Biomedical subjects
Publications and source records attributed to G Corvetti.
The localization and distribution of the Neuropeptide Y (NPY) has been studied with immunofluorescent methods in the human dental pulp. Immunofluorescence for the NPY has been observed in nervous fibers running in medium and big nerves associated in vascular structures, and in single fibers scattered in the pulpar connective or organized in the subdontoblastic plexus.
Substance P-immunoreactive neurons were demonstrated in chick embryonic and adult trigeminal ganglion and jugular-superior ganglionic complex using FITC-immunohistochemical methods. Both small-size and large ganglion cells exhibited SP immunoreactivity, without apparent changes during embryonic and post-hatching development. SP-positive fibers could be detected in a good number in the sympathetic cranial cervical ganglion, either during embryonic development or in adult chick. No immunoreactive perikarya were observed in this ganglion. In the ciliary ganglion, both choroidal and ciliary neurons were SP-negative, whereas SP immunoreactive fibers surrounded the perikarya of both cell populations.
A study was made of the distribution of Substance P-immunoreactive fibers in chick cornea and uvea in whole mount preparation, using the indirect immunofluorescence technique. The development of these fibers during embryogenesis was also investigated. SP-fibers were present in all chick eye structures, in the various prenatal and postnatal stages examined. Their distribution was comparable with that observed by other workers in mammals. Transformation of the iris musculature from smooth to striated, during development, is not accompanied by significant changes in SP-ergic innervation.
Localization and development of chick heart peptidergic innervation (Substance P, VIP and Somatostatin) were investigated by means of immunofluorescence technique. The peptidergic component of the heart innervation was observed, for the first time, in older than 11 day chick embryos, i.e., subsequently to the appearance of the cholinergic component. The peptidergic structures achieve nearly full development in about 16-17 day embryos. Substance P is the most represented of the three peptides. It is localized both in nerve bundle fibers and in isolated fibers within the myocardium, the pericardium, the vessel walls; it is also present in fibers of some heart base ganglia. VIP is mostly contained in some thick single fibers travelling along the vessel walls of the heart base, the myocardium and the pericardium. Some VIP immunoreactive cells were also observed in the base ganglia. Somatostatin is mostly contained in some ganglia cells, whilst thin Somatostatin-immunoreactive fibers form a rich plexus among the atrial and ventricular myofibers, without contacting the vessel walls.
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The origin of the iridial sphincter muscle in chick embryo was investigated by means of immunohistochemistry. Desmin immunoreactive cells are shown in the mesenchymal stroma overlying the anterior epithelial layer of the iris in 4 1/2-day chick embryos. In 9-11-day chick embryos also some cells of the posterior epithelium near the pupillary margin, and of the iridial lamella show a slighter desmin-immunoreactivity. This finding agrees with a double origin of the iridial sphincter muscle: an early mesenchymal one and a later epithelial other.
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Serial sections of stage 18-27 HH (3-5 days of incubation) chick embryo myotomes were investigated by electron microscope. Two morphologically different types of contractile elements (myoblasts and myotubes) with an exact and constant localization were identified. Myotome sections of other chick embryos in the same stages were examined with the immunofluorescence technique, after treatment with antisera directed against fast and slow adult myosins. As from stage 24 HH, some contractile elements react positively with anti-fast adult myosin antiserum, others with anti-slow antiserum. A very precise correspondence was constantly found between the ultrastructural and immunohistochemical findings. An identical pattern was observed in the buds of the fast-twitching pectoralis major and posterior latissimus dorsi and slow-twitching anterior latissimus dorsi muscles.
The distribution of fibronectin (FN) in the dental pulp and gingiva of the human adult was investigated by indirect immunofluorescence and indirect immunoperoxidase techniques. FN could not be demonstrated in the connective tissue of the dental pulp even in the blood vessels. On the contrary, a positive stain was obtained in the ground substance at the base of the odontoblast cell bodies and in various structures of a denticle which was accidentally found in the pulp of one of the examined teeth. The lack of FN in the dental pulp could mean that this tissue, sometimes considered to be of an immature and undifferentiated type, is instead a mature one. The subepithelial connective tissue and the epithelium of the gingiva were examined. The distribution of FN in the connective tissue of the gingiva was found to be similar to that described in other types of connective tissue; high concentrations were found both in the epithelial cells and around them. This finding is described here for the first time and remains to be verified in other types of stratified epithelia.
The authors focused their attention on the cytology of the degenerating notochord at the level of the vertebral anlagen and compared it with data of the literature on the histopathology of the spinal chordomas. The purpose of the research was to investigate the notochordal histological features justifying the fact that the remnants of a structure destined to atrophy during prenatal life, maintain a proliferative potential in postnatal life. Therefore, from the earliest stages (24th incubation hour) to the terms of development, the notochord was studied by electron microscope in chick embryo. The data obtained show that, in most notochordal cells, signs of metabolic damage and progressive degeneration coexist with signs of secretory and mitotic activity, from which the proliferative potential of these cells seems to derive. Vacuolar degeneration is also likely due to the progressive metabolic segregation of the notochord, owing to the absence of blood-vessels and the appearance of perichordal sheath.
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