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ABSTRACT: The epithelial lining of the respiratory tract of urodeles has been shown to harbor an innervated system of neuroepithelial endocrine (NEE) cells. Even between phylogenetically closely related species, large differences have been reported in the appearance and chemical coding of the NEE system. Although urodeles are well suited for the purpose, none of the prior studies have provided an immunocytochemical survey of the NEE system in all parts of the respiratory tract. In the present study, many bioactive substances and a general marker were immunocytochemically demonstrated in serial sections of the entire respiratory tract of the Tokyo salamander, Hynobius nebulosus tokyoensis, a species in which neuroepithelial bodies (NEBs) were previously characterized at the electron microscopic level. In the current study, serotonin-immunoreactive solitary NEE cells were observed in variable numbers in the larynx, in all parts of the trachea, and in areas of the lungs covered with ciliomucous epithelium. Serotonin-containing NEBs, however, were detected in small cranial areas of the lung only. Solitary NEE cells were seen in the trachea and lungs of H. nebulosus tokyoensis by immunocytochemical staining for somatostatin, calcitonin, calcitonin gene-related peptide, and bombesin, but the number, localization, and appearance of the labeled NEE cells differed considerably. Only calcitonin-like immunoreactivity was also noted in some NEB-like cell clusters in the cranial parts of the lungs. Unlike many other vertebrates, neuron specific enolase was found to be a poor marker for the NEE system in the salamander species used in this investigation. It may be concluded that the NEE system of H. nebulosus tokyoensis contains at least five different bioactive substances.(ABSTRACT TRUNCATED AT 250 WORDS)
Histochemistry 01/1995; 102(6):425-31.
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ABSTRACT: The epithelial lining of the respiratory tract of urodeles has been shown to harbor an innervated system of neuroepithelial endocrine (NEE) cells. Even between phylogenetically closely related species, large differences have been reported in the appearance and chemical coding of the NEE system. Although urodeles are well suited for the purpose, none of the prior studies have provided an immunocytochemical survey of the NEE system in all parts of the respiratory tract. In the present study, many bioactive substances and a general marker were immunocytochemically demonstrated in serial sections of the entire respiratory tract of the Tokyo salamander, Hynobius nebulosus tokyoensis, a species in which neuroepithelial bodies (NEBs) were previously characterized at the electron microscopic level. In the current study, serotonin-immunoreactive solitary NEE cells were observed in variable numbers in the larynx, in all parts of the trachea, and in areas of the lungs covered with ciliomucous epithelium. Serotonin-containing NEBs, however, were detected in small cranial areas of the lung only. Solitary NEE cells were seen in the trachea and lungs of H. nebulosus tokyoensis by immunocytochemical staining for somatostatin, calcitonin, calcitonin gene-related peptide, and bombesin, but the number, localization, and appearance of the labeled NEE cells differed considerably. Only calcitonin-like immunoreactivity was also noted in some NEB-like cell clusters in the cranial parts of the lungs. Unlike many other vertebrates, neuron specific enolase was found to be a poor marker for the NEE system in the salamander species used in this investigation. It may be concluded that the NEE system of H. nebulosus tokyoensis contains at least five different bioactive substances. The different markers, however, demonstrate the presence of NEE cells with obvious differences in respect to appearance and topographical distribution. The necessity is emphasized of reliable methods for adequate sampling of all regions of the respiratory tract in comparative histological studies of the NEE system.
Histochemie 11/1994; 102(6):425-431. · 2.59 Impact Factor
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ABSTRACT: Ontogenic changes of the pulmonary epithelium of the rat, ranging from fetal day 15 to 1 hour after birth (21st day), were observed using light and electron microscopy as well as morphometric analysis on the area occupied by terminal segments of epithelial tubes or by alveolar sacs (ATETAS) in the terminal region of the lung. The development of the lung was classified into four stages. In the pseudoglandular period (fetal days 15 and 16), epithelial tubes lined by columnar epithelium were not yet associated with blood capillaries. The percentages occupied by ATETASs in the terminal region of the lung were 15.3% and 15.7%, respectively, on fetal days 15 and 16. In the precanalicular period (fetal days 17 and 18), blood capillaries began to appose to epithelial tubes lined by cuboidal epithelium. Small osmiophilic lamellar bodies (OLBs) emerged in cuboidal epithelial cells (type II cells) on day 18. The percentages occupied by ATETAS were 24.9% and 25.5%, respectively, on days 17 and 18. In canalicular period (fetal days 19 and 20), sac-like end segments showed progressive thinning of the epithelial linings, and the amount of interstital tissues markedly decreased. The epithelial cells differentiated into squamous, or type I cells, and type II cells containing OLBs. Extrusion of OLBs was recognized on day 20. Most of the capillaries were located close to the epithelial linings. The thickness of the blood-air barrier on day 20 was 10 times that of the adult. The percentages occupied by ATETAS were 35.8% and 38.5%, respectively, on days 19 and 20. In the terminal sac period (in neonate), the wall of terminal sacs showed a thin epithelial lining. Blood capillaries protruded close to the air-way surfaces. The thickness of the blood-air barrier was 3.5 times as thick as that of adult. The percentage occupied by ATETAS was 53.1% of the total terminal region of the lung. When the area occupied by ATETAS at a given day was compared to the area of the adult, the percentage on day 20 was approximately 60% of the adult value, whereas the percentage in neonates was 85%. This suggested that a remarkable transformation took place in ATETAS between day 20 and neonate. In addition to the four periods mentioned above, we also discussed the embryonic and alveolar periods in the development of the rat lung.
Anatomical Science International 09/1994; 69(4):392-405.
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ABSTRACT: Despite extensive knowledge of the neuroepithelial endocrine (NEE) system in the lungs of species of various vertebrate classes, data on avians are limited. The present investigation deals with the light- and electron-microscopical immunocytochemistry and morphology of pulmonary NEE cells in the quail, Coturnix coturnix. Light-microscopically, serotonin immunoreactivity was detected in numerous solitary and clustered NEE cells located in the cilio-mucous epithelium of primary and secondary bronchi in adult as well as in newly hatched quails. Only in newly hatched quails could a small number of bombesin- and somatostatin-like immunoreactive NEE cells be demonstrated. Electron-microscopical morphology revealed that NEE cells contained dense-cored vesicles of a wide range of diameters and electron densities. Nearly all of the NEE cells were seen to rest on the basement membrane of the cilio-mucous epithelium, lacking direct contact with the luminal surface. Nerve varicosities or nerve endings, of both afferent and efferent morphological appearance, were found directly apposed to the basal portion of NEE cells, invaginating between NEE cells or between NEE cells and adjacent epithelial cells. Often, synaptic specializations could be recognized between NEE cells and nerve terminals. Electron-microscopical immunocytochemistry confirmed that the intraepithelial serotonin-containing cells correspond to the cells with NEE characteristics. Moreover, two types of NEE cells could be distinguished in newly hatched quail lungs. Both types showed serotonin immunoreactivity selectively distributed over the dense-cored vesicles, but somatostatin- and bombesin-like immunoreactivities were only noted in one of the NEE cell types and were never seen colocalized. Thus, the avian NEE system too, harbors at least three different bioactive substances and has a morphology comparable to that of mammals, reptiles and amphibians.
The Anatomical Record 06/1994; 239(1):65-74.
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ABSTRACT: The alveolar brush cells in the rat lung were observed by transmission electron microscopy. The general structural features of the brush cells in this report were basically in agreement with earlier descriptions. However, this report is the first to detect long, thick microvilli with a unique form protruding into the alveolar lumen in parallel with the basement membrane, not vertically to the basement membrane. Moreover, intranuclear inclusions in the nucleus were observed for the first time in the alveolar brush cells in this study.
Acta Anatomica 02/1991; 141(4):294-301.
