Effect of Melatonin on Telocytes in the Seminal Vesicle of the Soay Ram: An Immunohistochemical, Ultrastructural and Morphometrical Study

Abstract

Telocytes (TCs) are a special type of interstitial cell with characteristic cellular processes that are described in many organs. The current study aimed to investigate TCs in seminal vesicles of the Soay ram responding to melatonin treatment during the nonbreeding season by conventional immunohistochemical stains, and to detect the ultrastructural and morphometrical changes of TCs. TCs in the control group showed a broad range of staining affinity and also reacted positively to CD117/c-kit, CD34, desmin, S-100 protein, and progesterone and estrogen receptors alpha, while after melatonin treatment a strong reaction against these 6 antibodies was recorded. Electron microscopically, TCs in the control group were characterized by a small cell body with distinct long cytoplasmic extensions called telopodes (Tps). Tps had alternation of the thin segment (podomers) and dilated segments (podoms), in which the latter accommodate mitochondria, rough endoplasmic reticulum and caveolae. TCs and their Tps were interconnected by homo- and heterocellular junctions and form a wide network to communicate between different cell types. Tps showed close contact with immune cells, progenitor stem cells, smooth muscle cells and other interstitial cells. Melatonin caused a significant increase in the number of TCs, length of Tps, and number and diameter of secretory vesicles. Also, the melatonin-treated group showed exaggerated secretory activity in the form of a massive release of secretory vesicles from Tps. Moreover, Tps showed an increase in their contact with blood and lymphatic capillaries, nerve endings and Schwann cells. In addition, the shedding of secretory structures (exosomes, ectosomes, and multivesicular bodies) was greater from Tps, which were involved in paracrine signaling in the melatonin-treated group. The length and ramifications of Tps together with the intercellular junctions and the releasing of shed vesicles or exosomes assumed an essential role of TCs in intercellular signaling and coordination. On the basis of their distribution and morphology, we investigated whether the different locations of TCs could be associated with different roles.

Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis

“…While the immunological actions of melatonin are well documented under many experimental conditions, its actions on the specific immune cells and exosomes of the tumor microenvironment have gone uninvestigated. In a study designed to examine vesicle release from normal interstitial cells of the seminal vesicle, melatonin influenced shedding of exosomes (also of ectosomes and multivesicular bodies) leading to changes in paracrine signaling of adjacent cells [376]. Considering the significance of the immune system to tumor cell biology, examining the immune state of both cells and exosomes of the microenvironment of tumor cells would be informative in terms of understanding the role of melatonin in determining tumor progression [377].…”

Recently discovered interstitial cells termed telocytes: distinguishing cell-biological and histological facts from fictions

“…Telocytes in mammals have also been intensely studied. They have been detected in livestock, such as sheep (Abd-Elhafeez et al 2017), in pets, like dogs (Xu et al 2016), and in laboratory animals, like guinea pigs (Nguyen et al 2011), rats (Hatta et al 2012) and mice (Ye et al 2017). Moreover, telocytes have been found also in invertebrates; in 2017, the presence of telocytes was confirmed in leeches (Hirudo medicinalis) (Pulze et al 2017).…”

Localization of telocytes in rabbits testis: Histological and immunohistochemical approach

“…In semi‐thin sections, telopodes displayed an alternation between thin segments (podomeres) and numerous distended segments (podoms) forming a moniliform appearance or beads‐like structure (Abd‐Elhafeez et al, ; Abd‐Elhafeez and Soliman, ; Bei et al, ; Manole and Simionescu, ; Yang et al, ).…”

“…In the reproductive system, TCs are distributed in the female reproductive organs including: myometrium (Cretoiu et al, ; Cretoiu et al, ) and fallopian tubes (Cretoiu et al, ). In the male reproductive organs, TCs could be identified in the prostate (Corradi et al, ) and seminal vesicle (Abd‐Elhafeez et al, ).…”