Exclusion of dextrans by meshworks of collagenous fibres.

Insoluble collagen from human dermis was equilibrated in a physiological medium with mixtures of 3H2O and fluorescein-conjugated dextrans of different molecular weights. Dextrans of mol.wts. greater than 10(5) were excluded from a volume of 3.82+/-0.87 ml(S.D.) per g of collagen; dextrans of lower molecular weight occupied a larger volume. The apparent excluded volume was proportional to the weight of the collagen. Dansylated albumin behaved similarly to dextran; the polymeric collagen from rat skin exhibited a much larger excluded volume than the insoluble collagen. These results indicated that the volume available to the plasma proteins in human dermis was limited by insoluble collagen as well as by the glycosaminoglycans of the tissue.     

Characterization of collagenous meshworks by volume exclusion of dextrans.

The volumes from which 3H-labelled dextrans are excluded by dermal collagenous fibres were calculated by dilution of dextran probes. Five dextrans, of average Stokes' radii 1.72, 2.53, 3.92, 4.54 and 14.24nm, were investigated at concentrations between 0.1 and 3% (w/w). The excluded volume was dependent on dextran concentration only for the two smaller probes. The largest dextran was shown not to bind to the fibres. A plot of the square root of excluded volume against Stokes' radius was linear for the four smallest dextrans, corresponding to the predictions of Ogston's [(1958) Trans. Faraday Soc. 54, 1754--1757] rod-and-sphere model of fibrous exclusion, and suggesting that dextrans of Stokes' radius between 1.72 and 4.54 nm were excluded by a cylindrical solid fibre of radius 2.90 +/- 0.72 nm. Larger molecules were excluded by a structure of much greater size, since the volume exclusion for the largest dextran was only slightly greater than that of the dextran less than one-third its radius. The excluded volume of 3H2O fell slightly below the line describing the dextran data, indicating that water had access to most of the volume not occupied by the collagenous fibres.     

Collagen of slow twitch and fast twitch muscle fibres in different types of rat skeletal muscle

The appearance of collagen around individual fast twitch (FT) and slow twitch (ST) muscle fibres was investigated in skeletal muscles with different contractile properties using endurance trained and untrained rats as experimental animals. The collagenous connective tissue was analyzed by measuring hydroxyproline biochemically and by staining collagenous material histochemically in M. soleus (MS), M. rectus femoris (MRF), and M. gastrocnemius (MG). The concentration of hydroxyproline in the ST fibres dissected from MS (2.72 +/- 0.35 micrograms X mg-1 d.w.) was significantly higher than that of the FT fibres dissected from MRF (1.52 +/- 0.33 micrograms X mg-1 d.w.). Similarly, the concentration of hydroxyproline was higher in ST (2.54 +/- 0.51 micrograms X mg-1 d.w.) than in FT fibres (1.60 +/- 0.43 micrograms X mg-1 d.w.), when the fibres were dissected from the same muscle, MG. Histochemical staining of collagenous material agreed with the biochemical evidence that MS and the slow twitch area of MG are more collagenous than MRF and the fast twitch area of MG both at the level of perimysium and endomysium. The variables were not affected by endurance training. When discussing the role of collagen in the function of skeletal muscle it is suggested that the different functional demands of different skeletal muscles are also reflected in the structure of intramuscular connective tissue, even at the level of endomysial collagen. It is supposed that the known differences in the elastic properties of fast tetanic muscle compared to slow tonic muscle as, e.g., the higher compliance of fast muscle could at least partly be explained in terms of the amount, type, and structure of intramuscular collagen.     

Striae albae: a morphological study on the human skin

Specimens of abdomen skin, comprising alternate areas of striae albae and healthy skin, were removed during surgical lipectomy from multiparous and obese women between the ages of 24 and 53 years. A flattening and thinning of the striae albae surface and the almost complete disappearance of dermal papillae was observed in paraffin and thin sections. The papillary dermis was found to be almost completely replaced by straight bundles of collagen fibres running parallel to the skin surface. Immunofluorescence data revealed in these bundles high positivity for type I collagen. The underlying reticular dermis was also found to contain large densely packed bundles of collagen fibres running parallel to the skin surface. Both papillary and reticular dermis collagen fibres were mainly arranged orthogonally to the main axis of the stria. Furthermore, the density of the collagen fibre bundles and the diameter of the collagen fibrils was found to be greater than that of the clinically healthy skin. A larger number of elastic fibres, which presented an abnormal ultrastructural appearance, were visible in pathological papillary and reticular dermis.     

A hyperelastic biphasic fibre-reinforced model of articular cartilage considering distributed collagen fibre orientations: continuum basis,computational aspects and applications

Cartilage is a multi-phase material composed of fluid and electrolytes (68–85% by wet weight), proteoglycans (5–10% by wet weight), chondrocytes, collagen fibres and other glycoproteins. The solid phase constitutes an isotropic proteoglycan gel and a fibre network of predominantly type II collagen, which provides tensile strength and mechanical stiffness. The same two components control diffusion of the fluid phase, e.g. as visualised by diffusion tensor MRI: (i) the proteoglycan gel (giving a baseline isotropic diffusivity) and (ii) the highly anisotropic collagenous fibre network. We propose a new constitutive model and finite element implementation that focus on the essential load-bearing morphology: an incompressible, poroelastic solid matrix reinforced by an inhomogeneous, dispersed fibre fabric, which is saturated with an incompressible fluid residing in strain-dependent pores of the collagen–proteoglycan solid matrix. The inhomogeneous, dispersed fibre fabric of the solid further influences the fluid permeability, as well as an intrafibrillar portion that cannot be ‘squeezed out’ from the tissue. Using representative numerical examples on the mechanical response of cartilage, we reproduce several features that have been demonstrated experimentally in the cartilage mechanics literature.     

Evidence for a role of hyaluronan in the spacing of fibrils within collagen bundles in rabbit synovium

Synovial hydraulic resistance is vital for the retention of intra-articular fluid, and originates within the matrix of biopolymers in the intercellular gaps. Specific digestion of hyaluronan resulted in a increase in synovial hydraulic permeability from 0.478+/-0.24 microl min(-1) cm H(2)O(-1) in control tissue to 4.561+/-0.40 microl min(-1) cm H(2)O(-1) (mean+/-S.D., n=6 rabbits, P<0.001 t test). To investigate whether hyaluronidase also altered the interstitial ultrastructure, morphometry of hyaluronidase treated synovium was carried out. The most striking novel finding was that hyaluronidase treatment reduced extrafibrillar volume fraction within the synovial collagen bundles from 50.5+/-11.1% to 36.8+/-15.5% (mean+/-S.D., n=6 rabbits, P<0.001, two-way anova). This was accompanied by a reduction in interfibrillar centre to centre spacing from 101+/-11 (control) to 84+/-6 nm (mean+/-S.D.; n=6 rabbits, P<0.001) in enzyme-treated bundles. Individual fibrils showed a small but highly significant reduction in cross-sectional diameter from 76.9+/-6.3 to 72.5+/-6.3 nm (mean+/-S.E.; P<0.001) after hyaluronidase treatment. The findings indicate that hyaluronan chains have a major organisational role within the collagen bundle itself. The trans-synovial pathway comprises bundles and substantial areas of intervening, bundle-free matrix, and it is possible that bundle collapse contributes to a rise in overall permeability by increasing the inter-bundle space.     

Utrastructural interrelationships of collagen fibrillar components in human connective tissue]

The data on structural interconnections between collagenous fibres in the human dermis and periosteum were obtained by means of raster electron microscopy. Collagenous fibres were demonstrated to be connected with each other by means of fine connective fibres situating mainly transversaly towards the main collagenous fibres. Comparing the data obtained with those from the literature, a suggestion was made on the existence, in the connective tissue, of a special connective system composing of peculiar fibrillar structures which maintains dynamic equilibrium in arrangement of collagenous fibres, muscles, vessels, etc. The system of the connective fibres demonstrates a common compositional principle for all the structures mentioned above, but in every case having its peculiarities.     

Interstitial fluid pressure, composition of interstitium, and interstitial exclusion of albumin in hypothyroid rats

Lack of thyroid hormones may affect the composition and structure of the interstitium. Hypothyrosis was induced in rats by thyroidectomy 4-12 wk before the experiments. In hypothyroid rats (n = 16), interstitial fluid pressure measured with micropipettes in hindlimb skin and muscle averaged +0.1 +/- 0.2 and +0.5 +/- 0.2 mmHg, respectively, with corresponding pressures in control rats (n = 16) of -1.5 +/- 0.1 (P < 0.001) and -0.8 +/- 0.1 mmHg (P < 0.001). Interstitial fluid volume, measured as the difference between the distribution volumes of (51)Cr-EDTA and (125)I-labeled BSA, was similar or lower in skin and higher in hypothyroid muscle. Total protein and albumin concentration in plasma and interstitial fluid (isolated from implanted wicks) was lower in hypothyroid compared with control rats. Hyaluronan content (n = 9) in rat hindlimb skin was 2.05 +/- 0.15 and 1.92 +/- 0.09 mg/g dry wt (P > 0.05) in hypothyroid and control rats, respectively, with corresponding content in hindlimb skeletal muscle of 0.35 +/- 0.07 and 0.23 +/- 0. 01 mg/g dry wt (P < 0.01). Interstitial exclusion of albumin in skin and muscle was measured after (125)I-labeled rat serum albumin infusion for 120-168 h with an implanted osmotic pump. Relative excluded volume for albumin (V(e)/V(i)) was calculated as 1 - V(a)/V(i), and averaged 28 and 28% in hindlimb muscle (P > 0.05), 44 and 45% in hindlimb skin (P > 0.05), and 19 and 32% in back skin (P < 0.05) in hypothyroid and control rats, respectively. Albumin mass was higher in back skin in spite of a lower interstitial fluid albumin concentration, a finding explained by a reduced V(e)/V(i) in back skin in hypothyroid rats. These experiments suggest that lack of thyroid hormones in rats changes the interstitial matrix again leading to reduced interstitial compliance and changes in the transcapillary fluid balance.     

Effects of albumin, dextran, and hyaluronidase on pulmonary interstitial conductivity

The fluid conductivity of albumin solutions of various concentrations relative to that of saline was measured in the interstitium surrounding a short segment of a large (1.5- to 3-mm-diam) blood vessel of an isolated rabbit lung of which air spaces and vasculature were filled with silicon rubber. At a constant driving pressure, the flow of the following solutions was measured sequentially: normal saline and albumin solution (3, 5.5, 8, or 15 g/100 ml saline), hyaluronidase solution (0.02 g/100 ml), and albumin solution (same concentration used before hyaluronidase solution). The albumin-to-saline flow ratios averaged 1.00 +/- 0.23 (SD), 1.01 +/- 0.21, 1.32 +/- 0.63, and 1.54 +/- 0.36 for albumin concentrations of 3, 5.5, 8, and 15 g/100 ml, respectively. These ratios were higher than the corresponding values of 0.88, 0.78, 0.72, and 0.5 expected if the flow of albumin solution were to depend only on fluid viscosity. The flow of dextran and hyaluronan solutions was more viscosity dependent than the flow of albumin solutions. The increased flow of albumin solution could be the result of a reduced excluded volume of albumin caused by collagen and glycosaminoglycans with an increased albumin concentration. The flow of hyaluronidase solution was 24 +/- 22 (SD)-fold (n = 36) larger than the flow of albumin solution. Thus hyaluronan was responsible for most of the hydraulic resistance of the interstitium to bulk flow. After its degradation, the flow of albumin solution became more viscosity dependent. The interaction between plasma proteins and glycosaminoglycans in the pulmonary interstitium could serve to enhance clearance of microvascular filtrate, particularly under conditions of large protein leaks.     

Measurement of interstitial albumin in human skeletal muscle and adipose tissue by open-flow microperfusion

The absolute concentration of albumin was measured in the interstitial fluid of subcutaneous adipose tissue and skeletal muscle in six healthy volunteers by combining the method of open-flow microperfusion and the no-net-flux calibration technique. By use of open-flow microperfusion, four macroscopically perforated double lumen catheters were inserted into the tissue regions of interest and constantly perfused. Across the macroscopic perforations of the catheters interstitial fluid was partially recovered in the perfusion fluid. Catheters were perfused with five solutions, each containing different concentrations of albumin. Absolute interstitial albumin concentrations were calculated by applying linear regression analysis to perfusate vs. sampled albumin concentration (no-net-flux calibration technique). Interstitial albumin concentrations were significantly lower (P < 0.0001) in adipose tissue (7.36 g/l; r = 0.99, P < 0.0003; range: 4.3-10.7 g/l) and in skeletal muscle (13.25 g/l; r = 0.99, P < 0.0012; range: 9.7 to 15.7 g/l) compared with the serum concentration (48.9 +/- 0.7 g/l, mean +/- SE, n = 6; range: 46.4-50.4 g/l). Furthermore, interstitial albumin concentrations were significantly higher in skeletal muscle compared with adipose tissue (P < 0.01). The study indicates that open-flow microperfusion allows stable sampling of macromolecules from the interstitial space of peripheral tissue compartments. Moreover, the present data report for the first time in healthy humans in vivo the true albumin concentrations of interstitial fluid of adipose tissue and skeletal muscle.     

Estrone sulfate and sulfatase activity in human breast cancer and endometrial cancer

Estrone sulfate (E1-S) in the serum and tissues of patients with breast cancer or endometrial cancer was measured by a direct radioimmunoassay without hydrolysis. The concentration of E1-S in breast cancer tissue was 1.64 +/- 0.28 ng/g wet wt (+/- SE), lower than in surrounding normal breast tissue (4.46 +/- 1.23). Estradiol-17 beta(E2)/E1-S was higher in endometrial cancer tissue than normal endometrial tissue. Estrone sulfatase activity in breast cancer tissue was 0.81 +/- 0.23 nmol/h/mg protein, higher than in surrounding normal breast tissue (0.35 +/- 0.11). These results suggest that E1-S, which is abundant in the peripheral circulation, is hydrolyzed by sulfatase in breast cancer tissue or endometrial cancer tissue and liberates free estrogens, which may stimulate the growth of these malignant tumors.     

Effect of pressure on circumferential order of adventitial collagen in human brain arteries.

A key factor in the contribution of collagen fibres to tissue mechanics is the alignment of the fibres, which we studied in brain arteries, focussing on alignment changes with distending pressure. Arteries from autopsy were cannulated and fixed at different distending pressures from 0 to 200 mmHg (1 mmHg = 133.32 Pa), alcohol dehydrated, paraffin embedded, sectioned, and stained for birefringent enhancement. The polarized light microscope was set for extinction and fibre orientations were precisely determined at the rotational position of extinction for 200 positions around the artery wall. Results from 22 arterial cross sections revealed, with fixation pressure, a significant but incomplete straightening of collagen (even at 200 mmHg). The mean angular deviation of alignment of fibres was +/- 30 degrees for arteries fixed at zero transmural pressure, which in contrast was +/- 7 degrees for the inner and +/- 13 degrees for the mid-adventitia for arteries fixed at 200 mmHg transmural pressure. We verified on vessels fixed at low pressure, by using a full wave plate in conjunction with the specificity of the interference colours, that the measurements were correct and not confused with angles at 90 degrees to the morphological axis. Alternative tissue processing was done with two arteries fixed at 120 mmHg and processed for frozen sections; the results showed diminished variability in alignment but within the range of measurements for wax embedded tissue. We concluded that the collagen fabric could contribute to the mechanics of brain arteries but that it would be with sinusoidal rather than straightened fibres of collagen.     

A unique cross section through the skin of the dinosaur Psittacosaurus from China showing a complex fibre architecture

This paper reports on a unique preservation of soft tissues in the ventrolateral region of the plant-eating dinosaur Psittacosaurus from the Jehol biota of China. The preservation is of a deep cross section through the dermis, which includes multiple layers of collagenous fibres in excess of 25, among the highest recorded in vertebrates, with a further 15 more layers (poorly preserved) estimated for the entire height of the section. Also, for the first time in a dinosaur two fibre layers parallel to the skin surface are preserved deep within the dermis at the base of the cross section. These fibre layers comprise regularly disposed fibres arranged in left- and right-handed geodesic helices, matching the pattern at the surface and reasonably inferred for the entire section. As noted from the studies on modern-day animals, this fibre structure plays a critical part in the stresses and strains the skin may be subjected to and is ideally suited to providing support and protection. Psittacosaurus gives a remarkable, unprecedented understanding of the dinosaur skin.     

Basic mechanism of three-dimensional collagen fibre transport by fibroblasts

Collagen remodelling by fibroblasts has a crucial role in organizing tissue structures that are essential to motility during wound repair, development and regulation of cell growth. However, the mechanism of collagen fibre movement in three-dimensional (3D) matrices is not understood. Here, we show that fibroblast lamellipodia extend along held collagen fibres, bind, and retract them in a 'hand-over-hand' cycle, involving alpha2beta1 integrin. Wild-type fibroblasts move collagen fibres three to four times farther per cycle than fibroblasts lacking myosin II-B (myosin II-B(-/-)). Similarly, myosin II-B(-/-) fibroblasts contract 3D collagen gels threefold less than controls. On two-dimensional (2D) substrates, however, rates of collagen bead and cell movement are not affected by loss of myosin II-B. Green fluorescent protein (GFP)-tagged myosin II-B, but not II-A, restores normal function in knockout cells and localizes to cell processes, whereas myosin II-A is more centrally located. Additionally, GFP-myosin II-B moves out to the periphery and back during hand-over-hand fibre movement, whereas on 2D collagen, myosin II-B is more centrally distributed. Thus, we suggest that cyclic myosin II-B assembly and contraction in lamellipodia power 3D fibre movements.     

The tensile properties and mode of fracture of elastoidin

The tensile properties and mode of fracture of elastoidin, a collagenous protein fibre from the fins of sharks, were compared with those of rat tail tendon fibres, considered to be a pure form of collagen. Elastoidin fibres were stronger than tendon in the dry state whereas the opposite was observed for fibres tested in the wet state. However, elastoidin was stiffer than tendon whether dry or wet. Scanning electron micrographs of the crosssections and fractured surfaces revealed that elastoidin fibres consisted of fibrils of varying diameter arranged in a lamellar fashion. From the nature of the fractured surfaces, it could be deduced that the primary failure mechanism for elastoidin was probably through a fissuring of the structure.     

Determination of carotenoid and vitamin A concentrations in everted salmonid intestine following exposure to solutions of carotenoid in vitro

Carotenoid (astaxanthin and canthaxanthin) concentrations in everted intestine from rainbow trout (Oncorhynchus mykiss, Walbaum) and Atlantic salmon (Salmo salar, L.) exposed to micelle solubilised carotenoid, have been determined. Following exposure (1 h) to astaxanthin solution (5 mg l(-1)), trout pyloric caeca and mid intestine had higher (P<0.05) mean tissue astaxanthin concentrations (0.50+/-0.08 microg g(-1) and 0.54+/-0.09 microg g(-1), respectively) compared to hind intestine (0.04+/-0.01 microg g(-1); n=11+/-S.E.). Furthermore, the astaxanthin concentration in pyloric caeca (0.50+/-0.08 microg g(-1)) was greater (P<0.05) than that of canthaxanthin (0.11+/-0.01 microg g(-1); n=11, +/-S.E.) when exposed to solutions of similar carotenoid concentration (5.11+/-0.16 mg l(-1) and 5.35+/-0.16 mg l(-1), respectively; n=3+/-S.E.). However, no differences (P>0.05) were recorded between trout and salmon intestinal tissue in terms of astaxanthin concentration following exposure. Trout caeca exposed to astaxanthin solution had significantly (P<0.05) more vitamin A (514.1+/-36.4 microg g(-1)) compared to control tissues (316.5+/-61.7 microg g(-1); n=8+/-S.E.). Vitamin A(1) concentrations in caeca (287.7+/-11.0 microg g(-1)) exposed to astaxanthin solution were significantly higher (P<0.05) compared to controls (174.9+/-26.9 microg g(-1)). However, vitamin A(2) concentrations were not significantly (P>0.05) different (226.3+/-28.2 microg g(-1) and 141.6+/-35.2 microg g(-1), respectively).     

Human lymphedema fluid lipoproteins: particle size, cholesterol and apolipoprotein distributions, and electron microscopic structure

The concentration of cholesterol, apolipoproteins A-I, B, and E has been determined in lymphedema fluid from nine patients with chronic primary lymphedema. The concentrations were: 38.14 +/- 21.06 mg/dl for cholesterol, 15.6 +/- 6.17 mg/dl for apolipoprotein A-I, 7.5 +/- 2.8 mg/dl for apolipoprotein B, and 1.87 +/- 0.50 mg/dl for apolipoprotein E. These values represent 23%, 12%, 6%, and 38% of plasma concentrations, respectively. The ratio of esterified to unesterified cholesterol in lymphedema fluid was 1.46 +/- 0.45. Lipoproteins of lymphedema fluid were fractionated according to particle size by gradient gel electrophoresis and by exclusion chromatography. Gradient gel electrophoresis showed that a majority of high density lipoproteins (HDL) of lymphedema fluid were larger than ferritin (mol wt 440,000) and smaller than low density lipoproteins (LDL); several discrete subpopulations could be seen with the large HDL region. Fractionation by exclusion chromatography showed that more than 25% of apolipoprotein A-I and all of apolipoprotein E in lymphedema fluid was associated with particles larger than plasma HDL2. Apolipoprotein A-I also eluted in fractions that contained particles the size of or smaller than albumin. Isolation of lipoproteins by sequential ultracentrifugation showed that less than 25% of lymphedema fluid cholesterol was associated with apolipoprotein B. The majority of apolipoprotein A-containing lipoproteins of lymphedema fluid were less dense than those in plasma. Ultracentrifugally separated fractions of lipoproteins were examined by electron microscopy. The fraction d less than 1.019 g/ml contained little material, while fraction d 1.019-1.063 g/ml contained two types of particles: round particles 17-26 nm in diameter and square-packing particles 13-17 nm on a side. Fractions d 1.063-1.085 g/ml had extensive arrays of square-packing particles 13-14 nm in size. Fractions d 1.085-1.11 g/ml and fractions d 1.11-1.21 g/ml contained round HDL, 12-13 nm diameter and 10 nm diameter, respectively. Discoidal particles were observed infrequently.     

Collagen types I, III, and V in human embryonic and fetal skin

The dermis of human skin develops embryonically from lateral plate mesoderm and is established in an adult-like pattern by the end of the first trimester of gestation. In this study the structure, biochemistry, and immunocytochemistry of collagenous matrix in embryonic and fetal dermis during the period of 5 to 26 weeks of gestation was investigated. The dermis at five weeks contains fine, individual collagen fibrils draped over the surfaces of mesenchymal cells. With increasing age, collagen matrix increases in abundance in the extracellular space. The size of fibril diameters increases, and greater numbers of fibrils associate into fiber bundles. By 15 weeks, papillary and reticular regions are recognized. Larger-diameter fibrils, larger fibers, denser accumulations of collagen, and fewer cells distinguish the deeper reticular region from the finer, more cellular papillary region located beneath the epidermis. The distribution of collagen types I, III, and V were studied at the light microscope level by immunoperoxidase staining and at the ultrastructural level by transmission (TEM) and scanning electron microscopy (SEM) with immunogold labeling. By immunoperoxidase, types I and III were found to be evenly distributed, regardless of fetal age, throughout the dermal and subdermal connective tissue with an intensification of staining at the dermal-epidermal junction (DEJ). Staining for types III and V collagen was concentrated around blood vessels. Type V collagen was also localized in basal and periderm cells of the epidermis. By immuno-SEM, types I and III were found associated with collagen fibrils, and type V was localized to dermal cell surfaces and to a more limited extent with fibrils. The results of biochemical analyses for relative amounts of types I, III, and V collagen in fetal skin extracts were consistent with immunoperoxidase data. Type I collagen was 70-75%, type III collagen was 18-21%, and type V was 6-8% of the total of these collagens at all gestational ages tested, compared to 85-90% type I, 8-11% type III, and 2-4% type V in adult skin. The enrichment of both types III and V collagen in fetal skin may reflect in part the proportion of vessel- and nerve-associated collagen versus dermal fibrillar collagen. The accumulation of dermal fibrillar collagen with increasing age would enhance the estimated proportion of type I collagen, even though the ratios of type III to I in dermal collagen fibrils may be similar at all ages.     

Evidence of denticles and attachment fibres in the superficial layer of scales in two fishes: Carassius auratus and Cyprinus carpio (Cyprinidae, Teleostei)

An attempt is made to clarify the mechanisms of the scale anchorage in two Cyprinidae, the goldfish and the carp. Scanning and transmission electron microscope investigations
revealed the presence of two different structures, denticles and collagen fibre bundles involved in the anchoring processes. These strucures are located on the upper part of the
scales. Denticles form minute processes on the circuli of the anterior areas of the scales. Collagen fibre bundles arise from the superficial layer connecting the scale to the overlying dermis. These fibre bundles show structural similarities with the Sharpey's fibres and are named Sharpey-fibre-like bundles. Such fibres of attachment, not previously reported, can be considered as usual anchoring structures in fish scales.     

Regional differences in interstitial fluid albumin concentration in edematous lamb lungs.

We have determined regional lung interstitial fluid albumin concentration in lambs with hydrostatic pulmonary edema and correlated it with lung lymph and plasma albumin concentrations. In anesthetized lambs, we raised left atrial pressure to 25-30 cmH2O by obstructing the aorta and volume overloading the lambs with infusions of Ringer lactate solution (group I, n = 10) or sheep's blood (group II, n = 9). We measured lung lymph flow and concentrations of total protein and albumin in plasma and lymph. With micropipettes we also collected interstitial fluid from interlobular septal pools and peribronchial, periarterial, and perivenous liquid cuffs near the hilum for measurement of albumin concentration by the gel immunoelectrophoresis method. In both groups, lung lymph flow increased with left atrial hypertension, and the ratio of lymph to plasma protein concentration fell. For group I, plasma and lymph albumin concentrations during the phase of hydrostatic edema were 1.97 +/- 0.49 and 1.15 +/- 0.36, respectively; for group II, they were 3.77 +/- 0.42 and 2.43 +/- 0.39 g/dl, respectively. Lung wet-to-dry weight ratio averaged 6.0 in both groups. Albumin concentration was always lower in interstitial fluid than in plasma. In both groups, albumin concentration was similar in periarterial and peribronchial fluid cuffs (group I 1.19 +/- 0.6 and 1.36 +/- 0.79 g/dl, respectively; group II 2.87 +/- 1.05 and 2.33 +/- 0.58 g/dl, respectively) but was always greater than that in perivenous and interlobular septal pools (group I 0.61 +/- 0.21 and 0.67 +/- 0.23 g/dl, respectively; group II 1.76 +/- 0.49 and 1.55 +/- 0.52 g/dl, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)