Use of biocytin as neuroanatomic tracer in harvested human pancreas: a confocal laser scanning microscopy analysis

INTRODUCTION: To identify central neuroanatomic structure, biocytin labeling has recently been used. To date, there are no bibliographic references about the use of this molecule in investigations of the peripheral nervous system. In the present study, fresh, harvested human pancreas was used to evidence pancreatic innervations by biocytin. AIM: To investigate for the first time pancreatic innervation in harvested pancreas from human multiorgan cadaveric donors. METHODOLOGY: Biocytin labeling was used as a neuroanatomic tracing method, and confocal laser scanning microscopy was used for analysis for description by means of high-resolution images. RESULTS: The application of biocytin-avidin staining in harvested human pancreas revealed numerous bundles of nervous fibers, intrapancreatic ganglia, few small solitary neurons, and a large number of positive supporting cells (glial-like cells). Biocytin appeared to pass through gap junctions between glial elements and neurons and among the neurons. In human pancreas, biocytin is rapidly transported in both anterograde and retrograde directions, with consequent visualization of fine details of pancreatic innervation morphology. Indeed, evidence of anterograde and retrograde transportation of biocytin has been demonstrated in the extensive labeling of pancreatic preganglionic and postganglionic fibers as well as a great number of chemical buds that wind through exocrine tissue or undetermined target cells. CONCLUSION: To our knowledge, this is the first report of the successful use of biocytin in neuronal retrograde and anterograde labeling in the human peripheral nervous system.