermatozoa was due to the decrease in number of spermatogonia and spermatocytes per Sertoli cell in the seminiferous tubules. When the reproductive performance was examined over 14 weeks, sialoadenectomized males showed a lower copulation rate and a significantly (P < 0.05) higher incidence of non-fertile copulation compared with the sham-operated and intact males. These results indicate that the submandibular gland and the secretion of epithelial growth factor from it affect spermatogenesis by acting on spermatogonial proliferation and sperm maturation.