Mitochondria-Rich Cells: A Novel Type of Concealed Cell in the Small Intestine of Chinese Soft-Shelled Turtles (Pelodiscus Sinensis)

Abstract

Although some studies have been conducted over the past few decades, the existence of mitochondria-rich cells (MRCs) in reptiles is still obscure. This is the first study to uncover the presence of MRCs in the small intestine of Chinese soft-shelled turtles. In this study, we investigated the ultrastructural characteristics of MRCs and the secretion of different ion transport proteins in the small intestine of Pelodiscus sinensis. Transmission electron microscopy revealed that the ultrastructural features of MRCs are clearly different from those of other cells. The cytoplasmic density of MRCs was higher than absorptive epithelial cells (AECs) and goblet cells (GCs). MRCs possessed abundant heterogeneous mitochondria and an extensive tubular system in the cytoplasm, however, the AECs and GCs completely lacked a tubular system. Statistical analysis showed that the diameter and quantification of mitochondria were highly significant in MRCs. Mitochondrial vacuolization and despoiled mitochondria were closely associated with autophagosomes in MRCs. The multivesicular bodies (MVBs) and the exosome secretion pathway were observed in MRCs. Immunohistochemical staining of ion transport proteins indicated positive immunoreactivity of Na+/K+_ATPase (NKA) and Na+/K+/2Cl− cotransporter (NKCC) at the basal region of the mucosal surface. Likewise, the immunofluorescence staining results showed a strong positive localization of NKA, NKCC, and carbonic anhydrase (CA) at the basal and apical region of the mucosal surface of small intestine. Our findings suggest that MRCs provide support and regulate cellular ions for intestinal homeostasis and provide energy for cellular quality control in intestine.

Elucidating Methods for Isolation and Quantification of Exosomes: A Review

“…EVs from human milk were also quantified using SEM and it was observed that the size of these nanovesicles was in the range between 50 and 350 nm [ 108 ]. Transmission electron microscopy (TEM) was employed for the purpose of quantification and characterization of mitochondria-rich cells that provide cellular ions for intestinal homeostasis to study and understand its optimal regulation [ 109 ]. A cryo-transmission electron microscope was used to identify and characterize the heterogeneous populations of urinary extracellular vesicles from low centrifugation pellets [ 110 ].…”

Osmoregulatory and immunological role of new canceled cells: Mitochondrial rich cells and its future perspective: A concise review

“…Before this, no one have detected the immunological role of MRCs. It was the first time, the detection of this novel immunological advance network of MRCs, although Vistro and Bai et al, observed that MRCs secreted exosomes‐MVBs pathway in the small intestine of turtle and fish (Figure 2) (Ali Vistro et al, 2019; Bai, Shi, et al, 2019). As we know the intestine is not only a site for nutritional digestion and absorption (Shi et al, 2020), but also plays an important role in immunology via the production and secretion of exosomal‐MVBs (Ayyar & Moss, 2021).…”

“…Mitochondrial‐rich cells (MRCs) are typical type of epithelial cells, morphologically these cells are totally different from other epithelial cells (Figure 1). These cells mainly observed in the gills, kidney, small intestine, and yolk‐sac membrane of fish (Esaki et al, 2009; Jonz & Nurse, 2006; Lin & Sung, 2003), as well as in the lower intestine of avians and reptiles (Ali Vistro et al, 2019; Elbrønd et al, 2004; Vistro, Tarique, et al, 2019). Abundant mitochondria with a high electron density and an abundance of tubular systems in the cytoplasm are morphological characteristics of these cells (Vistro, Tarique, et al, 2019).…”