Immunoreactivity of the salivary protein statherin in human male accessory sex glands.

BACKGROUND: Statherin is a small phosphoprotein chiefly studied for its protective roles towards teeth and oral tissues. Although generally considered as exclusively secreted by salivary glands, circumstantial evidences suggested that other tissues also produce it. This article first demonstrates statherin immunoreactivity in human prostate and seminal vesicles. METHODS: Surgical samples of prostate and seminal vesicles were fixed in a mixture of paraformaldehyde and glutaraldehyde, and embedded in Epon resin without previous osmication. Ultrathin sections were treated for the intracellular localization of statherin by means of an immunogold staining method. RESULTS: Reactive statherin was revealed in secreting cells of both seminal vesicle and prostate epithelia: labeling was found in secretory granules of seminal vesicle cells and in cytoplasmic vesicles of prostatic cells. CONCLUSIONS: The different staining patterns suggested that the two glands secrete statherin through different pathways. Prostate 71:671-674, 2011. © 2010 Wiley-Liss, Inc.

Electron microscopic immunogold localization of statherin in human minor salivary glands.

In this study, which supplements a recent article on the localization of statherin in human major salivary glands, we investigated the intracellular distribution of this peptide in minor salivary glands by immunogold cytochemistry at the electron microscopy level. In the lingual serous glands of von Ebner, gold particles were found in serous granules of all secreting cells, indicating that statherin is released through granule exocytosis. In buccal and labial glands, mostly composed of mucous tubuli, statherin reactivity was detected in the serous element, which represents only a small population of the glandular parenchyma. In these serous cells, however, statherin labeling was absent in secretory granules and restricted to small cytoplasmic vesicles near or partially fused with granules. Vesicle labeling could be related to the occurrence of an alternative secretory pathway for statherin in buccal and labial glands.

Oxytocin immunoreactivity in the human urethral (Littrè's) glands.

Oxytocin is a cyclic nonapeptide whose best known effects are stimulation of uterine smooth muscle cells during labor and of milk ejection during lactation. Circulating oxytocin originates from the hypothalamus, but its production has also been documented in peripheral tissues. Furthermore, seminal plasma also contains oxytocin, but its functional role is still unknown, although its secretion is generally ascribed to the prostate. In this study, we investigated the possibility that seminal oxytocin is also secreted by other exocrine glands of the human male genital tract. Intramural (Littrè's) glands isolated from bioptic specimens of normal urethrae were processed for immunogold localization of oxytocin. Immunostaining was detected in principal cells, with gold particles specifically found on secretory granules. Basal and endocrine cells were unstained. The present findings suggest that urethral glands not only produce the mucinous layer that protects and lubricates the urethral wall, but also are potential sources of other seminal components, such as oxytocin, which probably play still unclear roles in reproductive physiology.