scholarly journals Differences in basement membrane-associated microdomains of type I and type II pneumocytes in the rat and rabbit lung.

1984 ◽  
Vol 32 (8) ◽  
pp. 827-833 ◽  
Author(s):  
P L Sannes
Keyword(s):  
Basement Membrane ◽  
Basement Membranes ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Sulfate Ester ◽  
Pulmonary Alveoli ◽  
Type I Cells ◽  
Type Ii Pneumocytes ◽  
I Cells

The basement membrane-associated microdomains of type I pneumocytes in rat and rabbit pulmonary alveoli were found to be uniquely different from those of type II pneumocytes in the specific distribution of cytochemically detectable sulfate esters as demonstrated with the high iron diamine (HID) technique at the electron microscopic level. Aldehyde-fixed frozen or Vibratome sections of neonatal and adult lungs were treated with a mixture of the meta and para isomers of N,N-dimethyl-phenylenediamine-HCl in the presence of ferric chloride, which at low pH (1.0) has been previously shown to be highly specific for sulfate esters of glycosaminoglycans and glycoproteins. Reaction product was subsequently enhanced with a thiocarbohydrazide-silver proteinate, postembedding sequence for electron microscopy. Samples of lung parenchyma treated in this fashion were observed to have discrete, electron-dense silver grains associated with the various microanatomical components of pulmonary basement membranes. In the region of the alveolar basement membrane, the lamina rara externa associated with type I cells was observed to contain an abundance of regularly disposed, cytochemically detectable sulfate esters, while the lamina densa and lamina rara interna were diffusely and sparsely reactive by comparison. Quantitatively, 62% of all reactive sites found in the basement membrane region of type I cells were localized in the lamina rara externa. By contrast, the lamina rara externa of type II cells had less than half as many reactive foci indicative of sulfate esters as the same region of type I cell basement membranes. HID-reactive sulfate esters were found evenly distributed within the laminae associated with the basement membrane of type II cells. This cytochemically detectable difference in the sulfate ester composition of basement membrane-associated sulfate ester composition of basement membrane-associated microdomains of type I compared with that of type II pneumocytes may be highly significant when considering known patterns of epithelial renewal in pulmonary alveoli. Since type II cells are known to divide and either remain type II cells or differentiate into type I cells, regional differences in the molecular composition of the alveolar basement membranes and their associated structures may be key determinants of cell-specific processes of cytodifferentiation in the pulmonary alveolus.

scholarly journals ULTRASTRUCTURE OF THE CAROTID BODY

1966 ◽  
Vol 30 (3) ◽  
pp. 563-578 ◽  
Author(s):  
T. J. Biscoe ◽  
W. E. Stehbens
Keyword(s):  
Blood Vessels ◽  
Schwann Cells ◽  
Carotid Body ◽  
Nerve Fibers ◽  
Nerve Endings ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Type I Cells ◽  
I Cells

An electron microscope investigation was made of the carotid body in the cat and the rabbit. In thin-walled blood vessels the endothelium was fenestrated. Larger vessels were surrounded by a layer of smooth muscle fibers. Among the numerous blood vessels lay groups of cells of two types covered by basement membranes. Aggregates of Type I cells were invested by Type II cells, though occasionally cytoplasmic extensions were covered by basement membrane only. Type I cells contained many electron-opaque cored vesicles (350 to 1900 A in diameter) resembling those in endocrine secretory cells. Type II cells covered nerve endings terminating on Type I cells and enclosed nerve fibers in much the same manner as Schwann cells. The nerve endings contained numerous microvesicles (∼500 A in diameter), mitochondria, glycogen granules, and a few electron-opaque cored vesicles. Junctions between nerve endings and Type I cells were associated with regions of increased density in both intercellular spaces and the adjoining cytoplasm. Cilia of the 9 + 0 fibril pattern were observed in Type I and Type II cells and pericytes. Nonmyelinated nerve fibers, often containing microvesicles, mitochondria, and a few electron-opaque cored vesicles (650 to 1000 A in diameter) were present in Schwann cells, many of which were situated close to blood vessels Ganglion cells near the periphery of the gland, fibrocytes, and segments of unidentified cells were also seen. It was concluded that, according to present concepts of the structure of nerve endings, those endings related to Type I cells could be efferent or afferent.

Effects of oligohydramnios on lung growth and maturation in the fetal rat

2002 ◽  
Vol 282 (3) ◽  
pp. L431-L439 ◽  
Author(s):  
Joseph A. Kitterman ◽  
Cheryl J. Chapin ◽  
Jeff N. Vanderbilt ◽  
Nicolas F. M. Porta ◽  
Louis M. Scavo ◽  
...  
Keyword(s):  
Fetal Lung ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lung Growth ◽  
Type I Cells ◽  
Fetal Lung Development ◽  
Fetal Rat ◽  
I Cells

Oligohydramnios (OH) retards fetal lung growth by producing less lung distension than normal. To examine effects of decreased distension on fetal lung development, we produced OH in rats by puncture of uterus and fetal membranes at 16 days of gestation; fetuses were delivered at 21 or 22 days of gestation. Controls were position-matched littermates in the opposite uterine horn. OH lungs had lower weights and less DNA, protein, and water, but no differences in saturated phosphatidylcholine, surfactant proteins (SP)-A and -B, and mRNA for SP-A, -B, -C, and -D. To evaluate effects on epithelial differentiation, we used RTI40 and RTII70, proteins specific in lung to luminal surfaces of alveolar type I and II cells, respectively. At 22 days of gestation, OH lungs had less RTI40 mRNA ( P < 0.05) and protein ( P < 0.001), but RTII70 did not differ from controls. With OH, type I cells (in proportion to type II cells) covered less distal air space perimeter ( P < 0.01). We conclude that OH, which retards lung growth, has little effect on surfactant and impedes formation of type I cells relative to type II cells.

A Study of the Enteric Plexuses in Some Amphibians

1951 ◽  
Vol s3-92 (17) ◽  
pp. 55-77
Author(s):  
MARGARET GUNN
Keyword(s):  
Myenteric Plexus ◽  
Proximal Part ◽  
Nerve Cells ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Nerve Fibres ◽  
Type I Cells ◽  
Splanchnic Nerves ◽  
I Cells

1. The extrinsic nerve-supply to the gut in the frog (Rana temporaria) is contained in the vagus and splanchnic nerves--both of which appear to contain parasympathetic and sympathetic fibres. 2. The vagus supplies the gut from the proximal part of the oesophagus to the most proximal part of the intestine. The splanchnic nerves supply the gut from the oesophagus to the rectum. 3. No vagal fibres accompany the splanchnic nerves. 4. A possible explanation is given for the variable effects produced on stimulation of the extrinsic nerves supplying the gut. 5. A plexus of nerve-fibres is present i n the submucosa which probably corresponds to Meissner's plexus of mammals, but no nerve-cells are present. 6. In the myenteric plexus the nerve-cells are commonly grouped int o ganglia in the oesophagus and stomach, but in theintestine the nerve-cells are fairly evenly distributed, distinct ganglia not being present. 7. Cells of three types have been found corresponding to Dogiel's three types. Type I cells are of two varieties: (a) large, strongly argyrophi l cells which are multi-polar possessing numerous short dendrites and a very prominent axon; (b)smaller cells having a prominent axon and often unipolar. Type I cells are enclosed in capsules. Type II cells are small multipolar cells with long dendrites. Type III cells are small multipolar cells with shorter dendrites and an axon bearing no collaterals. 8. Cells in the oesophagus and stomach are entirely of Type I. In the intestine these cells are present in fairly large numbers at the most proximal end, but throughout the rest of the intestine they only occur commonly close to the attachment of the mesentery, where they are found singly and fairly evenly spaced. 9. Cells of Types II and III occur only in the myenteric plexus of the intestine, where they are distributed fairly evenly, not forming distinct ganglia. 10. It is suggested that the Type II and III cells formed the original autonomic nerve plexus of the gut, the Type II cells being motor and the Type III sensory. The Type I cells are the post-ganglionic cells of the parasympathetic system and are an additional motor contribution to the plexus. 11. The endings of th e pre-ganglionic parasympathetic fibres on the ganglion cells may take any of three forms: (a) pericellular varicose endings which occur on the large variety of Typ e I cell; (b) pericapsular varicose endings which are borne by the smaller variety of Type I cell; and(c) club-shaped endings occurring on the larger Type I cells. 12. The type of synapse formed by the processes of cells of Types II and III consists of the simple endings of their processes on the cell bodies or dendrites of other cells, or the passing contact of their processes with the bodies of other cells. 13. Fine varicose fibrils have been observed on the surface of muscle-cells. These are presumably the distal ends of the cell processes and sympathetic fibres which form the motor endings. 14. The types of sensory endings which have been found are: (a) typical sensory varicose endings spread out in the submucosa of the oesophagus and rectum; those in the oesophagus originating from vagal fibres; and (b) Pacinian corpuscle in the sub-mucosa of the intestine. 15. The ‘interstitial cells of Cajal’ form an apparently anastomosing network in the gut-wall which appears to be distinct from the anastomosing Schwann plasmodium which covers the nerve-fibres.

scholarly journals UTP regulation of ion transport in alveolar epithelial cells involves distinct mechanisms

2009 ◽  
Vol 297 (3) ◽  
pp. L439-L454 ◽  
Author(s):  
Chuanxiu Yang ◽  
Lijing Su ◽  
Yang Wang ◽  
Lin Liu
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Alveolar Epithelial Cells ◽  
Alveolar Type ◽  
Channel Blockers ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Type I Cells ◽  
I Cells

UTP is known to regulate alveolar fluid clearance. However, the relative contribution of alveolar type I cells and type II cells to this process is unknown. In this study, we investigated the effects of UTP on ion transport in type I-like cell (AEC I) and type II-like cell (AEC II) monolayers. Luminal treatment of cell monolayers with UTP increased short-circuit current ( Isc) of AEC II but decreased Isc of AEC I. The Cl− channel blockers NPPB and DIDS inhibited the UTP-induced changes in Isc (Δ Isc) in both types of cells. Amiloride, an inhibitor of epithelial Na+ channels (ENaC), abolished the UTP-induced Δ Isc in AEC I, but not in AEC II. The general blocker of K+ channels, BaCl2, eliminated the UTP-induced Δ Isc in AEC II, but not in AEC I. The intermediate conductance (IKCa) blocker, clofilium, also blocked the UTP effect in AEC II. The signal transduction pathways mediated by UTP were the same in AEC I and AEC II. Furthermore, UTP increased Cl− secretion in AEC II and Cl− absorption in AEC I. Our results suggest that UTP induces opposite changes in Isc in AEC I and AEC II, likely due to the reversed Cl− flux and different contributions of ENaC and IKCa. Our results further imply a new concept that type II cells contribute to UTP-induced fluid secretion and type I cells contribute to UTP-induced fluid absorption in alveoli.

Low permeabilities of MDCK cell monolayers: a model barrier epithelium

1997 ◽  
Vol 273 (1) ◽  
pp. F67-F75 ◽  
Author(s):  
J. P. Lavelle ◽  
H. O. Negrete ◽  
P. A. Poland ◽  
C. L. Kinlough ◽  
S. D. Meyers ◽  
...  
Keyword(s):  
Mdck Cells ◽  
Collecting Duct ◽  
Type I ◽  
Thick Ascending Limb ◽  
Type Ii Cells ◽  
Type Ii ◽  
Type I Cells ◽  
A Cell ◽  
Apical Membranes ◽  
I Cells

Barrier epithelia such as the renal collecting duct (in the absence of antidiuretic hormone) and thick ascending limb, as well as the stomach and mammalian bladder, exhibit extremely low permeabilities to water and small nonelectrolytes. A cell culture model of such epithelia is needed to determine how the structure of barrier apical membranes reduce permeability and how such membranes may be generated and maintained. In the present studies, the transepithelial electrical resistance and isotopic water and urea fluxes were measured for Madin-Darby canine kidney (MDCK) type I and type II cells, as well as type I cells expressing the mucin protein, MUC1, in their apical membranes. Although earlier studies had found the unstirred layer effects too great to permit measurement of transepithelial permeabilities, use of ultrathin semipermeable supports in this study overcame this difficulty. Apical membrane diffusive water permeabilities were 1.8 +/- 0.4 x 10(-4) cm/s and 3.5 +/- 0.5 x 10(-4) cm/s in MDCK type I and type II cells, respectively, at 20 degrees C. Urea permeability in type I cells at the same temperature was 6.0 +/- 0.9 x 10(-6) cm/s. These values resemble those of other barrier epithelial apical membranes, either isolated or in intact epithelia, and the water permeability values are far below those of other epithelial cells in culture. Transfection of MDCK type I cells with the major human urinary epithelial mucin, MUC1, led to abundant expression of the fully glycosylated form of the protein on immunoblots, and flow cytometry revealed that virtually all the cells expressed the protein. However, MUC1 had no effect on water or urea permeabilities. In conclusion, MDCK cells grown on semipermeable supports form a model barrier epithelium. Abundant expression of mucins does not alter the permeability properties of these cells.

scholarly journals CD44high alveolar type II cells show stem cell properties during steady-state alveolar homeostasis

2017 ◽  
Vol 313 (1) ◽  
pp. L41-L51 ◽  
Author(s):  
Qian Chen ◽  
Varsha Suresh Kumar ◽  
Johanna Finn ◽  
Dianhua Jiang ◽  
Jiurong Liang ◽  
...  
Keyword(s):  
Alveolar Epithelium ◽  
Cell Subpopulation ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Cell Surface Molecule ◽  
Type I Cells ◽  
Blood Exchange ◽  
I Cells

The alveolar epithelium is composed of type I cells covering most of the gas-blood exchange surface and type II cells secreting surfactant that lowers surface tension of alveoli to prevent alveolar collapse. Here, we have identified a subgroup of type II cells expressing a higher level of cell surface molecule CD44 (CD44high type II cells) that composed ~3% of total type II cells in 5–10-wk-old mice. These cells were preferentially apposed to lung capillaries. They displayed a higher proliferation rate and augmented differentiation capacity into type I cells and the ability to form alveolar organoids compared with CD44low type II cells. Moreover, in aged mice, 18–24 mo old, the percentage of CD44high type II cells among all type II cells was increased, but these cells showed decreased progenitor properties. Thus CD44high type II cells likely represent a type II cell subpopulation important for constitutive regulation of alveolar homeostasis.

Type II epithelial cells are critical target for hyperoxia-mediated impairment of postnatal lung development

2006 ◽  
Vol 291 (5) ◽  
pp. L1101-L1111 ◽  
Author(s):  
Min Yee ◽  
Peter F. Vitiello ◽  
Jason M. Roper ◽  
Rhonda J. Staversky ◽  
Terry W. Wright ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cells ◽  
Lung Development ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Newborn Mice ◽  
Type I Cells ◽  
Type Ii Cell ◽  
I Cells

Type II epithelial cells are essential for lung development and remodeling, as they are precursors for type I cells and can produce vascular mitogens. Although type II cell proliferation takes place after hyperoxia, it is unclear why alveolar remodeling occurs normally in adults whereas it is permanently disrupted in newborns. Using a line of transgenic mice whose type II cells could be identified by their expression of enhanced green fluorescent protein and endogenous expression of surfactant proteins, we investigated the age-dependent effects of hyperoxia on type II cell proliferation and alveolar repair. In adult mice, type II cell proliferation was low during room air and hyperoxia exposure but increased during recovery in room air and then declined to control levels by day 7. Eight weeks later, type II cell number and alveolar compliance were indistinguishable from those in room air controls. In newborn mice, type II cell proliferation markedly increased between birth and postnatal day 7 before declining by postnatal day 14. Exposure to hyperoxia between postnatal days 1 and 4 inhibited type II cell proliferation, which resumed during recovery and was aberrantly elevated on postnatal day 14. Eight weeks later, recovered mice had 70% fewer type II cells and 30% increased lung compliance compared with control animals. Recovered mice also had higher levels of T1α, a protein expressed by type I cells, with minimal changes detected in genes expressed by vascular cells. These data suggest that perinatal hyperoxia adversely affects alveolar development by disrupting the proper timing of type II cell proliferation and differentiation into type I cells.

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