Morphological pattern of intrinsic nerve plexus distributed on the rabbit heart and interatrial septum.

Although the rabbit is routinely used as the animal model of choice to investigate cardiac electrophysiology, the neuroanatomy of the rabbit heart is not well documented. The aim of this study was to examine the topography of the intrinsic nerve plexus located on the rabbit heart surface and interatrial septum stained histochemically for acetylcholinesterase using pressure-distended whole hearts and whole-mount preparations from 33 Californian rabbits. Mediastinal cardiac nerves entered the venous part of the heart along the root of the right cranial vein (superior caval vein) and at the bifurcation of the pulmonary trunk. The accessing nerves of the venous part of the heart passed into the nerve plexus of heart hilum at the heart base. Nerves approaching the heart extended epicardially and innervated the atria, interatrial septum and ventricles by five nerve subplexuses, i.e. left and middle dorsal, dorsal right atrial, ventral right and left atrial subplexuses. Numerous nerves accessed the arterial part of the arterial part of the heart hilum between the aorta and pulmonary trunk, and distributed onto ventricles by the left and right coronary subplexuses. Clusters of intrinsic cardiac neurons were concentrated at the heart base at the roots of pulmonary veins with some positioned on the infundibulum. The mean number of intrinsic neurons in the rabbit heart is not significantly affected by aging: 2200 ± 262 (range 1517-2788; aged) vs. 2118 ± 108 (range 1513-2822; juvenile). In conclusion, despite anatomic differences in the distribution of intrinsic cardiac neurons and the presence of well-developed nerve plexus within the heart hilum, the topography of all seven subplexuses of the intrinsic nerve plexus in rabbit heart corresponds rather well to other mammalian species, including humans.

Application of acetylcholinesterase histochemistry for the diagnosis of Hirschsprung's disease in neonates and infants: a twenty-year experience.

BACKGROUND: The acetylcholinesterase (AChE) histochemical staining of intestinal mucosal-submucosal biopsy specimens is believed to be the most reliable diagnostic method for Hirschsprung's disease (HD). The aim of our study was to evaluate advantages and disadvantages of this method for HD diagnosis in infants and neonates. MATERIAL AND METHODS: The results of AChE histochemistry of rectal biopsy specimens, obtained from 11 neonates and 29 infants treated in the Clinic of Pediatric Surgery, Hospital of the Lithuanian University of Health Sciences, from 1991 to 2010 were analyzed. AChE activity of neural structures was evaluated using Karnovsky-Roots method modified by El-Badawi and Schenk. RESULTS: Two neonates were diagnosed with HD. The diagnosis was not confirmed in 9 cases, but clinical symptoms progressed in 3 cases, and HD was diagnosed after the repeated biopsy performed in infancy. The results of primary biopsy were rated as false negative. Test sensitivity and specificity in neonates were 40.0% and 100%, respectively. A total of 21 infants were diagnosed with HD. All of them underwent surgery. The diagnosis of HD was confirmed in 20 cases; in one case, intestinal neuronal dysplasia type B was diagnosed. The diagnosis was not confirmed in 8 cases. In infants, the test had a sensitivity of 100% and a specificity of 88.8%. CONCLUSIONS: The analysis of AChE activity in rectal biopsy specimens is a reliable method for diagnosing HD in infancy. This test is less valuable in neonates. If test results are negative, infants should be observed, and if symptoms persist, the biopsy should be repeated at the age of 3 months. Rectal biopsy specimens in neonates should include mucosa and submucosa.