Polarized Ends of Human Macula Densa Cells: Ultrastructural Investigation and Morphofunctional Correlations

ABSTRACT The morphology of the kidney macula densa (MD) has extensively been investigated in animals, whereas human studies are scanty. We studied the fine structure of human MD cells focusing on their apical and basal ends and correlating structure and function. The MD region was examined by transmission electron microscopy in six renal biopsies from patients with kidney disease. Ultrastructural analysis of MD cells was performed on serial sections. MD cells show two polarized ends. The apical portion is characterized by a single, immotile cilium associated with microvilli; apically, cells are joined by adhering junctions. In the basal portion, the cytoplasm contains small, dense granules and numerous, irregular cytoplasmic projections extending to the adjacent extraglomerular esangium. The projections often contain small, dense granules. A reticulated basement membrane around MD cells separates them from the extraglomerular mesangium. Although the fact that tissue specimens came from patients with kidney disease mandates extreme caution, ultrastructural examination confirmed that MD cells have sensory features due to the presence of the primary cilium, that they are connected by apical adhering junctions forming a barrier that separates the tubular flow from the interstitium, and that they present numerous basal interdigitations surrounded by a reticulated basement membrane. Conceivably, the latter two features are related to the functional activity of the MD. The small, dense granules in the basal cytoplasm and in cytoplasmic projections are likely related to the paracrine function of MD cells

Le colture cellulari da brushing nasale: un nuovo metodo per semplificare l’iter diagnostico nei casi dubbi di discinesia ciliare primaria

Per evitare di sottoporre i bambini affetti da una discinesia ciliare di difficile inquadramento ad un lungo follow-up e a più prelievi di mucosa nasale, a distanza l’uno dall’altro, necessari per la valutazione sia della funzione delle ciglia respiratorie che della loro ultrastruttura, abbiamo sviluppato un metodo di coltura delle cellule ciliate nasali più semplice,ma idoneo allo studio della ciliogenesi. Ciò ha consentito di verificare se le ciglia respiratorie di tali pazienti, ottenute mediante brushing (anziché, come in passato, con biopsia), potevano recuperare la normale ultrastruttura e movimento in un ambiente privo di noxae patogene, dando un contributo decisivo alla diagnosi dei casi incerti

Rapid diagnosis of primary ciliary dyskinesia: cell culture and soft computing analysis

Diagnosis of primary ciliary dyskinesia (PCD) sometimes requires repeated nasal brushing to exclude secondary ciliary alterations. Our aim was to evaluate whether the use of a new method of nasal epithelial cell culture can speed PCD diagnosis in doubtful cases and to identify which are the most informative parameters by means of a multilayer artificial neural network (ANN). A cross-sectional study was performed in patients with suspected PCD. All patients underwent nasal brushing for ciliary motion analysis, ultrastructural assessment and evaluation of ciliary function after ciliogenesis in culture by ANN. 151 subjects were studied. A diagnostic suspension cell culture was obtained in 117 nasal brushings. A diagnosis of PCD was made in 36 subjects (29 of whom were children). In nine out of the 36 patients the diagnosis was made only after a second brushing, because of equivocal results of both tests at first examination. In each of these subjects diagnosis of PCD was confirmed by cell culture results. Cell culture in suspension evaluated by means of ANN allows the separation of PCD from secondary ciliary dyskinesia patients after only 5 days of culture and allows diagnosis to be reached in doubtful cases, thus avoiding the necessity of a second sample