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  • Articles: DFG German National Licenses  (7)
  • Cell & Developmental Biology  (7)
  • 1
    Electronic Resource
    Electronic Resource
    A novel mechanism of capillary growth in the rat pulmonary microcirculation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 228 (1990), S. 35-45 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Postnatally, the rat lung parenchyma undergoes impressive growth. Within four months of birth, lung volume and alveolar and capillary surface areas increase over 20-fold and capillary volume 35-fold. Investigation of methacrylate casts of the pulmonary microvasculature revealed that, with age, lung capillaries were not only growing in surface and volume but also increasing their network density. We proposed that the capillary bed grows by formation of slender intravascular tissue pillars and termed this type of growth intussusceptive microvascular growth (Caduff et al., Anat. Rec., 216:154-164, 1986). The aim of this investigation was to detect the presence and to analyze the ultrastructure of slender tissue posts (diameter 1-2.5 μm) extending across the capillary lumina in serial electron microscopic sections of rat lung parenchyma (age 44 days). Computer-assisted three-dimensional reconstruction of the capillary lumen confirmed that tissue posts were matching the holes previously observed in casts. Post ultrastructure varied with size from a simple area of interendothelial contact to tissue pillars with a core of interstitial tissue. Based on the changing morphology of the pillars, a hypothesis for their development can be proposed: phase I, creation of a zone of contact between opposite capillary walls (formation of an interendothelial bridge); phase II, reorganization of the intercellular junctions of the endothelium, with central perforation of the capillary layer; phase III, formation of an interstitial post core, with successive invasion by cytoplasmic extensions of myofibro-blasts, pericytes, and finally interstitial fibers; and phase IV, growth of the slender pillar to a normal full size capillary mesh. These findings support the new concept of intussusceptive growth of the lung capillary system.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092280107
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  • 2
    Electronic Resource
    Electronic Resource
    The postnatal growth of the rat lung III. MorphologyThis study was supported by grants 3.5.68 and 3.682.71 from the Swiss National Science Foundation. (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 77-98 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to investigate the postnatal growth of the gas exchange apparatus, the lungs of rats aged 1, 4, 7, 10, 13, and 21 days were fixed by intra-tracheal instillation of glutaraldehyde. The analysis and interpretation of the morphological changes observed by light and electron microscopy were based on the results of previous morphometric and autoradiographic studies performed on the same material.The newborn rat has no alveoli, but breathes with smooth walled air channels and saccules, which correspond to the prospective alveolar ducts and alveolar sacs, respectively. The bulk of alveoli are formed between days 4 and 13 by a rapid outgrowth of secondary septa from the primary septa present at birth. The arrangement of elastic fibers during this period suggests that these may play a role in septal outgrowth. Based on ultrastructural observations a model is described for the capillarisation of the secondary septa. Some evidence is given that alveoli may also be formed by outpouchings in the walls of terminal bronchioles.Primary and secondary septa have initially an immature appearance. They both show an apparently double capillary network, whereas the mature interalveolar septum is just wide enough to accommodate a single capillary. Possible mechanisms for this structural transformation which occurs within three weeks after birth are discussed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091800109
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  • 3
    Electronic Resource
    Electronic Resource
    The postnatal growth of the rat lung II. AutoradiographyThis study was supported by grants from the Council for Tobacco Research U.S.A. and from the Swiss National Science Foundation 3.5.68 and 3.682.71. (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 63-76 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Combined morphometric and autoradiographic methods were used to analyze the postnatal growth of rat lung from 1-21 days after birth. Each cell population had distinct growth patterns with an increase in the number of fibroblasts and capillary endothelial cells largely determining the increase in interstitial volume and capillary surface, respectively. The height of proliferation activity in mesodermally-derived cells was concurrent with the outgrowth of secondary alveolar septa (between days 4 and 13). Analysis of the location of labeled cells on day 7 showed that the higher labeling index on septal crests could be ascribed to the proliferative activity of fibroblasts and endothelial cells.Within the alveolar epithelium only the type II alveolar cells had a detectable labeling index. Over the first week, the number of type I epithelial cells steadily increased while the number of type II cells remained constant. Subsequently the number of type II cells increased rapidly, reached a peak on day 13 and then decreased, whereas type I cells continued to increase in number. These facts led us to consider that type II epithelial cells may represent the stem cell population of alveolar epithelium. The height of proliferative activity of type II cells on day 7 coincided with the outgrowth of septal crests and was followed by the steepest increase in number of type I and II cells.Between the 10th and 21st day labeling indices rapidly declined, cell production became undetectable after day 13. Increase in alveolar and capillary surface area however continued, resulting in a thinning of the interstitial layer and of the epithelial and endothelial sheets.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091800108
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  • 4
    Electronic Resource
    Electronic Resource
    Morphometric analysis of the remodeling of the rat pulmonary epithelium during early postnatal development (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 207 (1983), S. 317-324 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In the rat lung the alveoli are formed in the early postnatal period. Within 3 weeks the alveolar surface area increases more than five-fold and the saccular lung reaches its mature structure. In order to analyse the changes in the compartments of the parenchymal tissue, the lungs of three animals per group aged 4, 13, and 21 days, respectively, were investigated by means of electron microscopic morphometry.Whereas the capillarisation of the interalveolar septa almost doubled in the period investigated, the endothelium and alveolar epithelium increased their share of the septal tissue at the expense of the interstitial compartment. The cellularity of the interstitium decreased markedly with age, the ratio of cells to interstitial spaces falling from 5.1 to 1.7. Within the epithelium, the type II cell population increased its mass almost six times, representing 58% of the alveolar epithelial volume at 3 weeks. Accordingly, the portion of alveolar surface area covered by type II cells was highest on day 21, with 9% versus 5.6% on day 4, and around 3% in a normal adult lung.The observed quantitative structural changes are discussed in the light of the functional demands of the organ: the need for an expanding alveolar surface area to be covered by a thin epithelial lining layer, the maintenance of a thin air-blood barrier, and a quantitatively adapted secretion of alveolar surfactant.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092070210
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  • 5
    Electronic Resource
    Electronic Resource
    Morphometric analysis of fetal rat lung development (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 237 (1993), S. 38-48 
    Details
    ISSN: 0003-276X
    Keywords: Lung development ; Fetal rats ; Lung compartments ; Lung parenchyma ; Airways ; Pulmonary vasculature ; Cellular differentiation ; Morphometry ; Reference space ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Applying the zone concept described previously, we quantitatively analyzed fetal rat lung development. The zone concept allowed us to coherently define reference spaces in the developing lung, a prerequisite for morphometric analysis.The peripheral zone I corresponds to a zone of growth of yet undifferentiated tissues; zone II arises from zone I and represents a region of structural and cellular differentiation; zones III and IV comprise the conducting airways and vessels.Lungs of fetal rats aged 17-23 days and 20 hours postnatal were fixed with OsO4 and glutaraldehyde and processed for light and electron microscopic morphometry implemented by point and intersection counting.Fetal lung volume grew in proportion to body weight. Zone II being the largest compartment, its volume changes largely determined lung growth rates. Zone II increased in mass owing to differentiation processes at the interface to zone I where the proximal portions of zone I were continuously shifted into zone II by differentiation. New tissue was generated within zone I. Due to these combined processes zone I changed little in volume until it disappeared at the end of the canalicular stage. The presence in the pseudoglandular stage of half of the parenchymal epithelial mass available around birth indicated that parenchymal development started earlier than assumed so far.While the endothelial surface increased most at birth, the epithelial surface grew by more than 600% at day 21, reflecting the onset of canalisation.The study confirmed the usefulness of the zone concept for morphometry and provided some new insights into lung development. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092370105
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  • 6
    Electronic Resource
    Electronic Resource
    The postnatal growth of the rat lung.This study was supported by grants 3.5.68 and 3.682.71 from the Swiss National Science Foundation. I. Morphometry (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 178 (1974), S. 711-730 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The postnatal growth of the lung was quantitatively investigated in rats aged 1, 4, 7, 10, 13, 21, 44 and 131 days by light and electron microscopic morphometry.Lung volume (VL) increased first directly with body weight (W). After day 10 VL followed the function W0.70. Based on the quantitative findings the postnatal lung growth could be divided into three phases.1Lung expansion (up to day 4): Lung volume increase resulted almost exclusively from an 87% enlargement of the existing air spaces.2Tissue proliferation (day 4 to 13): All tissue compartments showed a pronounced mass increase, followed by a high gain in capillary volume. Alveolar and capillary surface areas (Sa, Sc) developed rapidly due to subdivision of the primitive air sacs.3Equilibrated growth (third week to adult age): An initial period of redistribution of tissue mass with septal lengthening and further rapid increase in Sa and Sc was followed by proportionate alveolar growth. In the adult further lengthening of the interalveolar septa or continued alveolar formation could not be excluded.During the period of fundamental internal remodelling of the lung, its function, as determined by the morphometric pulmonary diffusing capacity, was not impaired.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091780405
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  • 7
    Electronic Resource
    Electronic Resource
    Structural analysis of fetal rat lung development (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 234 (1992), S. 399-418 
    Details
    ISSN: 0003-276X
    Keywords: Lung development ; Lung compartments ; Lung parenchyma ; Airways ; Pulmonary vasculature ; Cellular differentiation ; Morphometry ; Reference space ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The primary aim of this morphological investigation was to elaborate a concept allowing us to coherently define reference spaces for morphometric analysis of fetal lung development. Beyond this quantitative goal, morphological analysis of cell types, definition of compartments, and reflection about the prospective fate of their constitutents provided per se new insights into the developmental processes.Lungs of rat fetuses aged 17-23 days and newborns aged 20 hours were fixed with an osmium tetroxide and glutaraldehyde mixture and their volume determined. Left lungs were embedded in Epon and investigated by light and electron microscopy. The right lung of one animal per group was embedded in methacrylate and step sections obtained to precisely locate the airways within the mesenchyme.The various cell types, their topographical relationships, and their morphological alterations with ongoing development were analyzed with regard to their prospective potentials of differentiation.The developing lung could be partitioned into four zones further subdivided into defined compartments. Zone I forms a superficial mantle around the lobes and the future acini. Consisting of primitive mesenchymal cells, it represents a zone of growth which disappears with the onset of the saccular stage. Zone II is mainly a zone of differentiation. Its interstitium stains intensely due to a dense population of dark cells. Up to gestational day 19, zone II contains future conductive airways with their vessels. After day 21, it comprises the whole prospective gas exchange region. Zones III and IV contain the elements of the airway tree and vascular system, zone IV corresponding to the most proximal generations with an adventitial layer. For all differentiation processes, a centrifugal directionality is manifested.© Willey-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092340310
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