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

Abstract

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.

Morphological studies on the prehatching development of the glandular stomach of Japanese quails using light, electron, and fluorescent microscopy

“…The fixed specimens were dehydrated in an increasing graded alcohol series before being imbedded in an Epon-Araldite combination, as described by Abd-Elhafeez et al 86 , and as stated by Suvarna et al 81 . Karnovsky’s Fixative 87 was used to fix small sections of the specimens (2.0–3.0 mm length) at 4C overnight.…”

The telocytes relationship with satellite cells: Extracellular vesicles mediate the myotendinous junction remodeling

“…The TC are characterized by their restricted tissue microenvironments and were found in different species at the angiogenic apparatus (Soliman, 2021), in the cardiac muscle (Klein et al, 2021;Tao et al, 2016), lungs (Hussein & Mokhtar, 2018), eyes (Luesma et al, 2013), skin (Manole et al, 2022), liver (Liu et al, 2016), testis (Liu et al, 2019), female reproductive system (Varga & Klein, 2023), gastrointestinal environment (Aleksandrovych et al, 2022), cartilaginous tissue (Abd-Elhafeez et al, 2023), peripheral nervous system (Mirancea et al, 2022), skeletal muscle interstitium (Ravalli et al, 2021;Rosa et al, 2021;Squecco et al, 2021), and in the myotendinous junction (MTJ) extracellular matrix (Pimentel Neto et al, 2020) forming a cell niche.…”