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Emperipolesis is a cell-within-cell phenomenon distinct from phagocytosis more often described in Rosai-Dorfman disease, where usually lymphocytes or other bone marrow cells (plasma cells, erythroblasts or neutrophils) are entirely surrounded but not engulfed by macrophages as the host cell, but occasionally megakaryocytes and neoplastic could be. Mesothelial cell has been described in a couple of cases of lymphomas affecting serous membranes, but never described in pleuritis. In the present work, the first case of emperipolesis by mesothelial cells in a patient with self-limited pleural effusion was demonstrated by immunohistochemistry and Electron Microscopy studies.

Objectives: Planar cell polarity (PCP) signaling, essential for uniform alignment and directional beating of motile cilia, has been investigated in multiciliated epithelia. As a complex structure connecting the middle ear to the nasopharynx, the eustachian tube (ET) is important in the onset of ear-nose-throat diseases. However, PCP signaling, including the orientation that is important for ciliary motility and clearance function in the ET, has not been studied. We evaluated PCP in the ET epithelium., Study Design: Morphometric examination of the mouse ET., Methods: We performed electron microscopy to assess ciliary polarity in the mouse ET, along with immunohistochemical analysis of PCP protein localization in the ET epithelium., Results: We discovered PCP in the ET epithelium. Motile cilia were aligned in the same direction in individual and neighboring cells; this alignment manifested as ciliary polarity in multiciliated cells. Additionally, PCP proteins were asymmetrically localized between adjacent cells in the plane of the ET., Conclusions: The multiciliated ET epithelium exhibits polarization, suggesting novel structural features that may be critical for ET function., Level of Evidence: NA Laryngoscope, 134:3795-3801, 2024., (© 2024 The American Laryngological, Rhinological and Otological Society, Inc.)

Several morphogenetic sequences occur during esophageal development and birth defects occur due to defects in foregut morphogenesis. This work aimed to record the cellular events in the morphogenesis of rabbits' esophageal epithelium. On the 16th day of gestation, the esophageal epithelium varied from stratified ciliated columnar to stratified squamous type. The surface epithelium presented mucous cells with mucigen granules of various sizes occupying their supranuclear cytoplasm. Cytoplasmic vacuolation was evident in all layers of the esophageal epithelium at this age. On the 18th gestational day, some light cells could be detected in the middle portion of the epithelium, while others occupied the whole epithelial length. On the 21st day, mucous cells are more frequently observed at the apical esophageal part as well as at the surface epithelium. Numerous elongated dark cells could be distinguished embedded between the basal cells. On the 24th gestational day the number of the mucous cells reached its peak. Reaching the 30th gestational day, several lamellar bodies, a keratinized layer and mitotic divisions could be demonstrated, and the number of both mucous and dark cells was greatly decreased. Collectively, detection of surface mucous and dark cells together with the non-cornified surface in some regions of the rabbit esophageal epithelium at the end of gestation ensure a postnatal development to reach the adult epithelium essential to sustain the passage of the harsh raw food. Future immunohistochemical studies are recommended to investigate the components of secretions in mucous cells and functional studies to highlight the dark cells significance. RESEARCH HIGHLIGHTS: Esophageal epithelium of fetal rabbit was analyzed by light and transmission microscopy. Surface epithelium presented mucous cells with mucigen granules of various sizes. They reached their maximum number on 24th day then decreased. On the 16th day, cytoplasmic vacuolation was evident in all epithelial layers. On the 21st day, numerous elongated dark cells could be distinguished embedded between the basal cells. Before birth, several lamellar bodies, a keratinized layer and mitotic divisions could be demonstrated, and the number of both mucous and dark cells was greatly decreased., (© 2023 Wiley Periodicals LLC.)