Toward understanding the role of the interstitial tissue architects: Possible functions of telocytes in the male gonad

Telocytes represent a relatively recently discovered population of interstitial cells with a unique morphological structure that distinguishes them from other neighboring cells. Through their long protrusions extending from the cell body, telocytes create microenvironments via tissue compartmentalization and create homo- and hetero-cellular junctions. These establish a three-dimensional network enabling the maintenance of interstitial compartment homeostasis through regulation of extracellular matrix organization and activity, structural support, paracrine and juxtracrine communication, immunomodulation, immune surveillance, cell survival, and apoptosis. The presence of telocytes has also been confirmed in testicular interstitial tissue of many species of animals. The objective of this review is to summarize recent findings on telocytes in the male gonad, on which conclusions have been deduced that indicate the involvement of telocytes in maintaining the cytoarchitecture of the testicular interstitial tissue, in the processes of spermatogenesis and steroidogenesis, and photoperiod-mediated changes in the testes in seasonally reproductive animals.

The role of telocytes and miR-21-5p in tumorigenicity and metastasis of breast cancer stem cells

BACKGROUND

This study aims to investigate the roles of telocytes on the metastatic properties of breast cancer stem cells (CSCs), and to re-evaluate the effect of miR-21-5p expression on CSCs following the addition of telocytes.

METHODS AND RESULTS

Telocytes from human bone marrow mononuclear cells were isolated/characterised. This was followed by the isolation/characterisation of CSCs from the MDA-MB-231. miR-21-5p was both overexpressed/inhibited in CSCs. Through co-culture studies, EMT transition and oncogenic properties of CSCs were investigated by analysing changes in ALDH1 and vimentin protein levels as well as changes in the ABCC11, SNAI1, LZTFL1, Oct 3/4, E- and N-cadherin gene expression levels. With the inhibition of miR-21-5p, significant increases in LZTFL and ABCC11 were observed with the addition of telocytes. The expression of the LZTFL gene, which decreased with the overexpression of miR-21-5p, increased in CSCs after co-culture with telocytes. While an increase expression of ABCC11, SNAI1, N-Cadherin, vimentin and ALDH was observed in CSCs after overexpression of miR-21-5p, significant decreases in these expressions were observed after co-culture with telocyte.

CONCLUSIONS

In our study, by gene/protein level analysis we demonstrated that telocytes may have the potential to reduce cancer metastasis through miR-21-5p in breast cancer progression and reduce EMT transition.

Is bladder outlet obstruction rat model to induce overactive bladder (OAB) has similarity to human OAB? Research on the events in smooth muscle, collagen, interstitial cell and telocyte distribution

BACKGROUND

Cellular and cytoskeletal events of overactive bladder (OAB) have not been sufficiently explored in human bladder due to different limitations. Bladder outlet obstruction (BOO) had been induced in different animal models with different methods to induce (OAB). Similarity of the animal models of BOO to the human OAB is postulated but has not been confirmed. The interstitial cells of Cajal (ICCs), and telocytes (TCs) are an important players in smooth muscles conductivity, they had not been well investigated in the previous BOO models. Objectives are to investigate the morphological pattern of cellular, cytoskeleton and telocytes distribution in BOO rat model and to match the events in two time periods and compare it to the findings in real-world human OAB.

METHODS

Female Sprague-Dawley rats (Rattus norvegicus) were randomly divided into: sham (n = 10), BOO 6 W (n = 10), BOO 8 W (n = 10). Operative procedure to Induce BOO was done under anesthesia with intraperitoneal Ketamine administration. The Effect of induction of BOO was evaluated after 6 and 8 weeks. The rats were anesthetized, and the urinary bladder was removed, while the rat was unconscious under anaesthesia it was transferred to the inhalation anaesthesia cage for euthanasia, rats were sacrificed under light anesthesia using isoflurane. Care of animals, surgical procedure, and euthanasia adhered to Guide for the Care and Use of Laboratory Animals, and AVMA Guidelines for the Euthanasia of Animals. The retrieved bladder was processed for examination with histopathology, immunohistochemistry (IHC), and transmission electron microscopy (EM).

RESULTS

Histological examination of the bladder shows thinner urothelium, condensation of collagen between muscle bundles. IHC with c-kit shows the excess distribution of ICCs between smooth muscle bundles. EM shows frequent distribution of TCs that were situated between collagen fibers. Finings in BOO 6 W group and BOO 8 W group were comparable.

CONCLUSION

The animal model study demonstrated increased collagen/ smooth muscle ratio, high intensity of ICCs and presence of TCs. Findings show that a minimally invasive procedure to induce BOO in rats had resulted in an OAB that has morphological changes that were stable in 6 & 8 weeks. We demonstrated the distribution of TCs and ICCs in the rat animal model and defined them. The population of TCs in the BOO rat model is described for the first time, suggests that the TCs and ICCs may contribute to the pathophysiology of OAB. Similarity of animal model to human events OAB was demonstrated. These findings warrant further study to define the role of TCs in OAB.

CLINICAL TRIAL REGISTRY

The study does not require a clinical trial registration; it is an experimental animal study in basic science and does not include human subjects.

Ultrastructural evidence of telocytes in the embryonic chick heart

The cardiac telocyte (TC) is a novel interstitial cell type with a unique ultrastructure and great potential in therapy. The present study examined its presence in the heart of chicken embryos ageing 7-15 days old (Hamburger-Hamilton [HH] stages 31-41) using transmission electron microscopy. TCs were identified across all stages in the atrial and ventricular myocardium, close to maturing cardiomyocytes, blood vessels and lymphatics. Early-stage TCs have immature features resembling mesenchymal cells. Late-stage TCs were distinct, possessing the cytoplasmic prolongations termed telopodes (Tps), which are very long and thin, usually 1-3 in number, and display a moniliform appearance and have an average thickness below 0.2 μm. TCs residing in the epicardium and endocardium were also detected. In the subepicardium near developing coronary vessels, they were localized in the cardiac stem cell niches, coexisting with cardiac stem cells and cardiomyocyte progenitors. Electron-dense structures and the release of extracellular vesicles were observed between embryonic TCs and surrounding structures, suggesting roles in intercellular communication, cardiomyocyte differentiation and maturation, angiogenesis, and stem cell nursing and guidance.

Morphological changes in intraepithelial and stromal telocytes in Cyprinus carpio in response to salinity stress

Telocytes establish connections and communicate with various types of cells and structures. Few experimental studies have been performed on telocytes. In this study, we investigated the effect of salinity stress on telocytes in relation to osmoregulatory, immune, and stem cells. After exposing the common carp to 0.2 (control), 6, 10, or 14 ppt salinity, we extracted and fixed gill samples in glutaraldehyde, processed and embedded the samples in resin, and prepared semi-thin and ultrathin sections. Two types of telocytes were identified: intraepithelial and stromal telocytes. Intraepithelial telocytes were found to form part of the cellular lining of the lymphatic space and shed secretory vesicles into this space. Stromal telocytes were observed to shed their secretory vesicles into the secondary circulatory vessels. Both intraepithelial and stromal telocytes were enlarged and exhibited increased secretory activities as salinity increased. They exerted their effects via direct contact and paracrine signaling. The following changes were observed in samples from fish exposed to high salinity levels: chloride cells underwent hypertrophy, and their mitochondria became cigar-shaped; pavement cells were enlarged, and their micro-ridges became thin and elongated; stromal telocytes established contact with stem cells and skeletal myoblasts; skeletal muscle cells underwent hypertrophy; and macrophages and rodlet cells increased in number. In conclusion, our findings indicate that intraepithelial and stromal telocytes respond to salinity stress by activating cellular signaling and that they play major roles in osmoregulation, immunity, and regeneration.

A cellular regulator of the niche: telocyte

Interstitial cells are present in the environment of stem cells in order to increase stem cell proliferation and differentiation and they are important to increase the efficiency of their transplantation. Telocytes (TCs) play an important role both in the preservation of tissue organ integrity and in the pathophysiology of many diseases, especially cancer. They make homo- or heterocellular contacts to form the structure of 3D network through their telopodes and deliver signaling molecules via a juxtacrine and/or paracrine association by budding shed vesicles into the vascular, nervous and endocrine systems. During this interaction, along with organelles, mRNA, microRNA, long non-coding RNA, and genomic DNA are transferred. This review article not only specifies the properties of TCs and their roles in the tissue organ microenvironment but also gives information about the factors that play a role in the transport of epigenetic information by TCs.

Cellular Evidence for Telocytes Mediating Electroacupuncture to Ameliorate Obesity in Mice

Electroacupuncture has been generally applied to target obesity, the principle of which is based on the meridian in traditional Chinese medicine. Although Telocytes (TCs) have been reported as the potential essence of meridians, their specific role in the electroacupuncture treatment of obesity remains unclear. Thus, we investigated the cellular evidence for TC-mediated electroacupuncture to alleviate obesity. Mice were divided into three groups as follows: electroacupuncture group (EA), control group (CG), and normal group (NG). The present study showed that the weight of perirenal white adipose tissue (rWAT), the serum level of total cholesterol, and the low-density lipoprotein cholesterol were all significantly decreased after electroacupuncture. Ultrastructurally, the prolongations (telopodes, Tps) of TCs were in direct contact with adipocytes, and lipid droplets were distributed on the surface of Tps. The proportions of double-positive fluorescent areas of TCs (CD34 and PDGFRα) were significantly elevated with concomitant elongated Tps in EA mice, as compared to those in CG mice. The expression of Cx43 and CD63 (gap junction and exosome markers) was significantly enhanced. These characteristics facilitated the transmission of electroacupuncture stimulation from skin to rWAT. We conclude that electroacupuncture relieved obesity by activating TCs morphologically, upregulating the gap junctions between TCs, and increasing the exosomes around TCs.

Morphology of migrating telocytes and their potential role in stem cell differentiation during cartilage development in catfish (Clarias gariepinus)

Telocytes (TCs) are present in a broad range of species and regulate processes including homeostasis, tissue regeneration and immunosurveillance. This novel study describes the morphological features of migrating TCs and their role during cartilage development within the air-breathing organ in Clarias gariepinus, the African sharptooth catfish. Light microscopy (LM), transmission electron microscopy (TEM), and immunohistochemistry (IHC) were used to examine the TCs. TCs had a cell body and telopodes which formed 3D networks in the cartilage canals and extended their telopodes to become the foremost cellular elements penetrating the cartilage matrix. The TCs were also rich in lysosomes that secreted products to the extracellular matrix (ECM). In addition, TCs formed a homocellular synaptic-like structure that had a synaptic cleft, and the presynaptic portion consisted of a slightly expanded terminal of the telopodes which contained intermediate filaments and secretory vesicles. Gap junctions were also identified between TCs, which also connected to mesenchymal stem cells, differentiating chondrogenic cells, macrophages, apoptotic cells, and endothelial cells. In addition to describing the basic morphology of TCs, the current study also investigated migrating TCs. The TC telopodes acquired an irregular contour when migrating rather than exhibiting an extended profile. Migrating TCs additionally had ill-defined cell bodies, condensed chromatin, thickened telopodes, and podoms which were closely attached to the cell body. The TCs also expressed markers for MMP-9, CD117, CD34 and RhoA. In conclusion, TCs may play multiple roles during development and maturation, including promoting angiogenesis, cell migration, and regulating stem cell differentiation. RESEARCH HIGHLIGHTS: Clarias gariepinus telocytes form 3D networks, extend their telopodes and contain lysosomes. Telocytes form a homocellular synaptic-like structure including clefts and a slightly expanded terminal of the telopodes which contains intermediate filaments and secretory vesicles. Gap junctions form between telocytes, which also connect to mesenchymal stem cells, differentiating chondrogenic cells, macrophages, apoptotic cells, and endothelial cells. Migrating telocytes were discovered which had ill-defined cell bodies, condensed chromatin, thickened telopodes exhibiting irregular contours, and podoms which were closely attached to the cell body.

Regulatory roles of Osteopontin in lung epithelial inflammation and epithelial-telocyte interaction

BACKGROUND

Lung epithelial cells play important roles in lung inflammation and injury, although mechanisms remain unclear. Osteopontin (OPN) has essential roles in epithelial damage and repair and in lung cancer biological behaviours. Telocyte (TC) is a type of interstitial cell that interacts with epithelial cells to alleviate acute inflammation and lung injury. The present studies aim at exploring potential mechanisms by which OPN regulates the epithelial origin lung inflammation and the interaction of epithelial cells with TCs in acute and chronic lung injury.

METHODS

The lung disease specificity of OPN and epithelial inflammation were defined by bioinformatics. We evaluated the regulatory roles of OPN in OPN-knockdown or over-expressed bronchial epithelia (HBEs) challenged with cigarette smoke extracts (CSE) or in animals with genome OPN knockout (gKO) or lung conditional OPN knockout (cKO). Acute lung injury and chronic obstructive pulmonary disease (COPD) were induced by smoking or lipopolysaccharide (LPS). Effects of OPN on PI3K subunits and ERK were assessed using the inhibitors. Spatialization and distribution of OPN, OPN-positive epithelial subtypes, and TCs were defined by spatial transcriptomics. The interaction between HBEs and TCs was assayed by the co-culture system.

RESULTS

Levels of OPN expression increased in smokers, smokers with COPD, and smokers with COPD and lung cancer, as compared with healthy nonsmokers. LPS and/or CSE induced over-production of cytokines from HBEs, dependent upon the dysfunction of OPN. The severity of lung inflammation and injury was significantly lower in OPN-gKO or OPN-cKO mice. HBEs transferred with OPN enhanced the expression of phosphoinositide 3-kinase (PI3K)CA/p110α, PIK3CB/p110β, PIK3CD/p110δ, PIK3CG/p110γ, PIK3R1, PIK3R2 or PIK3R3. Spatial locations of OPN and OPN-positive epithelial subtypes showed the tight contact of airway epithelia and TCs. Epithelial OPN regulated the epithelial communication with TCs, and the down-regulation of OPN induced more alterations in transcriptomic profiles than the up-regulation.

CONCLUSION

Our data evidenced that OPN regulated lung epithelial inflammation, injury, and cell communication between epithelium and TCs in acute and chronic lung injury. The conditional control of lung epithelial OPN may be an alternative for preventing and treating epithelial-origin lung inflammation and injury.

Telocytes/CD34+ Stromal Cells in the Normal, Hyperplastic, and Adenomatous Human Parathyroid Glands

Telocytes/CD34+ stromal cells (TCs/CD34+ SCs) have been studied in numerous organs and tissues, but their presence and characteristics in the parathyroid glands have not been explored. Using immunological and ultrastructural procedures, we assess the location, arrangement, and behavior of TCs/CD34+ SCs in normal human parathyroids, during their development and in their most frequent pathologic conditions. In normal parathyroids, TCs/CD34+ SCs show a small somatic body and long thin processes with a moniliform aspect, form labyrinthine systems, connect other neighboring TCs/CD34+ SCs, vessels, adipocytes, and parenchymal cells directly or by extracellular vesicles, and associate with collagen I. TCs/CD34+ SCs and collagen I are absent around vessels and adipocytes within parenchymal clusters. In developing parathyroids, TCs/CD34+ SC surround small parenchymal nests and adipocytes. In hyperplastic parathyroids, TCs/CD34+ SCs are prominent in some thickened internodular septa and surround small extraglandular parenchymal cell nests. TCs/CD34+ SCs are present in delimiting regions with compressed parathyroids and their capsule in adenomas but absent in most adenomatous tissue. In conclusion, TCs/CD34+ SCs are an important cellular component in the human parathyroid stroma, except around vessels within parenchymal nests. They show typical characteristics, including those of connecting cells, are present in developing parathyroids, and participate in the most frequent parathyroid pathology, including hyperplastic and adenomatous parathyroids.

The Cellular Mechanism of Acupuncture for Ulcerative Colitis based on the Communication of Telocytes

Acupuncture can ameliorate or treat diseases according to the meridian theory in traditional Chinese medicine (TCM); however, its mechanism has not been scientifically clarified. On the other hand, telocytes (TCs) are morphologically in accordance with the meridian system, which needs further cytological investigations and acupuncture confirmation. The present study showed that acupuncture could activate TCs in several ways, alleviating rabbit ulcerative colitis. TCs could cytologically communicate the acupoints, the acupuncture sites in skin with their corresponding large intestine by TC homo-cellular junctions, exosomes around TCs, and TC-mediated nerves or blood vessels. TCs expressed transient receptor potential vanilloid type 4, the mechanosensitive channel protein that can transduce the mechanical stimulation of acupuncture into biochemical signals transferring along the extremely thin and long TCs. Collectively, a cellular mechanism diagram of acupuncture was concluded based on TC characteristics. Those results also confirmed the viewpoint that TCs were the key cells of meridian essence in TCM.

Distribution and Ultrastructural Features of Telocytes in the Pars Distalis of the Rat Pituitary Gland

Telocytes (TCs), a novel type of interstitial cells, are characterized by their smaller cellular body and extremely long, thin processes which are called telopodes (Tps). They have been described in multiple organs from diverse animals. Currently, the existence of TCs in rat pars distalis (PD) has remained unexplored. This investigation was undertaken to visualize the distribution and structural features of TCs in the PD using immunofluorescence (IF) and further validated by transmission electron microscopy (TEM). HE staining revealed the presence of interstitial cells in the peri-sinusoidal vessels spaces of the PD. Using IF, CD34/vimentin double-positive interstitial cells were identified as TCs in accordance with identification standards. TEM further verified the presence of TCs based on their unique ultrastructural features. TCs exhibited communication structures including cell connections and extracellular vesicles (EVs). Interestingly, TCs were in close proximity to the nerves. Most importantly, Tps extended toward the nerves, blood vessels, and glandular cells. TCs could be the structural foundation of a third regulatory system in rat PD according to the tight connections of TCs with sinusoid vessels, glandular cells, EVs and most crucially the nerves. Taken together, these morphological and structural findings demonstrate that TCs are vital components of the rat PD.

The Role of Telocytes and Telocyte-Derived Exosomes in the Development of Thoracic Aortic Aneurysm

A hallmark of thoracic aortic aneurysms (TAA) is the degenerative remodeling of aortic wall, which leads to progressive aortic dilatation and resulting in an increased risk for aortic dissection or rupture. Telocytes (TCs), a distinct type of interstitial cells described in many tissues and organs, were recently observed in the aortic wall, and studies showed the potential regulation of smooth muscle cell (SMC) homeostasis by TC-released shed vesicles. The purpose of the present work was to study the functions of TCs in medial degeneration of TAA. During aneurysmal formation an increase of aortic TCs was identified in human surgical specimens of TAA-patients, compared to healthy thoracic aortic (HTA)-tissue. We found the presence of epithelial progenitor cells in the adventitial layer, which showed increased infiltration in TAA samples. For functional analysis, HTA- and TAA-telocytes were isolated, characterized, and compared by their protein levels, mRNA- and miRNA-expression profiles. We detected TC and TC-released exosomes near SMCs. TAA-TC-exosomes showed a significant increase of the SMC-related dedifferentiation markers KLF-4-, VEGF-A-, and PDGF-A-protein levels, as well as miRNA-expression levels of miR-146a, miR-221 and miR-222. SMCs treated with TAA-TC-exosomes developed a dedifferentiation-phenotype. In conclusion, the study shows for the first time that TCs are involved in development of TAA and could play a crucial role in SMC phenotype switching by release of extracellular vesicles.

Pulmonary Guardians and Special Regulatory Devices in the Lung of Nile Monitor Lizard (Varanus niloticus) with Special Attention to the Communication Between Telocyte, Pericyte, and Immune Cells

Monitor lizards are acclimatized to a variety of environments. Most of the monitor species are terrestrial, although there are arboreal and semiaquatic monitors. Such accommodation requires unique cellular structure and regulatory devices in various organs, particularly their lungs. This study aimed to report the pulmonary guardians and special regulatory devices that may guard and promote the function of the lungs of the Nile monitor lizards (Varanus niloticus). Specially structured vessels were recorded in the pulmonary tissue involving atypical glomus vessels, vessels with variable wall thickness, and a venule with specialized internal elastic membrane. Moreover, numerous lung resident guardians could be identified including both alveolar and interstitial macrophages, dendritic cells, mast cells, and B- and T-lymphocytes. Pericytes were demonstrated surrounding the capillary endothelium with a characteristic direct hetero-cellular junction with telocytes. Telocytes established a microenvironment through an indirect hetero-cellular junction with the interstitial macrophage, dendritic cells, and pneumocyte type II. Collectively, these data indicate a significant role played by the specially structured vessels and the resident immune cells in guarding the pulmonary tissue of the Nile monitor lizards and promoting its function. Telocytes are suggested to play a key role in angiogenesis and cellular communication to promote the function of the immune cells.

Role of telocytes in the pathogenesis of ectopic pregnancy

OBJECTIVE

The aim of this study is to investigate the effect of telocytes on tubal motility in ectopic pregnancies.

PATIENTS AND METHODS

This study included patients with ectopic pregnancy (EP) (n=10) and control patients (n=10) (partial salpingectomy for contraception). Immunohistochemical staining for c-Kit, vimentin, CD34 and S100A was performed to quantify telocytes in the mucosa, muscular layer and serosa of fallopian tubes of control and EP group. Spontaneous and KCl- (80 mM) induced contraction and cumulative progesterone dose-relaxation (10-11-10-5 M) and cumulative oxytocin dose-contraction (10-10-10-4 M) responses were recorded.

RESULTS

The groups were comparable in terms of age, gravida, parity, delivery type and gestational week (p>0.05). The homogenous distribution of telocytes in the mucosa and muscular layers of the control group, changed to heterogeneous localization the EP group. Immunohistochemical staining with vimentin, S100A, c-Kit and CD34, revealed increased telocyte counts in the muscular layer and serosa of the tubal tissues of EP. The frequency of the spontaneous contractions was higher in the control group (p<0.001); contrarily, the amplitude of the contractions was higher in ectopic pregnancies (p<0.001). Although the cumulative oxytocin dose-contraction curves were similar at all concentrations (p>0.05), the cumulative progesterone dose-relaxation curves exhibited higher relaxation response in the EP group at all concentrations (p<0.001).

CONCLUSIONS

Increased telocyte count in the fallopian tube may decrease tubal motility and may affect the transfer of the blastocyst to the uterus and possibly contribute to the pathogenesis of EP.

Telocytes and their structural relationships with surrounding cell types in the skin of silky fowl by immunohistochemistrical, transmission electron microscopical and morphometric analysis

Telocytes (TCs), a novel type of interstitial cells, were identified in various animals. Since TCs have not observed in avian skin, hence, we carried out immunohistochemistrical and transmission electron microscopical studies in the skin of the silky fowl to investigate the TCs. TCs appear as CD34, c-Kit, and PDGFRα immunopositive. The elongated TCs with 2 long and thin telopodes (Tps) are located in the dermis. Generally, a TC possesses a fusiform, ovoid and polygonal cell body with 2 Tps (lengths = 5.27-21.85 μm), which are uneven in thickness including thick sections - podoms (diameters = 0.40-0.47 μm) and thin sections - podomers (diameters = 0.03-0.04 μm). TCs/Tps are observed frequently in close proximity to neighboring cell types/structures, such as adipocytes, collagen fibers, and capillaries. Under a magnified field, homocellular TCs/Tps contacts are observed through gap junctions (distances = 0.01-0.05 μm), whereas some of TCs/Tps have heterocellular close contacts by point contacts with surrounding cells, including stem cells and melanocytes. The multivisicular bodies, especially exosomes (diameters = 0.09-0.23 μm) releasing from TCs/Tps are observed in close proximity to TCs/Tps. Our results illustrated that the novel type of interstitial cells - TCs are present in the dermis of the silky fowl, and they have special structural relationships with surrounding cell types. The study provides histological evidence for TCs involvement in intercellular communication, skin regeneration, and pigmentogenesis in avian skin.

Telocytes in rat lungs: an essential pool of cells or not?

B a c k g r o u n d: The histology of the lung includes a variety of cell types. Fibrosis is a universal process, occurring in the skin, intestine, heart, muscles, kidney, blood vessels, liver, and also the lungs. Telocytes are a type of cells with a wide range of properties, which were previously described in healthy and disease-affected organs of human and animal organisms. A i m: This study aimed to identify telocytes in the lungs of rats and discuss their possible role in the development of pulmonary fibrosis. M e t h o d s: Tissue samples were taken from a group of ten male Wistar rats. Further histological and immunohistochemical analysis was performed. Double immunolabeling for c-kit, vimentin, CD34, and PDGFRα has revealed telocytes in the lungs. R e s u l t s: In all tissue samples, telocytes have been identified (in the area of interalveolar septa, close to blood vessels, and between the airway epithelium). C o n c l u s i o n: Telocytes might be directly and indirectly (through contact with stem cells, secretomes, and reduction in number) involved in the development of pulmonary fibrosis. The heterogeneity of the telocyte population in different pathologies and their subtypes, as well as their tendency to be common stress their important role in pathological physiology.

Anatomical, Histological, and Electron Microscopic Structures of Syrinx in Male Budgerigars (Melopsittacus undulatus)

The syrinx is the main source for phonation in birds, its function is analogous to the mammalian larynx. Birds have both a larynx and a syrinx, but they use only the latter to vocalize. The objective of this work to give a detailed description of the anatomical, histological, and ultrastructural of syrinx in male budgerigars as a model of a passerine bird. The syrinx in the current study was to be found as a tracheobronchial type, it consists of cranial (tympanum) part and caudal (bronchosyringeal) part and, additionally, there are lateral vibrating membranes. The tympanum is formed of the last six tracheal rings, histologically its lamina epithelialis is a pseudostratified ciliated columnar epithelium with goblet cells and interrupted by intraepithelial glands. The secretory acini appear oval and lined by pyramidal secretory cells. The lamina propria–submucosa contain numerous blood capillaries, immune cells, and telocytes (TCs). The electron microscopic examination revealed numerous blood capillaries surrounded by fibroblasts and numerous immune cells, including mast cells and wandering leukocytes, within the tympanum mucosa. Hence, this study provides a detailed knowledge about the syrinx in male budgerigars.

Tissue Micro-channels Formed by Collagen Fibers and their Internal Components: Cellular Evidence of Proposed Meridian Conduits in Vertebrate Skin

In order to clarify fine structures of the hypothetical meridian conduits of Chinese traditional medicine (CTM) in the skin, the present study used light and transmission electron microscopy to examine fasciae in different vertebrate species. Collagen fiber bundles and layers were arranged in a crisscross pattern, which developed into a special tissue micro-channel (TMC) network, in a manner that was analogs to the proposed skin meridian conduits. It was further revealed that tissue fluid in lateral TMC branches drained into wide longitudinal channels, which were distinctly different from lymphatic capillary. Mast cells, macrophages, and extracellular vesicles such as ectosomes and exosomes were distributed around telocytes (TCs) and their long processes (Telopodes, Tps) within the TMC. Cell junctions between TCs developed, which could enable the communication between contiguous but distant Tps. On the other hand, winding free Tps without cell junctions were also uncovered inside the TMC. Tissue fluid, cell junctions of TCs, mast cells, macrophages, and extracellular vesicles within the TMC corresponded to the circulating "" ("Qi-Xue", i.e., information, message, and energy) of meridian conduits at the cytological level. These results could provide morphological evidence for the hypothesis that "meridians are the conduit for Qi-Xue circulation" in CTM.

Immunohistochemical evaluation of Cajal-like cells and Caveolin-1 levels at ureteropelvic junction obstruction

OBJECTIVE

To compare c-kit-positive interstitial Cajal-like cells (ICC) and Caveolin-1 protein levels as a pacemaker and signaling molecules, on ureteropelvic junction (UPJ) specimens, between two groups of pediatric patients with and without ureteropelvic junction obstruction (UPJO).

METHODS

We evaluated the UPJ specimens of 45 pediatric patients operated between 2005- 2012 retrospectively. Group 1 included 37 patients who underwent dismembered pyeloplasty due to UPJO. Eight patients underwent nephrectomy by the other reasons (renal tumor, trauma etc) and had normal UPJ were accepted as Group 2. The specimens were examined immunohistochemically with CD117 and Caveolin-1 antibody. According to the total number of ICC; 0-5 cells were accepted as a few (1), 610 cells as moderate (2), and > 10 as many (3). According to the staining intensity of Caveolin-1 at muscle tissue, a subjective evaluation was performed as; mild staining (1), moderate staining (2) and strong staining (3).

RESULTS

The mean value of ICC distribution was calculated 1.37 ± 0.54 in Group 1 and 2.13 ± 0.64 in Group 2 (p = 0.003), and the median value of ICC distribution was found 1 [1-3] in Group 1 and 2 [1-3] in Group 2 (p = 0.008). Median values for the intensity of staining with Caveolin-1 were found 2 [1-3] in the Group 1, and 2.5 [2-3] in the Group 2 (p = 0.025).

CONCLUSIONS

A decrease in ICC and Caveolin-1 levels support that there may be a relationship between ICC and Caveolin-1 for UPJO associated with signal transduction and peristalsis in urinary system.

Telocytes in the female reproductive system: An overview of up-to-date knowledge

Telocytes are emerging cell population localized in the stroma of numerous organs, characterized by a distinctive morphology - small cell body with very long, slender prolongations, termed telopodes. Those cells can be found in the whole female reproductive system: in the vagina, uterus, oviducts and ovaries, mammary glands and also in the placenta. In our review, we aim at complete and transparent revision of the current knowledge of telocytes' localization and function, enriched by the analysis of the possible future direction of development of their clinical applications. The function of telocytes in the reproductive system has not been fully elucidated yet; however, many researchers point at their role in the regulation of local microenvironment, myogenic contractile mechanism, bioelectrical signaling, immunomodulation and regulation of blood flow. Additionally, previous research suggests that telocytes might act as sex hormone level sensors and are connected with pregnancy maintenance. As the morphology and number of those cells change under pathological conditions, such as pre-eclampsia, endometriosis and ovarian failure, there is a chance that they may contribute to therapy of abovementioned conditions. The impact of telocytes on stem cells and angiogenesis has been proven in many organs, and may be useful in regenerative medicine of the female reproductive system. A recently found connection between the proliferation rate of breast cancer cells and stromal cells like telocytes might be a step forward to the management of mammary gland neoplasms.