The presence of a persistent median artery (PMA) has been implicated in the development of compression neuropathies and surgical complications. Due to the large variability in the prevalence of the PMA and its subtypes in the literature, more awareness of its anatomy is needed. The aim of our meta-analysis was to find the pooled prevalence of the antebrachial and palmar persistent median arteries. An extensive search through the major databases was performed to identify all articles and references matching our inclusion criteria. The extracted data included methods of investigation, prevalence of the PMA, anatomical subtype (antebrachial, palmar), side, sex, laterality, and ethnicity. A total of 64 studies (n = 10,394 hands) were included in this meta-analysis. An antebrachial pattern was revealed to be more prevalent than a palmar pattern (34.0% vs. 8.6%). A palmar PMA was reported in 2.6% of patients undergoing surgery for carpal tunnel syndrome when compared to cadaveric studies of adult patients in which the prevalence was 8.6%. Both patterns of PMA are prevalent in a considerable portion of the general population. As the estimated prevalence of the PMA was found to be significantly lower in patients undergoing surgery for carpal tunnel syndrome than those reported in cadaveric studies, its etiological contribution to carpal tunnel syndrome is questionable. Surgeons operating on the forearm and carpal tunnel should understand the anatomy and surgical implications of the PMA and its anatomical patterns.

Purpose: The accessory parotid gland is a collection of salivary tissue separate from the main parotid gland. When present, it may complicate parotidectomies, promote parotitis, and serve as a potential site for benign and malignant lesions to arise. The aim of this study was to provide a comprehensive and current overview of the anatomy of the accessory parotid gland, as there is a wide discrepancy in the literature regarding its prevalence. Materials and Methods: The authors conducted a search in PubMed, Embase, ScienceDirect, Web of Science, SciELO, BIOSIS, Current Content Connect, Korean Journal Database, and Russian Citation Index to identify all studies which reported relevant data on the accessory, with no date or language restrictions applied. Data on prevalence, side of occurrence, and sex dimorphism of the accessory parotid gland were extracted and pooled into a meta-analysis. Results: A total of 13 articles (n = 3115 subjects) were included in the study. The results revealed that the overall pooled prevalence of an accessory parotid gland was 32.1% (95% confidence interval: 21.2–44.0). It was more prevalent in cadaveric studies (35.8%) than in computed tomography studies (21.5%), had a higher prevalence in Asia (33.8%) as compared to North America (23.5%), and when present, it was most often found as an unilateral structure (77.8%). Conclusions: With respect to the findings presented, the accessory parotid gland may be considered an anatomical variation likely to encounter in the population. More anatomical studies on the structure and its prevalence are needed, in all regions of the world, to provide a representative global overview.

Aortic valve interstitial cells (VICs) constitute a heterogeneous population involved in the maintenance of unique valvular architecture, ensuring proper hemodynamic function but also engaged in valve degeneration. Recently, cells similar to telocytes/interstitial Cajal-like cells described in various organs were found in heart valves. The aim of this study was to examine the density, distribution, and spatial organization of a VIC subset co-expressing CD34 and PDGFRα in normal aortic valves and to investigate if these cells are associated with the occurrence of early signs of valve calcific remodeling. We examined 28 human aortic valves obtained upon autopsy. General valve morphology and the early signs of degeneration were assessed histochemically. The studied VICs were identified by immunofluorescence (CD34, PDGFRα, vimentin), and their number in standardized parts and layers of the valves was evaluated. In order to show the complex three-dimensional structure of CD34+/PDGFRα+ VICs, whole-mount specimens were imaged by confocal microscopy, and subsequently rendered using the Imaris (Bitplane AG, Zürich, Switzerland) software. CD34+/PDGFRα+ VICs were found in all examined valves, showing significant differences in the number, distribution within valve tissue, spatial organization, and morphology (spherical/oval without projections; numerous short projections; long, branching, occasionally moniliform projections). Such a complex morphology was associated with the younger age of the subjects, and these VICs were more frequent in the spongiosa layer of the valve. Both the number and percentage of CD34+/PDGFRα+ VICs were inversely correlated with the age of the subjects. Valves with histochemical signs of early calcification contained a lower number of CD34+/PDGFRα+ cells. They were less numerous in proximal parts of the cusps, i.e., areas prone to calcification. The results suggest that normal aortic valves contain a subpopulation of CD34+/PDGFRα+ VICs, which might be involved in the maintenance of local microenvironment resisting to pathologic remodeling. Their reduced number in older age could limit the self-regenerative properties of the valve stroma.

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