Morphological Changes in Rat Vestibular System Following Weightlessness

1993 ◽  
Vol 3 (3) ◽  
pp. 241-251
Author(s):  
Muriel D. Ross
Keyword(s):  
Hair Cells ◽  
Space Shuttle ◽  
Morphological Changes ◽  
Distributed Processing ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Ribbon Synapses ◽  
Gravity Receptors ◽  
I Cells

Mammalian gravity receptors (maculas) are morphologically organized for weighted, parallel distributed processing of information. There are two basic circuits: 1) highly channeled, type I cell to calyx; and 2) distributed modifying, type II cells to calyces and processes. The latter circuit should be the more adaptable since it modifies final output. To test this hypothesis, rats were flown in microgravity for 9 days aboard a space shuttle and euthanized shortly after landing. Hair cells and ribbon synapses from maculas of 3 flight and 3 ground control rats were studied ultrastructurally in blocks of 50 serial sections. Synapses increased by approximately 41% in type I cells and by approximately 55% in type II cells in flight animals. There was a shift toward the spherular form of ribbon synapse in both types of hair cells in flight animals (P ⩽ 0.0001), a near doubling of pairs in the flight rats (P ⩽ 0.0001), and an increase, by a factor of 12, in groups of synapses in type II cells (P ⩽ 0.0001). Current findings tend to support the stated hypothesis and indicate that mature utricular hair cells retain synaptic plasticity, permitting adaptation to an altered gravitational environment.

Voltage-Gated Calcium Channel Currents in Type I and Type II Hair Cells Isolated From the Rat Crista

2003 ◽  
Vol 90 (1) ◽  
pp. 155-164 ◽  
Author(s):  
Hong Bao ◽  
Weng Hoe Wong ◽  
Jay M. Goldberg ◽  
Ruth Anne Eatock
Keyword(s):  
Hair Cells ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Α Subunit ◽  
Voltage Gated ◽  
Type I Cells ◽  
Channel Currents ◽  
I Cells

When studied in vitro, type I hair cells in amniote vestibular organs have a large, negatively activating K+ conductance. In type II hair cells, as in nonvestibular hair cells, outwardly rectifying K+ conductances are smaller and more positively activating. As a result, type I cells have more negative resting potentials and smaller input resistances than do type II cells; large inward currents fail to depolarize type I cells above –60 mV. In nonvestibular hair cells, afferent transmission is mediated by voltage-gated Ca2+ channels that activate positive to –60 mV. We investigated whether Ca2+ channels in type I cells activate more negatively so that quantal transmission can occur near the reported resting potentials. We used the perforated patch method to record Ca2+ channel currents from type I and type II hair cells isolated from the rat anterior crista (postnatal days 4–20). The activation range of the Ca2+ currents of type I hair cells differed only slightly from that of type II cells or nonvestibular hair cells. In 5 mM external Ca2+, currents in type I and type II cells were half-maximal at –41.1 ± 0.5 (SE) mV ( n = 10) and –37.2 ± 0.2 mV ( n = 10), respectively. In physiological external Ca2+ (1.3 mM), currents in type I cells were half-maximal at –46 ± 1 mV ( n = 8) and just 1% of maximal at –72 mV. These results lend credence to suggestions that type I cells have more positive resting potentials in vivo, possibly through K+ accumulation in the synaptic cleft or inhibition of the large K+ conductance. Ca2+ channel kinetics were also unremarkable; in both type I and type II cells, the currents activated and deactivated rapidly and inactivated only slowly and modestly even at large depolarizations. The Ca2+ current included an L-type component with relatively low sensitivity to dihydropyridine antagonists, consistent with the α subunit being CaV1.3 (α1D). Rat vestibular epithelia and ganglia were probed for L-type α-subunit expression with the reverse transcription-polymerase chain reaction. The epithelia expressed CaV1.3 and the ganglia expressed CaV1.2 (α1C).

scholarly journals Mechanical stretch activates piezo1 in caveolae of alveolar type I cells to trigger ATP release and paracrine stimulation of surfactant secretion from alveolar type II cells

2020 ◽  
Vol 34 (9) ◽  
pp. 12785-12804 ◽  
Author(s):  
Kathrin Diem ◽  
Michael Fauler ◽  
Giorgio Fois ◽  
Andreas Hellmann ◽  
Natalie Winokurow ◽  
...  
Keyword(s):  
Atp Release ◽  
Mechanical Stretch ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Surfactant Secretion ◽  
I Cells ◽  
Stimulation Of

scholarly journals Transitional human alveolar type II epithelial cells suppress extracellular matrix and growth factor gene expression in lung fibroblasts

2019 ◽  
Vol 317 (2) ◽  
pp. L283-L294 ◽  
Author(s):  
Kelly A. Correll ◽  
Karen E. Edeen ◽  
Rachel L. Zemans ◽  
Elizabeth F. Redente ◽  
Karina A. Serban ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Surfactant Protein ◽  
Lung Fibroblasts ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
I Cells

Epithelial-fibroblast interactions are thought to be very important in the adult lung in response to injury, but the specifics of these interactions are not well defined. We developed coculture systems to define the interactions of adult human alveolar epithelial cells with lung fibroblasts. Alveolar type II cells cultured on floating collagen gels reduced the expression of type 1 collagen (COL1A1) and α-smooth muscle actin (ACTA2) in fibroblasts. They also reduced fibroblast expression of hepatocyte growth factor (HGF), fibroblast growth factor 7 (FGF7, KGF), and FGF10. When type II cells were cultured at an air-liquid interface to maintain high levels of surfactant protein expression, this inhibitory activity was lost. When type II cells were cultured on collagen-coated tissue culture wells to reduce surfactant protein expression further and increase the expression of some type I cell markers, the epithelial cells suppressed transforming growth factor-β (TGF-β)-stimulated ACTA2 and connective tissue growth factor (CTGF) expression in lung fibroblasts. Our results suggest that transitional alveolar type II cells and likely type I cells but not fully differentiated type II cells inhibit matrix and growth factor expression in fibroblasts. These cells express markers of both type II cells and type I cells. This is probably a normal homeostatic mechanism to inhibit the fibrotic response in the resolution phase of wound healing. Defining how transitional type II cells convert activated fibroblasts into a quiescent state and inhibit the effects of TGF-β may provide another approach to limiting the development of fibrosis after alveolar injury.

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.

scholarly journals Lectin binding patterns to terminal sugars of rat lung alveolar epithelial cells.

1990 ◽  
Vol 38 (2) ◽  
pp. 233-244 ◽  
Author(s):  
D J Taatjes ◽  
L A Barcomb ◽  
K O Leslie ◽  
R B Low
Keyword(s):  
Epithelial Cells ◽  
Lectin Binding ◽  
Alveolar Epithelial Cells ◽  
Gold Complex ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Rat Lung ◽  
Alveolar Epithelial ◽  
I Cells

We used post-embedding cytochemical techniques to investigate the lectin binding profiles of rat lung alveolar epithelial cells. Sections from rat lung embedded in the hydrophilic resin Lowicryl K4M were incubated either directly with a lectin-gold complex or with an unlabeled lectin followed by a specific glycoprotein-gold complex. The binding patterns of the five lectins used could be divided into three categories according to their reactivity with alveolar epithelial cells: (a) the Limax flavus lectin and Ricinus communis I lectin bound to both type I and type II cell plasma membranes; (b) the Helix pomatia lectin and Sambucus nigra L. lectin bound to type II but not type I cells; and (c) the Erythrina cristagalli lectin reacted with type I cells but was unreactive with type II cells. The specificity of staining was assessed by control experiments, including pre-absorption of the lectins with various oligosaccharides and enzymatic pre-treatment of sections with highly purified glycosidases to remove specific sugar residues. The results demonstrate that these lectins can be used to distinguish between type I and type II cells and would therefore be useful probes for investigating cell dynamics during lung development and remodeling.

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.

Vestibular Type I and Type II Hair Cells. 1: Morphometric Identification in the Pigeon and Gerbil

1997 ◽  
Vol 7 (5) ◽  
pp. 393-406
Author(s):  
Anthony J. Ricci ◽  
Katherine J. Rennie ◽  
Stephen L. Cochran ◽  
Golda A. Kevetter ◽  
Manning J. Correia
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Cell Types ◽  
Type I ◽  
Type Ii ◽  
Body Width ◽  
Fixed Tissue ◽  
Neck Width ◽  
I Cells ◽  
Plate Width

Classically, type I and type II vestibular hair cells have been defined by their afferent innervation patterns. Little quantitative information exists on the intrinsic morphometric differences between hair cell types. Data presented here define a quantitative method for distinguishing hair cell types based on the morphometric properties of the hair cell’s neck region. The method is based initially on fixed histological sections, where hair cell types were identified by innervation pattern, type I cells having an afferent calyx. Cells were viewed using light microscopy, images were digitized, and measurements were made of the cell body width, the cuticular plate width, and the neck width. A plot of the ratio of the neck width to cuticular plate width (NPR) versus the ratio of the neck width to the body width (NBR) established four quadrants based on the best separation of type I and type II hair cells. The combination of the two variables made the accuracy of predicting either type I or type II hair cells greater than 90%. Statistical cluster analysis confirmed the quadrant separation. Similar analysis was performed on dissociated hair cells from semicircular canal, utricle, and lagena, giving results statistically similar to those of the fixed tissue. Additional comparisons were made between fixed tissue and isolated hair cells as well as across species (pigeon and gerbil) and between end organs (semicircular canal, utricle, and lagena). In each case, the same morphometric boundaries could be used to establish four quadrants, where quadrant 1 was predominantly type I cells and quadrant 3 was almost exclusively type II hair cells. The quadrant separations were confirmed statistically by cluster analysis. These data demonstrate that there are intrinsic morphometric differences between type I and type II hair cells and that these differences can be maintained when the hair cells are dissociated from their respective epithelia.

Sign in / Sign up

Export Citation Format

Share Document