Are telocytes related to maintenance of vascular homeostasis in normal and pathological aorta?

The telocyte (TC) is a new interstitial cell type described in a wide variety of organs and loose connective tissues around small vessels, but its presence in large arteries remains unexplored. TCs have small cell bodies and remarkably thin, long, moniliform processes called telopods (Tps). Using transmission electron microscopy and immunofluorescence, we identified TCs in normal human thoracic aortas and in those with aneurysm or acute dissection (TAAD). In normal aortas the TCs were distributed throughout the connective tissue of the adventitial layer, in its innermost portion and at the zone of transition with the medial layer, with their long axes oriented parallel to the external elastic lamellae, forming a three-dimensional network, without prevalence in the media layer. In contrast, TAAD TCs were present in the medial layer and in regions of neovascularization. The most important feature of the adventitia of diseased aortas was the presence of numerous contacts between TCs and stem cells, including vascular progenitor cells. Although the biologically functional correlations need to be elucidated, the morphological observations presented here provide strong evidence of the involvement of TCs in maintaining vascular homeostasis in pathological situations of tissue injury.

Ultrastructural characteristics and morphological relationships of cardiomyocytes and telocytes in the myocardium of the bullfrog (Rana catesbeiana).

Telocytes (TCs) are distinctive interstitial cells due to their characteristic structures and heterogeneity. They are suggested to participate in tissue repair/regeneration. TCs have been identified in many organs of various mammals. However, data on TCs in lower animals are still very limited. In this work, TCs were identified in the myocardium of the bullfrog (Rana catesbeiana) by light and transmission electron microscopy (TEM). The structural relationships between TCs and neighbouring cell types were measured using the ImageJ (FiJi) morphometric software. TCs with slender Tps (telepodes) were located around cardiomyocytes (CMC). TEM revealed TCs with long Tps in the stroma between CMC. The homocellular tight junctions were observed between the Tps. The Tps were also very close to the neighbouring CMC. The distance between Tps and CMC was 0.15 ± 0.08 µm. Notably, Tps were observed to adhere to the periphery of the satellite cells. The Tps and the satellite cells established heterocellular structural connections by tight junctions. Additionally, Tps were frequently observed in close proximity to mast cells (MCs). The distance between the Tps and the MCs was 0.19 ± 0.09 µm. These results confirmed that TCs are present in the myocardium of the bullfrog, and that TCs established structural relationships with neighbouring cell types, including satellite cells and MCs. These findings provide the anatomical evidence to support the note that TCs are involved in tissue regeneration.

Telocytes in Human Embryonic Development: A Preliminary Microscopic Anatomy Study / Telocitos en el Desarrollo Embrionario Humano: Un Estudio Preliminar de Anatomía Microscópica

SUMMARY: Telocytes are a cell population described in 2011 with a multitude of functions such as tissue support, regulation of stem cell niches or intercellular signal transmission. However, there are no studies about their embryonic origin, their function in development, or their moment of appearance. The objective of this work is to try to answer these questions through histological and immunofluorescence studies with samples from the embryological collection of the Department of Anatomy of the University of Granada. In the results obtained, as demonstrated by immunofluorescence for CD34, the presence of these cells can be seen in the fourth week of embryonic development in the perinotochordal region. Its presence is evident from the sixth week of development in a multitude of organs such as the heart, skeletal muscle tissue and supporting tissue of various organs such as the kidney, brain or pericardium. Its function seems to be when the embryonic histological images are analyzed in an evolutionary way, to act as a scaffold or scaffold for the subsequent population by mature tissue elements. In conclusion, telocytes appear at a very early stage of embryonic development and would have a fundamental role in it as scaffolding and directors of organ and tissue growth.

Los telocitos son una población celular descrita en 2011 con multitud de funciones como el sostén tisular, la regulación de los nichos de células madre o la transmisión de señales intercelulares. Sin embargo, no existen estudios acerca del origen embrionario de los mismos, su función en el desarrollo ni su momento de aparición. El objetivo de este trabajo es tratar de responder a estos interrogantes mediante estudios histológicos y por inmunofluorescencia con muestras de la colección embriológica del Departamento de Anatomía de la Universidad de Granada. En los resultados se puede observar como se demuestra mediante inmunofluorescencia para CD34, la presencia de estas células en la cuarta semana del desarrollo embrionario en la región perinotocordal. Su presencia se evidencia a partir de la sexta semana del desarrollo en multitud de órganos como corazón, tejidos músculo esqueléticos y tejidos de sostén de diversos órganos como riñón, encéfalo o pericardio. Su función parece ser al ser analizadas las imágenes histológicas embrionarias de forma evolutiva, la de actuar como un andamiaje o scafold para el posterior poblamiento por elementos tisulares maduros. Como conclusión, los telocitos aparecen en un momento muy precoz del desarrollo embrionario y presentarían una función fundamental en el mismo como andamiajes y directores del crecimiento de los órganos y tejidos.

Interstitial Cell Dysregulation in Allergic Contact Dermatitis: A Morphodynamic Study of Novel Interstitial Cell Telocytes.

Allergic contact dermatitis (ACD) is an occupation-dependent skin disease that afflicts humans with recurrent, non-specific episodes. Telocyte (TC) is a novel interstitial cell discovered in recent years and, together with fibroblasts, constitutes the predominant interstitial cell population in the skin. The purpose of this study was to investigate the morphodynamic changes of interstitial cells, especially TCs, in the skin during the development and treatment of ACD by histological and microscopic scientific methods. Hematoxylin-eosin staining, Masson staining, immunohistochemistry (IHC), immunofluorescence (IF), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to track morphodynamic changes in interstitial cells during the development and treatment in the ACD-involved skin induced by 2,4-dinitrochlorobenzene (DNCB). The results demonstrated that TCs were mainly present around dermal collagen fibers, perivascular (except dermal papillary vascular loop), and skin appendages, which expressed CD34+, Vimentin+, PDGFR-α+, and α-SMA-. The absence of TCs during ACD development and after ACD recovery causes dermal interstitial cell dysregulation. The special anatomical relationships between TCs, immune cells, and follicular stem cells were also revealed, suggesting their potential dermatitis-regulating function. In a nutshell, our results provide morphodynamic evidence for the process of ACD development and recovery and offer potential cytological ideas for ACD treatment.

Identification of telocytes in the oviduct of the mare.

Telocytes (TCs), a recently discovered special type of stromal cells, have been identified in many organs of many species, including the female and male reproductive system, with proposed multiple potential bio-functions such as homeostasis, immunomodulation, tissue remodeling and regeneration, embryogenesis, angiogenesis and even tumorigenesis. The aim of this study was to investigate the existence, and characteristics of telocytes in normal equine oviduct. To identify them, we used routine light microscopy, non-conventional light microscopy (NCLM), transmission electron microscopy (TEM), and immunohistochemistry. We found that telocytes of the equine oviduct can be recognized in fixed specimens by light microscopy (methylene blue staining), with more details on Epon semi-thin sections (toluidine blue staining) by NCLM, and that they showed positive immunostaining for CD34. The telocytes, with their typical long and moniliform prolongations, formed networks in the stromal space of the submucosa, muscular and serosa layers, particularly in the lamina propia where they were observed in greater quantity. By TEM we have also confirmed the presence of cells ultrastructurally identifiable as telocytes (cells with telopodes alternating podomers and podoms) in the aforementioned locations. Direct intercellular contacts between epithelial cells and neighboring telocytes were evidenced. EIn conclusion, we demonstrated that telocytes are present in the equine oviduct as previously reported in other species. The potential implication of telocytes in multiple potential functions of physiological and pathological processes deserves further investigation.

Telocytes in Cutaneous Biology: A Reappraisal / Los telocitos en la biología cutánea: revaluación

The telocytes (TCs) are novel interstitial cells that have been overlooked for a long time due to their histologic similarity to other stromal cells. TCs can be separated from the stromal cells based on their distinct immunohistochemical, ultrastructural, and molecular features. Functionally, TCs are involved in the tissue renewal, mechanical support, and immune modulation. These cells are also involved in the signal transduction either through their direct interactions with the neighboring cells or through the paracrine signaling via extracellular vesicles. TCs are damaged in several inflammatory and fibrotic conditions such as ulcerative colitis, Crohn's disease, hepatic fibrosis, psoriasis, and systemic sclerosis. The transplantation of TCs in the damaged tissue can promote tissue regeneration. Therefore, enhancing tissue TCs either by their transplantation or by promoting their survival and growth using novel medications represents novel therapeutic strategy in the future. In this review, we addressed several aspects of TCs including their origin, distribution, morphologic features, and functions. We also discussed their involvement of the cutaneous TCs in the development various pathologic conditions (AU)

Los telocitos (TC) son células intersticiales noveles que han sido subvaloradas durante mucho tiempo debido a su similitud histológica con otras células estromales. Los TC pueden separarse de las células estromales debido a sus distintas características inmunohistoquímicas, ultraestructurales y moleculares. A nivel funcional, los TC están implicados en la renovación tisular, el soporte mecánico y la modulación inmune. Dichas células están implicadas también en la transducción de señal, bien mediante sus interacciones directas con las células circundantes, o bien mediante la señalización paracrina, a través de las vesículas extracelulares. Los TC se ven dañados en ciertas situaciones inflamatorias y fibróticas tales como colitis ulcerosa, enfermedad de Crohn, fibrosis hepática, psoriasis y esclerosis sistémica. El trasplante de TC en el tejido dañado puede promover la regeneración tisular. Por tanto, mejorar los TC tisulares mediante trasplante o promoción de su supervivencia y crecimiento, utilizando medicaciones novedosas, representa una estrategia terapéutica innovadora para el futuro. En esta revisión abordamos diversos aspectos de los TC, incluyendo su origen, su distribución, sus características morfológicas y sus funciones. También tratamos la implicación de los TC cutáneos en el desarrollo de diversas situaciones patológicas (AU)

[Artículo traducido] Los telocitos en la biología cutánea: revaluación / Telocytes in Cutaneous Biology: A Reappraisal

Los telocitos (TC) son células intersticiales noveles que han sido subvaloradas durante mucho tiempo debido a su similitud histológica con otras células estromales. Los TC pueden separarse de las células estromales debido a sus distintas características inmunohistoquímicas, ultraestructurales y moleculares. A nivel funcional, los TC están implicados en la renovación tisular, el soporte mecánico y la modulación inmune. Dichas células están implicadas también en la transducción de señal, bien mediante sus interacciones directas con las células circundantes, o bien mediante la señalización paracrina, a través de las vesículas extracelulares. Los TC se ven dañados en ciertas situaciones inflamatorias y fibróticas tales como colitis ulcerosa, enfermedad de Crohn, fibrosis hepática, psoriasis y esclerosis sistémica. El trasplante de TC en el tejido dañado puede promover la regeneración tisular. Por tanto, mejorar los TC tisulares mediante trasplante o promoción de su supervivencia y crecimiento, utilizando medicaciones novedosas, representa una estrategia terapéutica innovadora para el futuro. En esta revisión abordamos diversos aspectos de los TC, incluyendo su origen, su distribución, sus características morfológicas y sus funciones. También tratamos la implicación de los TC cutáneos en el desarrollo de diversas situaciones patológicas (AU)

The telocytes (TCs) are novel interstitial cells that have been overlooked for a long time due to their histologic similarity to other stromal cells. TCs can be separated from the stromal cells based on their distinct immunohistochemical, ultrastructural, and molecular features. Functionally, TCs are involved in the tissue renewal, mechanical support, and immune modulation. These cells are also involved in the signal transduction either through their direct interactions with the neighboring cells or through the paracrine signaling via extracellular vesicles. TCs are damaged in several inflammatory and fibrotic conditions such as ulcerative colitis, Crohn's disease, hepatic fibrosis, psoriasis, and systemic sclerosis. The transplantation of TCs in the damaged tissue can promote tissue regeneration. Therefore, enhancing tissue TCs either by their transplantation or by promoting their survival and growth using novel medications represents novel therapeutic strategy in the future. In this review, we addressed several aspects of TCs including their origin, distribution, morphologic features, and functions. We also discussed their involvement of the cutaneous TCs in the development various pathologic conditions (AU)

Telocytes in Cutaneous Biology: A Reappraisal. / [Artículo traducido] Los telocitos en la biología cutánea: revaluación.

The telocytes (TCs) are novel interstitial cells that have been overlooked for a long time due to their histologic similarity to other stromal cells. TCs can be separated from the stromal cells based on their distinct immunohistochemical, ultrastructural, and molecular features. Functionally, TCs are involved in the tissue renewal, mechanical support, and immune modulation. These cells are also involved in the signal transduction either through their direct interactions with the neighboring cells or through the paracrine signaling via extracellular vesicles. TCs are damaged in several inflammatory and fibrotic conditions such as ulcerative colitis, Crohn's disease, hepatic fibrosis, psoriasis, and systemic sclerosis. The transplantation of TCs in the damaged tissue can promote tissue regeneration. Therefore, enhancing tissue TCs either by their transplantation or by promoting their survival and growth using novel medications represents novel therapeutic strategy in the future. In this review, we addressed several aspects of TCs including their origin, distribution, morphologic features, and functions. We also discussed their involvement of the cutaneous TCs in the development various pathologic conditions.

Telocytes in Cutaneous Biology: A Reappraisal.

The telocytes (TCs) are novel interstitial cells that have been overlooked for a long time due to their histologic similarity to other stromal cells. TCs can be separated from the stromal cells based on their distinct immunohistochemical, ultrastructural, and molecular features. Functionally, TCs are involved in the tissue renewal, mechanical support, and immune modulation. These cells are also involved in the signal transduction either through their direct interactions with the neighboring cells or through the paracrine signaling via extracellular vesicles. TCs are damaged in several inflammatory and fibrotic conditions such as ulcerative colitis, Crohn's disease, hepatic fibrosis, psoriasis, and systemic sclerosis. The transplantation of TCs in the damaged tissue can promote tissue regeneration. Therefore, enhancing tissue TCs either by their transplantation or by promoting their survival and growth using novel medications represents novel therapeutic strategy in the future. In this review, we addressed several aspects of TCs including their origin, distribution, morphologic features, and functions. We also discussed their involvement of the cutaneous TCs in the development various pathologic conditions.

Dermal Telocytes: A Different Viewpoint of Skin Repairing and Regeneration.

Fifteen years after their discovery, telocytes (TCs) are yet perceived as a new stromal cell type. Their presence was initially documented peri-digestively, and gradually throughout the interstitia of many (non-)cavitary mammalian, human, and avian organs, including skin. Each time, TCs proved to be involved in diverse spatial relations with elements of interstitial (ultra)structure (blood vessels, nerves, immune cells, etc.). To date, transmission electron microscopy (TEM) remained the single main microscopic technique able to correctly and certainly attest TCs by their well-acknowledged (ultra)structure. In skin, dermal TCs reiterate almost all (ultra)structural features ascribed to TCs in other locations, with apparent direct implications in skin physiology and/or pathology. TCs' uneven distribution within skin, mainly located in stem cell niches, suggests involvement in either skin homeostasis or dermatological pathologies. On the other hand, different skin diseases involve different patterns of disruption of TCs' structure and ultrastructure. TCs' cellular cooperation with other interstitial elements, their immunological profile, and their changes during remission of diseases suggest their role(s) in tissue regeneration/repair processes. Thus, expanding the knowledge on dermal TCs could offer new insights into the natural skin capacity of self-repairing. Moreover, it would become attractive to consider that augmenting dermal TCs' presence/density could become an attractive therapeutic alternative for treating various skin defects.

Scleroderma-like Impairment in the Network of Telocytes/CD34+ Stromal Cells in the Experimental Mouse Model of Bleomycin-Induced Dermal Fibrosis.

Considerable evidence accumulated over the past decade supports that telocytes (TCs)/CD34+ stromal cells represent an exclusive type of interstitial cells identifiable by transmission electron microscopy (TEM) or immunohistochemistry in various organs of the human body, including the skin. By means of their characteristic cellular extensions (telopodes), dermal TCs are arranged in networks intermingled with a multitude of neighboring cells and, hence, they are thought to contribute to skin homeostasis through both intercellular contacts and releasing extracellular vesicles. In this context, fibrotic skin lesions from patients with systemic sclerosis (SSc, scleroderma) appear to be characterized by a disruption of the dermal network of TCs, which has been ascribed to either cell degenerative processes or possible transformation into profibrotic myofibroblasts. In the present study, we utilized the well-established mouse model of bleomycin-induced scleroderma to gain further insights into the TC alterations found in cutaneous fibrosis. CD34 immunofluorescence revealed a severe impairment in the dermal network of TCs/CD34+ stromal cells in bleomycin-treated mice. CD31/CD34 double immunofluorescence confirmed that CD31-/CD34+ TC counts were greatly reduced in the skin of bleomycin-treated mice compared with control mice. Ultrastructural signs of TC injury were detected in the skin of bleomycin-treated mice by TEM. The analyses of skin samples from mice treated with bleomycin for different times by either TEM or double immunostaining and immunoblotting for the CD34/α-SMA antigens collectively suggested that, although a few TCs may transition to α-SMA+ myofibroblasts in the early disease stage, most of these cells rather undergo degeneration, and then are lost. Taken together, our data demonstrate that TC changes in the skin of bleomycin-treated mice mimic very closely those observed in human SSc skin, which makes this experimental model a suitable tool to (i) unravel the pathological mechanisms underlying TC damage and (ii) clarify the possible contribution of the TC loss to the development/progression of dermal fibrosis. In perspective, these findings may have important implications in the field of skin regenerative medicine.

Telocytes in the human ascending aorta: Characterization and exosome-related KLF-4/VEGF-A expression.

Telocytes (TCs), a novel interstitial cell entity promoting tissue regeneration, have been described in various tissues. Their role in inter-cellular signalling and tissue remodelling has been reported in almost all human tissues. This study hypothesizes that TC also contributes to tissue remodelling and regeneration of the human thoracic aorta (HTA). The understanding of tissue homeostasis and regenerative potential of the HTA is of high clinical interest as it plays a crucial role in pathogenesis from aortic dilatation to lethal dissection. Therefore, we obtained twenty-five aortic specimens of heart donors during transplantation. The presence of TCs was detected in different layers of aortic tissue and characterized by immunofluorescence and transmission electron microscopy. Further, we cultivated and isolated TCs in highly differentiated form identified by positive staining for CD34 and c-kit. Aortic-derived TC was characterized by the expression of PDGFR-α, PDGFR-ß, CD29/integrin ß-1 and αSMA and the stem cell markers Nanog and KLF-4. Moreover, TC exosomes were isolated and characterized for soluble angiogenic factors by Western blot. CD34+ /c-kit+ TCs shed exosomes containing the soluble factors VEGF-A, KLF-4 and PDGF-A. In summary, TC occurs in the aortic wall. Correspondingly, exosomes, derived from aortic TCs, contain vasculogenesis-relevant proteins. Understanding the regulation of TC-mediated aortic remodelling may be a crucial step towards designing strategies to promote aortic repair and prevent adverse remodelling.

CD34+ Stromal Cells/Telocytes as a Source of Cancer-Associated Fibroblasts (CAFs) in Invasive Lobular Carcinoma of the Breast.

Several origins have been proposed for cancer-associated fibroblasts (CAFs), including resident CD34+ stromal cells/telocytes (CD34+SCs/TCs). The characteristics and arrangement of mammary CD34+SCs/TCs are well known and invasive lobular carcinoma of the breast (ILC) is one of the few malignant epithelial tumours with stromal cells that can express CD34 or αSMA, which could facilitate tracking these cells. Our objective is to assess whether tissue-resident CD34+SCs/TCs participate in the origin of CAFs in ILCs. For this purpose, using conventional and immunohistochemical procedures, we studied stromal cells in ILCs (n:42) and in normal breasts (n:6, also using electron microscopy). The results showed (a) the presence of anti-CD34+ or anti-αSMA+ stromal cells in varying proportion (from very rare in one of the markers to balanced) around nests/strands of neoplastic cells, (b) a similar arrangement and location of stromal cells in ILC to CD34+SCs/TCs in the normal breast, (c) both types of stromal cells coinciding around the same nest of neoplastic cells and (d) the coexpression of CD34 and αSMA in stromal cells in ILC. In conclusion, our findings support the hypothesis that resident CD34+SCs/TCs participate as an important source of CAFs in ILC. Further studies are required in this regard in other tumours.

Telocytes are major constituents of the angiogenic apparatus.

The current study investigated role of telocytes (TCs) in angiogenesis during embryonic development of quail using immunohistochemistry (IHC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The angiogenic apparatus consisted of TCs, endothelial cells, and macrophages. TCs were identified morphologically by their telopodes and podoms using TEM and SEM and immunohistochemically using CD34, and vascular endothelial growth factor (VEGF). TCs also expressed CD68. TCs formed a three-dimensional network and established direct contact with blood vessels, sprouting endothelial cells, and active macrophages, while exerting their effect through paracrine signaling. VEGF was also expressed by endothelial cells and macrophages. Matrix metalloproteinase-9 (MMP-9) was expressed by TCs, endothelial cells, and macrophages. In conclusion, the expression of VEGF by TCs, endothelial cells, and macrophages is required for the proliferation and migration of endothelial cells and vascular growth. The expression of MMP-9 by TCs, endothelial cells, and macrophages is essential for the degradation of extracellular matrix (ECM) components during neoangiogenesis. Macrophages may facilitate phagocytosis and elimination of the degraded ECM components.

Ultrastructural evidence for telocytes in equine tendon.

The three-dimensional ultrastructure of the tendon is complex. Two main cell types are classically supported: elongated tenocytes and ovoid tenoblasts. The existence of resident stem/progenitor cells in human and equine tendons has been demonstrated, but their location and relationship to tenoblasts and tenocytes remain unclear. Hence, in this work, we carried out an ultrastructural study of the equine superficial digital flexor tendon. Although the fine structure of tendons has been previously studied using electron microscopy, the presence of telocytes, a specific type of interstitial cell, has not been described thus far. We show the presence of telocytes in the equine inter-fascicular tendon matrix near blood vessels. These telocytes have characteristic telopodes, which are composed of alternating dilated portions (podoms) and thin segments (podomers). Additionally, we demonstrate the presence of the primary cilium in telocytes and its ability to release exosomes. The location of telocytes is similar to that of tendon stem cells. The telocyte-blood vessel proximity, the presence of primary immotile cilia and the release of exosomes could have special significance for tendon homeostasis.

Muscularis macrophages establish cell-to-cell contacts with telocytes/PDGFRα-positive cells and smooth muscle cells in the human and mouse gastrointestinal tract.

BACKGROUND AND AIM: Muscularis macrophages (MMs) not only mediate the innate immunity, but also functionally interact with cells important for gastrointestinal motility. The aim of this study was to determine the spatial relationship and types of contacts between the MMs and neighboring cells in the muscularis propria of human and mouse stomach, small intestine, and large intestine. METHODS: The distribution and morphology of MMs and their contacts with other cells were investigated by immunohistochemistry and transmission electron microscopy. KEY RESULTS: Immunohistochemistry showed variable shape and number of MMs according to their location in different portions of the muscle coat. By double labeling, a close association between MMs and neighboring cells, that is, neurons, smooth muscle cells, interstitial cells of Cajal (ICCs), telocytes (TCs)/PDGFRα-positive cells, was seen. Electron microscopy demonstrated that in the muscle layers of both animal species, MMs have similar ultrastructural features and have specialized cell-to-cell contacts with smooth muscle cells and TCs/PDGFRα-positive cells but not with ICCs and enteric neurons. CONCLUSION & INFERENCES: This study describes varying patterns of distribution of MMs between different regions of the gut, and reports the presence of distinct and extended cell-to-cell contacts between MMs and smooth muscle cells and between MMs and TCs/PDGFRα-positive cells. In contrast, MMs, although close to ICCs and nerve elements, did not make contact with them. These findings indicate specialized and variable roles for MMs in the modulation of gastrointestinal motility whose significance should be more closely investigated in normal and pathological conditions.

Fish telocytes and their relation to rodlet cells in ruby-red-fin shark (rainbow shark) Epalzeorhynchos frenatum (Teleostei: Cyprinidae).

Telocytes comprise the major constituents of the supportive interstitial framework within the various organs. They form a 3D network between different types of stromal and non-stromal cells, which makes them distinctively vital. We have previously explored the origin of the peculiar rodlet cells, especially on their differential stages in aquatic species. The current study aimed at highlighting the relation of telocytes with different rodlet stages. Samples of fish, olfactory organs, and gills were processed for semi thin sections, transmission electron microscopy, and immunohistochemistry. It was evident in the study that telocytes formed a 3D interstitial network, entrapping stem cells and differentiating rodlet cells, to establish direct contact with stem cells. Differentiated stem cells and rodlet progenitor cells, practically in the granular and transitional stages, also formed ultrastructure junctional modifications, by which nanostructures are formed to establish cell contact with telocytes. Telocytes in turn also connected with macrophage progenitor cells. Telocytes (TCs) expressed CD34, CD117, VEGF, and MMP-9. In conclusion, telocytes established direct contact with the stem and rodlet cells in various differential stages. Telocytes may vitally influence stem/progenitor cell differentiation, regulate rodlet cell function, and express MPP-9 that may regulate immune cells functions especially, including movement and migration ability.

Morphological and immunohistochemical phenotype of TCs in the intestinal bulb of Grass carp and their potential role in intestinal immunity.

The current study investigated telocytes (TCs) in the intestinal bulb of Grass carp using light microscopy (LM), Transmission electron microscopy (TEM), scanning electron microscopy, and immunohistochemistry (IHC). By LM, TCs were distinguished by the typical morphological features that had a cell body and telopodes using HE, toluidine blue, methylene blue, Marsland silver stain, Grimelius's silver nitrate, Giemsa, PAS, combined AB pH2,5/PAS, Crossmon's and Mallory triple trichrome, Van Gieson stains, Verhoeff's stain, Sudan black, osmic acid, performic acid with methylene blue and bromophenol blue. TCs were identified under the epithelium as an individual cell or formed a TCs sheath. They detected in the lamina propria, between muscle fibers, around the myenteric plexus and fibrous tissue. TCs acquired immunological features of endocrine cells that exhibited high affinity for silver stain, performic acid with methylene blue, Marsland stain, and immunohistochemical staining using chromogranin A. Sub epithelial TCs were closely related to the endocrine cells. TCs and their secretory activities were recognized using acridine orange. TCs were identified by IHC using CD34, CD117, S100-protein, desmin. TCs formed a3D network that established contact with macrophage, mast cells, dendritic cells, lymphocytes, smooth muscle fibers, fibroblast, Schwann cells and nerve fibers. In conclusion, the localization of TCs in relation to different types of immune cells indicated their potential role in the maintenance of intestinal immunity.