Electron microscopic observations on pulmonary connective tissue stained by Ruthenium Red

Unique structural features that influence neutrophil emigration into the lung

Neutrophil emigration in the lung differs substantially from that in systemic vascular beds where extravasation occurs primarily through postcapillary venules. Migration into the alveolus occurs directly from alveolar capillaries and appears to progress through a sequence of steps uniquely influenced by the cellular anatomy and organization of the alveolar wall. The cascade of adhesive and stimulatory events so critical to the extravasation of neutrophils from postcapillary venules in many tissues is not evident in this setting. Compelling evidence exists for unique cascades of biophysical, adhesive, stimulatory, and guidance factors that arrest neutrophils in the alveolar capillary bed and direct their movement through the endothelium, interstitial space, and alveolar epithelium. A prominent path accessible to the neutrophil appears to be determined by the structural interactions of endothelial cells, interstitial fibroblasts, as well as type I and type II alveolar epithelial cells.

Glycosaminoglycans in porcine lung: an ultrastructural study using cupromeronic blue

Glycosaminoglycans (GAGs) are essential components of the extracellular matrix contributing to the mechanical properties of connective tissues as well as to cell recognition and growth regulation. The ultrastructural localization of GAGs in porcine lung was studied by means of the dye Cupromeronic Blue in the presence of 0.3 M MgCl2 according to Scott's critical electrolyte concentration technique. GAGs were observed in locations described as follows. Pleura: Dermatan sulphate (DS) and chondroitin sulphate (CS) attached in the region of the d-band of collagen fibrils, interconnecting the fibrils; heparan sulphate (HS) at the surface of elastic fibers and in the basement membrane of the mesothelium and blood vessels. Bronchial cartilage: Abundant amounts of GAGs were observed in three zones: pericellular, in the intercellular matrix and at the perichondrial collagen. By enzyme digestion a superficial cartilage layer with predominantly CS could be distinguished from a deep zone with CS and keratan sulphate. The structure of the large aggregating cartilage proteoglycan was confirmed in situ. Airway epithelium: HS at the whole surface of cilia and microvilli and in the basement membrane of the epithelial cells. Alveolar wall: CS/DS at collagen fibrils, HS at the surface of elastic fibers and in the basement membranes of epithelium and endothelium.

Absence of binding and impermeability to ferritins of gill endothelium in marine teleosts

The surface binding characteristics and permeability properties of the endothelium of secondary lamellae from the gills of several species of marine teleosts were investigated by introducing cationized ferritin and native ferritin into the microcirculation under normal environmental conditions. Neither type of ferritin bound to the luminal surface of the gill endothelium. No transcellular movement of cationized ferritin was detected, either via transendothelial channels or individual vesicles, nor was passage of cationized ferritin through the tight intercellular junctions of the endothelium observed. Anionic binding sites in the endothelial basement membranes could not be identified. Binding and transport of ferritin were unaffected by normal changes in environmental temperatures over the range of -2 to + 15°C. These findings suggest that the endothelial cell surface of the gills from these fishes is a primary barrier to the extracapillary movement of blood borne constituents.

Characterization of proteoglycans synthesized by fetal rat lung type II pneumonocytes in vitro and the effects of cortisol

The synthesis of proteoglycans by primary cultures of 19-day gestation fetal rat lung Type II pneumonocytes was studied. The cells were grown in the presence of [3H]-glucosamine and/or [35S]-Na2SO4 and the radioactive label incorporated into proteoglycans was analyzed. Proteoglycans of high molecular weight (approximately 200 Kd) were isolated by gel permeation chromatography and contained both [3H] and [35S]. The glycosaminoglycan composition of the proteoglycans was determined by electrophoresis and autoradiography. The medium contained 65-80% of the labeled proteoglycans and was enriched for hyaluronate, with lesser amounts of the sulfated glycosaminoglycans (dermatan sulfate greater than heparan sulfate greater than chondroitin sulfate). The cell layers retained 20-35% of the labeled proteoglycans and was enriched for heparan sulfate, with lesser amounts of chondroitan sulfate greater than dermatan sulfate greater than hyaluronate. The synthesis of proteoglycans was time-dependent and was stimulated by increasing concentrations of fetal bovine serum. Cortisol inhibited proteoglycan synthesis, apparently by decreasing the availability of proteoglycan core-protein.

Partial chemical characterization of the anionic sites in the basal lamina of fenestrated capillaries

The distribution of anionic sites in the basal laminae of the blood capillaries of the murine pancreas was studied in specimens fixed in ruthenium red (RR)-glutaraldehyde mixtures. The sites appeared as discrete, small (6 to 18 nm) particles distributed throughout the three laminae but concentrated primarily in the lamina rara externa, in which--spaced 80-100 nm apart--they formed a planar, partially ordered lattice comparable to that revealed by cationized ferritin in previous studies (M. Simionescu, N. Simionescu, and G. E. Palade, 1982, J. Cell Biol. 95, 425-434). The chemical nature of the anionic sites was explored by incubating fresh tissue specimens in solutions of selected enzymes before fixation in RR-glutaraldehyde mixtures. Pronase P and papain removed completely the anionic sites and left behind an extensively degraded and disorganized basal lamina. Trypsin caused the removal of anionic sites only, did not degrade the rest of the basal lamina, but detached it completely from the endothelium. Chondroitinase ABC reduced slightly the size and the surface density of RR-stainable particles, and detached focally the rest of the basal lamina from the endothelium and pericytes. Crude heparinase caused a nearly complete removal of anionic sites, and pure heparitinase gave comparable but less extensive results. Similar effects were recorded on the basal laminae of smooth muscle fibers and pancreatic acini and ducts. The results indicate that the anionic sites of all basal laminae examined are contributed primarily by heparin sulfate proteoglycans and trace amounts of chondroitin sulfate proteoglycans.

Ultrastructure of opossum oocyte investing coats and their sensitivity to trypsin and hyaluronidase

Ovulated opossum oocytes are surrounded by a zona pellucida, but not by cumulus cells. Opossum sperm carry at least four acrosomal hydrolases (hyaluronidase, acrosin, N-acetylhexosaminidase, and arylsulfatase); the functions of these enzymes in opossum fertilization are uncertain. To identify possible substrates for these hydrolases, the ultrastructure of opossum oocytes was examined after fixation in the presence of ruthenium red which stabilizes extracellular matrices. This oocyte is unusual in having a wide perivitelline space containing a highly structured extracellular matrix (ECM). The ECM is comprised of granules and filaments, and it resembles matrices known to contain hyaluronic acid in other systems. Hydrolases, known to be present in opossum acrosomes, were tested for their effect on the ultrastructure of the zona pellucida and matrix of the perivitelline space. Trypsin dissolved the zona pellucida and decreased the size of the granules in the perivitelline space. Streptomyces hyaluronidase, which specifically attacks hyaluronic acid, removed only matrix filaments. Arylsulfatase, N-acetylhexosaminidase, and beta-glucuronidase did not affect the zona pellucida or ECM in our assay. These observations are consistent with the ideas that (1) opossum sperm must penetrate two oocyte investments, the zona pellucida and ECM of the perivitelline space; (2) the ECM contains hyaluronic acid (filaments) and protein (granules); (3) opossum sperm acrosin may function in penetration of the zona pellucida and ECM; and (4) opossum sperm hyaluronidase may function in penetration of the ECM by degrading hyaluronic acid (filaments). Dissolution of the granules and filaments from oocyte microvilli is probably necessary to permit close apposition and fusion of the sperm and oocyte membranes. The evolutionary significance of these results is discussed.

Hyaluronidase dissolves a component in the hamster zona pellucida

Mammalian sperm must pass between cumulus cells and corona radiata cells before reaching the surface of the zona pellucida which surrounds the oocyte. The cumulus and corona radiata cells are separated from each other by an extracellular matrix (ECM) containing hyaluronic acid. The structure of this ECM and of the zona pellucida was investigated in the hamster oocyte-cumulus complex (OCC) using transmission electron microscopy (TEM) following processing in ruthenium red. When fixed in the presence of ruthenium red, the ECM of the OCC and the zona pellucida were well preserved and highly structured. The ECM between corona radiata cells was comprised of a network of granules and filaments which resembled hyaluronic acid containing matrices described in other systems. The outer one-third to one-half of the zona pellucida was porous; the ECM of the corona radiata extended into these pores. Bovine testicular hyaluronidase, Streptomyces hyaluronidase, and hamster sperm extracts containing hyaluronidase each dispersed the cumulus cells and most of the corona radiata cells. TEM examination revealed that brief (5-10 min) hyaluronidase treatment of OCCs removed the matrix filaments and caused clumping of the granules in both the corona radiata and zona pellucida. Longer hyaluronidase treatments (15-30 min) removed both filaments and granules. Our observations are consistent with the ideas that: 1) the ECM between corona radiata cells contains hyaluronic acid, and 2) hyaluronic acid is present in the outer one-third to one-half of the zona pellucida.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteoglycan association with collagen d band in hyaline articular cartilage

Proteoglycans of canine articular cartilage were labelled for transmission electron microscopy using the cationic copper phthalocyanin dye, cupromeronic blue, in a critical electrolyte concentration method. Much of the proteoglycan appeared to be structurally unrelated to collagen but a small proportion was positioned close to fibrils. On demonstrating the characteristic collagen banding pattern with uranyl acetate and phosphotungstic acid, it was evident that proteoglycan interacted with collagen at the d band.

Ultrastructural distribution of sulfated complex carbohydrates in elastic cartilage of the young rabbit

Sulfated glycosaminoglycans are an integral component of elastic cartilage. We have investigated the ultrastructural distribution of sulfated complex carbohydrates (CC) in the mature cartilage and the perichondrium of young rabbit auricles using the high iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP) and the tannic acid-ferric chloride (TA-Fe) methods. In the mature cartilage, HID-TCH-SP stained intracellular Golgi saccules of the mature face, secretory granules, and the extracellular matrix granules, but staining was not discernible in collagen fibrils and osmiophilic elastic fibers consisting of only amorphous elastin. The HID and TA-Fe staining were similarly observed in matrix granules, whereas the elastic fibers and collagen fibrils lacked the staining. The pericellular matrix granules had a diameter of 34 +/- 5 nm (mean +/- SD; n = 30). Thiéry's periodate-TCH-SP (PA-TCH-SP) method stained vicinal glycol-containing CC in collagen fibrils but failed to stain matrix granules and elastic fibers. In the perichondrium, HID-TCH-SP staining of the organelles was less intense in the flattened chondrocytes when compared with those in large mature chondrocytes. The extracellular HID and HID-TCH-SP staining were observed in the matrix granules. The diameter of pericellular matrix granules (19 +/- 4 nm, mean +/- SD; n = 30) was significantly smaller when compared to those in the mature cartilage (P less than 0.001). The HID-TCH-SP staining was closely associated with collagen fibrils. However, the staining was not seen in collagen fibrils and osmiophilic elastic fibers consisting of elastin and microfibrils. The PA-TCH-SP method stained collagen fibrils and microfibrils but did not stain the amorphous elastin. Thus these studies demonstrate that sulfated CC are packaged in chondrocyte secretory granules and are released into the extracellular matrix to form matrix granules, but are not incorporated into collagen fibrils and elastic fibers.