Innervation of rabbit fetal lungs

Hung, Kuen‐Shan

doi:10.1002/aja.1001590107

Cited by 40 publications

(20 citation statements)

References 27 publications

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“…They are present and to some extent are functional in intrapulmonary airways down to the bronchiolo-alveolar junctions before birth. These findings complement those of other, variably systematic studies of rabbit (Sonstegard et al, 1979;Hung, 1980;Lauweryns and de Bock, 1981) and mouse (Hung, 1982), and recent studies of human lung (Cutz et al, 1981Cutz, 1982) carried out by scanning and transmission electron microscopy, histochemistry, and immunocytochemistry.…”

supporting

confidence: 88%

Development of neuroepithelial bodies in intact and cultured lungs of fetal rats

1985

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Intact, 14- to 21-day fetal rat lung pairs, neonatal lungs, and cultured 15- and 16-day lung explants were examined in 2-micron-thick glycol methacrylate sections stained by PAS-lead hematoxylin. Selected stages were also studied in histochemical preparations for aliesterase and formaldehyde-induced monoamine fluorescence, as well as by scanning and transmission electron microscopy. Neuroepithelial bodies (NEBs) first appear in pseudoglandular lungs at 15 days in vivo as pyramidal groups of basal, diffusely lead-hematoxylin-positive cells in glycogen-depleted epithelium of main and lobar bronchi. By day 16, primitive NEBs occur within three to four generations of the terminal buds, and older, proximal bodies are larger and more distinctive than at 15 days. Aliesterase activity is first detected in basally located, developing NEBs on day 16. During the canalicular and alveolar sac periods, NEBs appear and mature on a proximal-to-distal gradient along the airway, as they do in developing rabbit and human lungs. As earlier-formed airways elongate, additional NEBs appear and supplement the population already present. By days 20-21, NEBs occur at all airway levels down to the bronchiolo-alveolar junctions, and many of the cells have discrete PAS- and lead-hematoxylin-positive, infranuclear granules. Near term some NEBs exhibit serotonin fluorescence after incubation in 5-hydroxytryptophan and have abundant, ca. 100-nm, electron-dense granules. These are concentrated toward the cell base like the stained granules visualized by light microscopy. Similar results were obtained from lungs placed in organ culture. From 2 days in culture to a time equivalent to term, NEB formation parallels that in vivo, indicating that developmental requirements are met in in vitro. Taken altogether, morphologic and cytochemical evidence suggests that NEBs of rats are functional in late fetal life and that their development is relatively independent of extrapulmonary influences and of the intraepithelial ingrowth of sensory nerve endings.

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confidence: 88%

Development of neuroepithelial bodies in intact and cultured lungs of fetal rats

1985

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“…,Sorokin and Hoyt {30],Sonstegard et al [lb), and Hung[50]. These investigations, and the cytochemical and ultrastuctural study presented here, indicate that the structure and cy-Pooled, separated cell fractions incubated with and without the arnine precursor,5-hydroxytryptophan (5-HTP).…”

mentioning

confidence: 48%

Morphological and Cytochemical Characterization of Neuroepithelial Bodies in Fetal Rabbit Lung I. Studies of Isolated Neuroepithelial Bodies

Sonstegard

Mailman

Cheek

et al. 1982

Experimental Lung Research

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Neuroepithelial bodies (NEB) in 29-day fetal rabbit lung were examined by light microscopy and cytochemistry to demonstrate their structural and biochemical properties in situ. Longitudinal sections of NEB at airway bifurcations demonstrated their chemoreceptor-like appearance. Furthermore, the cytochemical presence of serotonin, acetylcholinesterase, formaldehyde-induced fluorescence, and silver-staining properties demonstrated the neural-like biochemical properties of NEB cells. Forty-one NEB and eight single neuroendocrine cells from whole fetal lungs were examined ultrastructurally. Juxtaluminal junctional complexes composed of tight and intermediate junctions, desmosomes, and cytoplasmic filaments were demonstrated in the corpuscular-shaped NEB. Basal bodies were apparent in NEB cell cytoplasm; cilia extended from NEB cells. Dense-core vesicles (DCV) were of at least three types: type 1, type 2, and enterochromaffin type. The majority of epithelial cells adjacent to NEB in near-term airway epithelium were undifferentiated, with large amounts of glycogen. However, ciliated cells were adjacent to some small NEB and single neuroendocrine cells; mucus or Clara-type cells were not observed. NEB isolated by collagenase treatment revealed an intact organoid structure, DCV, and desmosomes and retained their argyrophilia and formaldehyde-induced fluorescence. NEB were recovered in cell fractions separated by unit gravity that had cells in clumps of four or more. One to five NEB stained with silver in cytocentrifuge preparations of control, mixed cells, whereas up to 20 intact NEB were demonstrated in the clump-containing, separated fractions. We propose that isolated NEB retain certain biochemical and metabolic properties similar to those of their counterparts in situ. Serotonin and 5-hydroxyindole acetic acid were found by high-performance liquid chromatography analysis in the fractions containing NEB, and amine precursor uptake and decarboxylation (APUD) activity were demonstrated. Moreover, muscarinic cholinergic receptors were detected, consistent with the occurrence of acetylcholinesterase in NEB. The elution profile of bombesin radioimmunoactivity substantiated that isolated fetal rabbit NEB contained this neuropeptide and that NEB were enriched by unit gravity sedimentation. These studies suggest that NEB are structurally and functionally developed before other cell types in immature airway epithelium and can be isolated as intact organoids, which retain some of their structural and metabolic integrity.

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“…Positive staining of NEB cells (but not single NE cells) for acetylcholinesterase (AChE) in newborn rabbits was first reported by Lauweryns et al 112). In a recent study of the development of innervation in rabbit fetal lungs, Hung found AChE reactivity in NEB before the appearance of amine fluorescence [44]. AChE staining in NEB appears specific, because the reaction was not abolished after incubation with inhibitor of nonspecific esterase (iso-OMPA) and was blocked by addition of AChE inhibitor, eserine [ 12,441. In the rabbit fetus, the AChE-positive NEB generally correspond to those shown by AG stains or amine fluorescence (Fig.…”

Section: Acetylcholinesterasementioning

confidence: 98%

Neuroendocrine Cells of the Lung an Overview of Morphologic Characteristics and Development

Cutz

1982

Experimental Lung Research

134

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The detailed morphology of pulmonary neuroendocrine (NE) cells has been defined only during the last decade. The purpose of this paper is to review the main morphologic features of the NE cells, to review the methods and techniques used for their identification, and to discuss the development and functional significance of these cells. The main emphasis is on NE cells in human lung, but where appropriate, studies in animal lungs are also included. NE cells are present in the airway epithelium of human and various animal species and occur singly as well as in clusters called neuroepithelial bodies (NEB). The general cytochemical features (common to both single NE cells and NEB) include cytoplasmic argyrophilia, fluorogenic amine content, positive staining with lead-hematoxylin, and masked metachromasia. These staining properties are similar to those found in APUD cells scattered in various tissues. More specific cell markers are immunoreactivity to peptide hormones (bombesin, calcitonin, leu-enkephalin) identified so far in NE cells of human lung, and immunoreactivity to serotonin found in both human and animal lungs. At the ultrastructural level, NE cells are characterized by the presence of cytoplasmic dense core granules (90-150 nm in diameter), which are considered the storage site of amine and peptide hormones. The distinctive feature of NEB, not found with single NE cells, is the presence of nonmyelinated nerve endings in contact with granulated cells, and positive staining for acetylcholinesterase. The single NE cells are scattered throughout the tracheobronchial epithelium, whereas NEB are found only within the intrapulmonary airways. In postnatal lungs, both the single NE cells and NEB appear concentrated in small peripheral airways. In developing human lung, the first NE cells appear at 8 weeks' gestation, when all other epithelial cells are still undifferentiated. The development and cytodifferentiation of NE cells progresses in a centrifugal direction. By the end of the glandular period, single and groups of NE cells are found along the entire length of primitive bronchial epithelium. Based on differences in the size and morphology of cytoplasmic granules, three distinct types of NE cells can be recognized. During terminal stages of development, NE cells appear in small peripheral airways and primitive saccules. The functional considerations include the possible role of NE cells as endocrine, paracrine, or receptosecretory cells involved in neurohormonal regulation of pulmonary vascular or bronchial responses, and possible function of NEB as intrapulmonary hypoxia-sensitive chemoreceptors.

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Innervation of rabbit fetal lungs

Cited by 40 publications

References 27 publications

Development of neuroepithelial bodies in intact and cultured lungs of fetal rats

Development of neuroepithelial bodies in intact and cultured lungs of fetal rats

Morphological and Cytochemical Characterization of Neuroepithelial Bodies in Fetal Rabbit Lung I. Studies of Isolated Neuroepithelial Bodies

Neuroendocrine Cells of the Lung an Overview of Morphologic Characteristics and Development

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