A morphological study of the primary cilia in the rat pancreatic ductal system: ultrastructural features and variability

Primary cilia in the pancreas of the rat were studied by transmission electron microscopy. Their presence is very common, and each ductal cell seems to be provided with a single cilium. The basal body showed anchoring apparatus such as transitional fibers and basal feet. The shaft can show a number of different patterns according to the level of the sections. Proceeding towards the tip, the microtubules decrease in number, although not always in the same way. Near the tip, it is possible to detect patterns, with only 1 microtubule. Three kinds of tips are described. The function of the cilia is discusse

Branching of the foramen rotundum. A rare variation of the sphenoid

The human orbit communicates with the middle cranial fossa through several canals and openings. Some of them (optic canal, superior orbital fissure) are constant, others (meningo-orbital foramen, Warwick's foramen, metoptic canal) are less frequent. Here we report a rare variation of the foramen rotundum which, opening into the orbit with a branching canal, represented a further connecting pathway between the orbit and the middle cranial fossa. Such variation was detected in about 1.06% of individuals and it was almost always located on the right side. Only in one cases it could be found left-sided and in another skull it was spotted bilaterally. The vari- ation consisted of the branching of a 5 mm long canal from the lateral wall of the foramen rotun- dum that opened into the orbit. In general the diameter of the canal was comprised between 0.5 and 0.6 mm but it could be as large as 1 mm or as thin as 0.2 mm. The canal, straight and directed slightly superolaterally, likely transmitted the zygomatic nerve and/or part of the infraorbital nerve. To our knowledge, an independent entrance through a dedicated canal of such nerves has never been reported. The surgeons operating in this region, either neurosurgeons or ophthalmologists, should be aware of the possible variation in the course of these nerves

The revised anatomy of the canals connecting the orbit with the cranial cavity

Orbits are connected with the middle cranial fossa via the optic canal, the superior orbital fissure, the M-type orbitomeningeal foramen, the metoptic canal, an accessory anterior opening of the foramen rotundum, and Warwick’s canal. They are also in communication with the anterior cranial fossa via the ethmoidal canals and the A-type orbitomeningeal foramen. The anatomy of these conduits has been recently enriched with several details that are summarized and reviewed in this article

Dendritic cells in the gut: to sample and to exclude?

Over the past few years one of the most important concepts that emerged in the area of gut immunology derived from the observation by Rescigno et al.1 on the ability of intestinal dendritic cells (DCs) to extend cellular extensions between epithelial cells into the intestinal lumen, to internalize bacteria and shuttle them across the epithelial barrier. This sophisticated mechanism for antigen-sampling complements the well-studied M-cell-mediated transport of particulate antigen and bacteria.2 We have recently reported that DC-mediated sampling is not the only event taking place at the host–pathogen interface in the small intestine during the early stage of bacterial infection. Indeed, a proportion of DCs that rapidly migrate to the lamina propria following challenge with non-invasive Salmonella lacking the Salmonella Pathogenicity Island 1 (SPI1) did not act as an antigen-sampling cell but crossed the epithelium and moved into the gut lumen (Figure 1) before or following internalization of Salmonella.3 The migration of CD11c+CX3CR1+MHCII+CD11b-CD8-DCs was found to be flagellin- and MyD88-dependent, it was restricted to the small intestine and it was not observed in MyD88 mice. Interestingly, intraluminal DCs internalized Salmonella but did not cross the epithelium to return into the tissue. The finding that DCs migrate into the gut lumen following a challenge with a pathogen suggests a few observations. First, it appears that the same antigenic stimulus (e.g., non-invasive Salmonella) can induce DCs to either sample or to migrate into the gut lumen thus showing the complexity of the signaling network operating at the host–pathogen interface; second it tells us that many of the intraepithelial DC extensions previously considered to be "sampling" devices are a feature of DCs undergoing transepithelial migration. At this time the role of the intraluminal "bacteria-capturing" DCs remains to be determined. The migration of phagocytes into the gut lumen was described in the past and it was interpreted as a mechanism of cellular control of the gut pathogens;4, 5 thus, it is possible to hypothesize that DCs are also part of a similar defence mechanism. Sending phagocytes, including DCs, into the lumen of the small intestine would possibly help to limit the number of pathogens that can cross the epithelial barrier and infect the host; a strategy that would complement the immune exclusion mediated by mucous and sIgA antibod

Glial Fibrillary Acidic protein (GFAP)-like immunoreactivity in rat endocrine pancreas

4noreservedThe study of intermediate filament expression in the pancreatic epithelium has been previously focused almost exclusively on cytokeratins. A transient vimentin-immunoreactivity has also been detected within ductal cells in rat foetal pancreas. Here, we report that in rat pancreas an intense GFAP-like immunoreactivity is detectable within a sub-population of endocrine cells located in the periphery of the islet of Langerhans. In addition, staining appeared to be prevalently located in the apical pole of the cells. Two different polyclonal antibodies have been employed in the present study with analogous results. Staining of consecutive sections with anti-GFAP, anti-glucagon and anti-somatostatin antibodies demonstrates that GFAP-like immunoreactivity is present within glucagon-secreting cells. The relevance of this finding is discussed.mixedREGOLI, Marì; ORAZIOLI, Daniela; GERLI, Renato; BERTELLI, EugenioRegoli, Marì; Orazioli, Daniela; Gerli, Renato; Bertelli, Eugeni

Persistence of apoptosis-resistant T cell-activating dendritic cells promotes T helper type-2 response and IgE antibody production

Antigen-specific T cell-mediated apoptosis of dendritic cells (DCs) represents a unique down-regulatory mechanism that prevents the continuous activation of T cells by antigen-loaded DCs; this regulatory mechanism is impaired in allergy and as a consequence a large proportion of DCs tends to escape apoptosis following cognate interaction with CD4+ T cells. However, the biological relevance of greater numbers of apoptosis-resistant DCs to the development of allergic IgE-mediated reactions remained to be determined. Here, we sought to investigate the in vitro and in vivo regulatory features of apoptosis-resistant DCs and to assess their role in host sensitization. Freshly isolated CD11c+/hiB220-DCs from ovalbumin (OVA)-sensitized, OVA-immunized and naïve Balb/c mice were cultured with OVA-specific T cells and levels of T cell-mediated DCs apoptosis assessed by flow cytometry. Surviving apoptosis-resistant DCs were then recovered and subsequently co-cultured with OVA-specific CD62LhiCD44low naïve T cells or passively transferred into naive syngenic recipients. In vitro profile of DC and T cell lymphokine production, chemokine receptors expression and in vivo, post-adoptive DC transfer T helper (TH) and IgE responses were assessed. Apoptosis-resistant DCs showed differential regulatory properties compared to their freshly isolated counterpart independent of the sensitization status of the donor. When co-cultured with naïve OVA-specific T cells, apoptosis-resistant DCs from either sensitized or immunized mice induced T cells that produced increased levels of IL-4 and reduced levels of IFN-γ and showed increased expression of TH-2 related CCR4 and CCR8 chemokine receptors. Finally, adoptive transfer of apoptosis-resistant DCs, induced higher levels of OVA-specific IgE responses in absence of antigen challenge in syngenic recipients compared to freshly isolated DCs from both sensitized and immunized mice. These data would suggest that sensitization-associated increased numbers of apoptosis-resistant T cell-activating DCs contribute to the generation/maintenance of IgE-mediated allergic reaction

Uptake of a Gram-positive bacterium (Streptococcus pneumoniae R36a) by the M cells of rabbit Peyer's patches

4noreservedThe epithelium associated with the lymphoid follicles of Peyer's patches differs from the villi epithelium by the presence of M cells. The main function of these cells is to take up antigens (inert material, viruses and bacteria) from the intestinal lumen. The M cells are able to internalize various different gram-negative bacteria. In order to show the M cells ability to interact and take up a gram-positive bacterium, we exposed rabbit Peyer's patches to Streptococcus pneumoniae R36a. Using the isolated ileal loop technique, Peyer's patches were incubated with a bacterial suspension for varying periods (15, 30, 60, 100 minutes). The bacteria were found outside and inside the M cells. The internalized streptococci could be found in the M cell cytoplasm, in the cytoplasmic "pockets" and inside the intraepithelial lymphoid cells. The finding of internalized bacteria with their damaged walls suggests the possibility that M cells are able to modify internalized antigens in the same way as the antigen presenting cells.mixedREGOLI, Marì; BORGHESI, Chiara; BERTELLI, Eugenio; NICOLETTI, ClaudioRegoli, Mari'; Borghesi, Chiara; Bertelli, Eugenio; Nicoletti, Claudi