Ultrastructure and immunocytochemistry of the neuroepithelial bodies in the lung of the tiger salamander,Ambystoma tigrinum (Urodela,amphibia)

Light and electron microscopy of the lungs of Ambystoma tigrinum (Urodela) revealed a relatively complex pattern of the neuroendocrine (NE) cells. In the apical parts of smaller septa single NE cells not associated with nerve fibres were covered and surrounded by pneumocytes. The larger septa possessed small areas of ciliated epithelium, in which the NE cells were grouped in a form of neuroepithelial bodies (NEB) consisting of 3–5 cells and covered by goblet cells. NE cells possessed a large nucleus with patches of condensed chromatin, clear cytoplasm, and membrane-bound vesicles of variable morphology and size, of these dense core vesicles (DCV) ranged from 70–140 nm, while rarely the larger ones exhibited a diameter of 300–600 nm. In some NEB a second type of NE cells was observed for the first time in an amphibian species: these cells communicated with the air space and exhibited on their surface microvilli and a single modified cilium with a 8+1 microtubule arrangement. Their cytoplasm contained two types of DCV: dense core granules with a diameter of 140–260 nm and vesicles 320–700 nm in diameter with a moderately electron dense interior. The NEB were associated with intracorpuscular, sensory nerve terminals morphologically afferent and efferent. By immunocytochemistry, the NE cells revealed the presence of serotonin, met-en-kephalin, and leu-enkephalin. A paracrine and chemoreceptor role is proposed for NEB of Ambystoma tigrinum.© Willey-Liss, Inc.     

Congenital muscular dystrophy associated with lethal arthrogryposis multiplex congenita

Summary Two unrelated patients with severe arthrogryposis multiplex congenita (AMC) who died perinatally, are presented. In both, postmortem examination revealed an intact nervous system and striking dystrophic muscle changes, consistent with congenital muscular dystrophy (CMD). Few similar cases have been reported before, but since the condition is not well known, it seems probable that in the past many have been labeled as mere multiple malformations. The possibility of an underlying muscular disorder, either primary myopathic or neurogenic should be considered in any patient with early lethal AMC. Our findings confirm that the fetal akinesia-arthrogryposis sequence is a nonspecific clinical syndrome resulting from various causes of muscular inactivity in utero. The main objective of this report is to provide reasonable guidelines on how to approach the problem of classification. We favor a pathogenetic approach, depending upon careful sampling of the central nervous system and skeletal muscles at autopsy.     

Postnatal maturation of neuroepithelial bodies and carotid body innervation: a quantitative investigation in the rabbit

The intrapulmonary airways contain oxygen-sensitive chemoreceptors which may be analogous to the arterial chemoreceptors: the neuroepithelial bodies (NEB). While the NEB are prominent in the neonatal lung, physiological studies indicate that the carotid bodies are still relatively inactive at birth. This points to an unequal degree of development of both during the early neonatal period. As a reflexogenic chemoreceptor function depends on a well-developed innervation, we undertook a comparative investigation of the development of the NEB and the carotid body glomus cell innervation. Two morphological aspects of the innervation of NEB and carotid body glomus cells were quantified in rabbits of different age groups. The total sectional area of intracorpuscular and intraglomerular nerve endings per NEB or glomus cell group, respectively, was measured and the area percentage of mitochondria and synaptic vesicles was determined. In the NEB, no significant difference in total sectional area of the nerve endings between the age groups was observed, while in the carotid body there was a significant increase in the adult age group. In addition, the area percentage of mitochondria and synaptic vesicles of the nerve endings did not change significantly with age in the NEB, while in the carotid body these increased and decreased, respectively, with age. These observations point to a shift from morphologically efferent nerve endings, rich in synaptic vesicles, to morphologically afferent nerve endings, rich in mitochondria. Our interpretation of these findings is that, at birth, the NEB innervation is more mature than the carotid body glomus cell innervation and that the latter matures at a later time than the former. These findings support the theory that the NEB may act as complementary chemoreceptors to the carotid body during the early postnatal period.     

The pulmonary neuroendocrine system: the past decade

The pulmonary neuroendocrine system consists of specialized airway endocrine epithelial cells, associated with nerve fibres. The epithelial cells, the pulmonary neuroendocrine cells (PNEC), can be solitary or clustered to form neuroepithelial bodies (NEB). During the last thirty years, the pulmonary neuroendocrine system has been intensively investigated and much knowledge of its function has been obtained. This text reviews work which dates from the last ten years. In this period, the picture of the pulmonary neuroendocrine system we previously had, has not fundamentally changed. The pulmonary neuroendocrine system is still regarded as an oxygen sensitive chemoreceptor with local and reflex-mediated regulatory functions, and as a regulator of airway growth and development. Continuing research has much more refined this picture. This text reviews several aspects of the pulmonary neuroendocrine system: phylogeny, the amine and peptide content of its epithelial cells, ontogeny and influence on lung development, the influence of hypoxia and nonhypoxic stimuli, immunomodulatory function, innervation and pathology. Among the discoveries of the past decade, three stand out prominently because of their great significance: additional proof that the neural component of the pulmonary neuroendocrine system is sensory, sound experimental evidence that PNEC stimulate airway epithelial cell differentiation and the discovery of a specific membrane oxygen receptor in the PNEC.     

The senile lung. Comparison with normal and emphysematous lungs. 1. Structural aspects.

As part of a study of the structural-functional correlations of excised human lungs obtained at autopsy, the parenchyma and peripheral airways were examined by means of morphometric techniques. Among the 30 lungs characterized by the absence of fibrosis, ten differed from the normal and emphysematous lungs by a homogeneous dilatation of the airspaces, in excess of the dimensions predicted on the basis of age. Study of the standard deviations of the mean linear intercepts showed that the airspace dilatation was more regular than in emphysematous lungs; in addition, there was no clear-cut destruction, as estimated from the number of alveolar attachments. These lungs were characterized in addition by an increased thickening of alveolar septa, without inflammation or fibrosis, normal size of the diameter, and reduced density of the membranous bronchioles. Since these lungs were from people older than 60 years, it is assumed that they represent cases of exaggerated airspace enlargement of the aging lung, differing from emphysema by the absence of destruction of alveolar walls. The term "senile lung" is proposed or this condition.     

Interrupted right aortic arch in DiGeorge syndrome.

The clinical and necropsy findings in four cases of interrupted right aortic arch and right descending aorta associated with DiGeorge syndrome (congenital absence or hypoplasia of the thymus and parathyroids) are described. All patients had a mirror image of type B interruption, namely a right aortic arch with reversed branching pattern and an interruption between the right common carotid and right subclavian artery. In two patients there was a doubly committed subarterial ventricular septal defect and in the two other patients there was a perimembranous septal defect. Three patients had a bicuspid aortic valve. In a consecutive series of 185 necropsies in infants and children with congenital heart disease there were no cases of interrupted right aortic arch that were not associated with DiGeorge syndrome. These observations and previous reports indicate that the concurrence of these two rare conditions is more than fortuitous. In patients with an interrupted aortic arch the clinician should be aware of the common association with DiGeorge syndrome. If the interruption is associated with a right-sided descending aorta it is highly probable that the patient has DiGeorge syndrome.     

Transient synovitis of the hip in children: role of US

Transient synovitis of the hip remains a common diagnostic problem for the clinician. The physical signs are not pathognomonic of the condition, and the classic technical examinations are of little help. Therefore, the authors retrospectively studied the value of hip arthrosonography in 46 children with clinical symptoms suggesting pathologic hip conditions. In 20 of the 21 patients with a final diagnosis of transient synovitis, articular effusion was detected on ultrasound (US). Conventional radiography showed an increased medial joint space in only eight of these patients. Increased echogenicity of the articular fluid was found in both transient synovitis and septic arthritis. The high sensitivity of US in detecting intraarticular fluid was demonstrated by cadaver studies.     

Uneven Lipomatosis: A pitfall in pancreatic Sonography

A marked difference in echogenicity between the anterior and posterior parts of the pancreatic head was demonstrated by pancreatic ultrasound in 4 patients. This finding could not be related to local pancreatic or peripancreatic pathology. In all patients the dorsal portion of the head, including the uncinate process, appeared less echogenic than the ventral part of the head, body, and tail. The level of demarcation was identical in all 4 cases, coinciding with the expected fusion line of the embryological dorsal and ventral pancreatic origin. Pathology available in 1 patient showed an uneven lipomatosis as an explanation for this hitherto unreported observation.