The chemical and histochemical properties of alcian blue. IV. Further studies on the methods for the identification of acid glycosaminoglycans

Histochemistry and Cell Biology-a glance into the past and a look ahead

At the occasion of the 65th anniversary of Histochemistry and Cell Biology, we browse through its first ten years of publication and highlight a selection of papers from the early days of enzyme, protein, and carbohydrate histochemistry. In addition, we narrate recent progress to identify, quantify, and precisely determine the tissue localization of proteins and lipids, and small molecules by the combination of spectroscopic techniques and histology.

AEG-1 deletion promotes cartilage repair and modulates bone remodeling-related cytokines via TLR4/MyD88/NF-κB inhibition in ovariectomized rats with osteoporosis

Background

Osteoporosis is a systemic skeletal disorder that can impact a variety of bones throughout the body. Astrocyte-elevated gene-1 (AEG-1) is involved in multiple pro-tumorigenic functions and participates in various inflammatory reactions. However, whether it has an impact on osteoporosis-related cartilage repair and bone remodeling remains unknown.

Methods

We utilized an ovariectomy mouse model with AEG-1 deletion to investigate the role of AEG-1 in osteoporosis. The mRNA level of AEG-1 was detected by RT-PCR, bone markers, bone volume/total volume (BV/TV), trabecular bone surface/bone volume (BSA/BV) and trabecular bone thickness (Tb. Th) were detected by micro computed tomography (µCT), bone injury was observed by HE and alcian blue staining. The contents of IL-6, IL-17, iNOS and IL-10 in peripheral blood of the three groups were detected by ELISA. The expression of OSX, coi1a1, OC, TLR4, MyD88 and NF-κB were detected by Western Blot.

Results

µCT revealed increased bone volume in the AEG-1 knockout (KO) ovariectomy (OVX) group compared to the wildtype (WT) OVX group 4 weeks after surgery, indicating restored bone formation after AEG-1 deletion. Flow sorting revealed that AEG-1 deletion inhibited the production of inflammatory factors. Western blot demonstrated activation of the TLR4/MyD88/NF-κB pathway after LPS exposure, which was reduced by AEG-1 deletion. AEG-1 deletion also improved lipopolysaccharide (LPS) induced adverse reactions.

Conclusions

Taken together, these findings indicate that AEG-1 deletion improves cartilage repair and bone remodeling during osteoporosis, which may partly occur through the inhibition of the TLR4/MyD88/NF-κB signaling pathway.

A Draft Map of the Human Ovarian Proteome for Tissue Engineering and Clinical Applications

Fertility preservation research in women today is increasingly taking advantage of bioengineering techniques to develop new biomimetic materials and solutions to safeguard ovarian cell function and microenvironment in vitro, and in vivo,. However, available data on the human ovary are limited and fundamental differences between animal models and humans are hampering researchers in their quest for more extensive knowledge of human ovarian physiology and key reproductive proteins that need to be preserved. We therefore turned to multi-dimensional label-free mass spectrometry to analyze human ovarian cortex, as it is a high-throughput and conclusive technique providing information on the proteomic composition of complex tissues like the ovary. In-depth proteomic profiling through two-dimensional liquid chromatography-mass spectrometry, Western blotting, histological and immunohistochemical analyses, and data mining helped us to confidently identify 1508 proteins. Moreover, our method allowed us to chart the most complete representation so far of the ovarian matrisome, defined as the ensemble of extracellular matrix proteins and associated factors, including more than 80 proteins. In conclusion, this study will provide a better understanding of ovarian proteomics, with a detailed characterization of the ovarian follicle microenvironment, in order to enable bioengineers to create biomimetic scaffolds for transplantation and three-dimensional in vitro, culture. By publishing our proteomic data, we also hope to contribute to accelerating biomedical research into ovarian health and disease in general.

Histological changes of semitendinosus autograft after anterior cruciate ligament reconstruction in an immature rabbit model

Introduction

The anterior cruciate ligament (ACL) injury is one of the most common in the knee. Tendons can be used as alternative grafts for ACL repair, with tendon “ligamentization” often reported in literature. The purpose of this study was to evaluate the morphological and histological changes occurring in a semitendinosus tendon (ST) during ACL reconstruction in growing rabbits.

Materials and methods

Twenty-one 8-week-old New Zealand white rabbits, weighing about 1500 g underwent reconstructive surgery on the right knee. In two cases the left knee was used to verify the normal microstructure of the ACL and ST in rabbits. The rabbits were then randomly divided into seven groups and sacrificed at 1, 4, 6, 8, 12, 24 and 48 weeks after surgery. The specimens were evaluated under light microscopy to analyze the changes in the intra-articular tract of the graft. The evidence of necrosis, neovascularization and organization of the collagen fibers were investigated.

Results

One month after surgery, numerous disorganized fibroblasts and collagenous fibers were identified. A marked reduction of cellular necrosis was observed in the early phase of the neo-ligament healing process. After 4 weeks, these fusiform-like cells became more rounded. By 8 weeks, the collagen fibers had become aligned in parallel with newly formed capillaries and highly differentiated fibroblasts. At 24 and 48 weeks the transplanted tendon differed histologically from both tendon and ligament.

Conclusions

The data of the present study showed that ligamentization did not occur until at least 24 months post-operatively and, during healing, the grafted tendon assumed a unique micro-architecture that was a middle between a tendon and a ligament.

The ACL reconstruction in pediatric age has become more frequent in these past recent years. The use of semitendinosus graft with preservation of its distal attachment should be the gold standard in skeletally immature patients.

Morphological and histochemical observations on the digestive system of Cotylophoron cotylophorum

The amphistome Cotylophoron cotylophorum feeds entirely on semidigested rumenal contents (plant material living bacteria, and protozoa). Morphological and histochemical studies have been made of the digestive system. Two types of cells occur in the caecal epithelium, the first type were larger and cuboidal with granular cytoplasm containing a high amount of RNA and proteins. The second smaller type were fewer, and contained pyknotic nuclei; their cytoplasm was vacuolated. The cells of the first type bear microvilli at the luminal surface. The surface coat consists of saliva resistant acetylated acid mucopolysaccharides containing hyaluronic acid with carboxyl polyanions. Intense activities of acid phosphatase, glucose-6-phosphatase, and ATPase, and moderate activities of nonspecific esterase and lipase are localized at the brush border. The functional significance of the surface carbohydrates and the hydrolytic enzymes has been discussed in relation to digestion and absorption of nutrients.

Histochemical studies of the extracellular matrix of human articular cartilage--a review

OBJECTIVE

This paper reviews the histochemistry of the extracellular matrix of human articular cartilage. No systematic review of histochemical knowledge and techniques in the study of articular cartilage has been published previously.

METHODS AND RESULTS

Literature was searched in the Winspirs Medline database from 1960 to 2000. Only techniques applicable for bright field or polarization microscopy were considered. Unless otherwise noted, all applies to hyaline cartilage. The most widely used fixatives are adequate for routine staining of proteins, but proteoglycan fixation is problematic, and no one fixative can be recommended. Proteoglycan can be stained reliably but it is problematic that, at low substrate concentrations, these methods are not stoichiometric. Collagen can be stained efficiently, although attempts to differentiate collagen types have not been successful.

CONCLUSIONS

Detailed studies of fixation and staining procedures should be carried out and standards for cartilage sampling, handling and evaluation agreed upon if results from different laboratories are to be compared.

Microscopic and histochemical manifestations of hyaline cartilage dynamics

Structure and function of hyaline cartilages has been the focus of many correlative studies for over a hundred years. Much of what is known regarding dynamics and function of cartilage constituents has been derived or inferred from biochemical and electron microscopic investigations. Here we show that in conjunction with ultrastructural, and high-magnification transmission light and polarization microscopy, the well-developed histochemical methods are indispensable for the analysis of cartilage dynamics. Microscopically demonstrable aspects of cartilage dynamics include, but are not limited to, formation of the intracellular liquid crystals, phase transitions of the extracellular matrix and tubular connections between chondrocytes. The role of the interchondrocytic liquid crystals is considered in terms of the tensegrity hypothesis and non-apoptotic cell death. Phase transitions of the extracellular matrix are discussed in terms of self-alignment of chondrons, matrix guidance pathways and cartilage growth in the absence of mitosis. The possible role of nonenzymatic glycation reactions in cartilage dynamics is also reviewed.

Ultrastructure of adult human articular cartilage matrix after cryotechnical processing

The ultrastructure of adult human articular cartilage matrix is reexamined in tissue processed according to recently improved cryotechniques [Studer et al. (1995) J. Microsc., 179:321-332]. In truely vitrified tissue, a network of fine cross-banded filaments (10-15 nm in diameter) with a periodicity characteristic of collagen fibrils is seen throughout the extracellular substance, even within the pericellular compartment, which has hitherto been deemed free of such components. Proteoglycans fill the interstices between these entities as a homogeneously distributed granular mass; they do not manifest a morphologically identifiable reticular structure. Longitudinally sectioned collagen fibrils exhibit variations in thickness and kinking; they tend to align with their periodic banding in register and are frequently seen to split or fuse along their longitudinal course. The tendency of fibrils to form bundles is greater in deeper zones than in more superficial ones. A duality in the orientation of fibrils and fibril bundles is observed within the interterritorial matrix compartment: superimposed upon the well-characterized arcade-like structure formed by one subpopulation is another, more randomly arranged one. The classical concepts of matrix organization thus need to be modified and refined to encompass these findings.

Histochemical analysis of newly synthesized and accumulated sulfated glycosaminoglycans during musculogenesis in the embryonic chick leg

The leg musculature from 11, 14, and 17 day chick embryos was analyzed histochemically to investigate the temporal and spatial distribution of various types of sulfated glycosaminoglycans present during skeletal muscle development. Types of glycans were identified by selective degradation with specific glycosidases and nitrous acid coupled with Alcian blue staining procedures for sulfated polyanions and with [35S]sulfate autoradiography. On day 11, radiolabeled chondroitin sulfate glycosaminoglycans are localized extracellularly in both the myogenic and connective tissue cell populations. By day 17, incorporation of [35S]sulfate into chondroitin sulfate is substantially reduced, although Alcian blue-stained chondroitin sulfate molecules are still detectable. With increasing age and developmental state of the tissues, radiolabeled and stained dermatan sulfate and heparan sulfate progressively increase in relative quantity compared to chondroitin sulfate both in muscle and in associated connective tissue elements. These changes in glycosaminoglycans correlate well with similar changes previously determined biochemically and further document the alterations in extracellular matrix components during embryonic skeletal myogenesis.

Histochemical studies of the colonic epithelial glycoproteins of the normal rabbit

Two general classes of glycoproteins have been identified in the colonic epithelial cells of New Zealand white rabbits. Each is associated with an ultrastructurally distinct secretory cell. The first of these classes is found in cells, termed vesiculated columnar cells, characterized by electron-translucent vesicles, a small rough endoplasmic reticulum-Golgi complex and prominent microvilli. The glycoproteins of the vesiculated cells contain abundant O-sulphate ester, sialic acids with ester substituents at positions C-8 or C-9 (or with two or three side chain substituents) and neutral sugars with vicinal diols whose periodate oxidation is prevented by an O-acyl ester substituent(s). The second class of glycoproteins occurs in goblet cells characterized by electron-dense vesicles, an abundant rough endoplasmic reticulum, a well-developed Golgi apparatus and few, if any, microvilli. Goblet cells along the entire length of the crypts contain neutral sugars with periodate-oxidisable vicinal diols and a ferriferricyanide-reactive component. Cells in the upper halves of the crypts also contain components that are sulphated, Schiff-reactive and acid-fast. In the lower halves of the crypts, the goblet cells contain smaller quantities of the above components plus sialic acids, some of which possibly have an O-acyl substituent located at position C-8 or C-9 (or which have two or three side chain O-acyl substituents). It is suggested that the function of the glycoproteins from the vesiculated columnar cells is protective and that from the goblet cells is lubricative.

Fine-granular cationic iron colloid. Its preparation, physicochemical characteristics and histochemical use for the detection of ionized anionic groups

In order to obtain distinct and reliable information concerning the localization of ionized anionic groups in tissues, fine-granular cationic ferric hydroxide colloid solution (Fe-Cac-f) was newly devised. This can be obtained by boiling a mixture of ferric chloride and ammonium cacodylate solutions. The colloid particles of Fe-Cac-f are about 1.0 nm in size, i.e., one-fifth of the size of ferric cacodylate colloid (Fe-Cac; Seno et al. 1983a). As with Fe-Cac, Fe-Cac-f particles in the pH range of 1.6-7.6 carry a positive electric charge, but the latter show a better permeation of tissues. Using the Prussian blue reaction, Fe-Cac-f gives a distinct deep-blue color and can be used for the detection of anionic groups of acid mucopolysaccharides and proteins by light microscopy. It is also useful for detecting the exact sites of ionized anionic groups in deep tissue areas using electron microscopy.

Glycosaminoglycans in the basal lamina and extracellular matrix of serially aged mouse mammary ducts

The synthesis and accumulation of specific glycosaminoglycans into proteoglycans of the basal lamina and extracellular matrix is an important aspect of ductal growth and branching morphogenesis in the mouse mammary gland. The present study was undertaken to determine whether serially aged mammary gland, which has lost most of its growth potential during repeated transplantation, displays altered ability to synthesize and accumulate glycosaminoglycans into the extracellular matrix or basal lamina. Using histochemical and autoradiographic procedures coupled with enzymatic digestion, it is now shown that serially aged mammary ductal tissue synthesizes and incorporates hyaluronate into the basal lamina at the leading edge of the end bud, where growth takes place, and sulfated glycosaminoglycans are accumulated in the extracellular matrix along the end bud flanks, associated with ductal morphogenesis. These patterns of synthesis and accumulation are similar to those associated with the growth of young gland. In non-growing regions, regardless of whether growth termination resulted from serial aging or from normal growth regulatory mechanisms operating in the young gland, sulfated glycosaminoglycans were distributed in the extracellular matrix around the ductal tips. Again, the pattern was similar in young and serially aged gland. We conclude that glycosaminoglycan metabolism and distribution are related to growth status rather than tissue age, and are unlikely to be an important component of mammary senescence.

Ultrastructural cytochemistry of proteoglycans associated with calcification of shark cartilage

Proteoglycans (PGs) as well as sulfated glycosaminoglycans (GAGs) are closely associated with cartilage calcification. An inner zone of endoskeletal tesserae of sharks is composed of a unique calcified hyaline cartilage. Initial calcification can be seen in the cartilage close to the inner zone. We have ultrastructurally examined shark, Triakis scyllia, noncalcifying, calcifying, and calcified cartilage using the tannic acid-ferric chloride (TA-Fe), the high iron diamine (HID), and the HID-thiocarbohydrazide-silver proteinate (HID-TCH-SP) methods for localization of sulfated complex carbohydrates. In noncalcifying cartilage, TA-Fe and HID strongly stained matrix granules which were round, ovoid, elongated, or irregularly shaped and presumably represented PG monomers. The size and staining intensity of the reactive matrix granules progressively decreased in calcifying cartilage toward the calcification front of the calcified cartilage. Similarly, a progressive decrease in the size of the HID-TCH-SP stain deposits in the matrix granules was observed in the calcifying cartilage close to the calcification front and was interpreted as a decrease in length of sulfate containing GAG chains. In the calcified cartilage, the highly calcified areas were often localized in the calcification front and contained few or no small HID-TCH-SP stain deposits, whereas the weakly calcified regions contained more stain deposits. These results indicate that partial and complete degradation of sulfated GAGs and/or PGs may be a requisite for calcification of shark cartilage.

Bone formation by isolated calvarial osteoblasts in syngeneic and allogeneic transplants: light microscopic observations

Taking advantage of recently developed methods for osteoblast isolation, we used these cells to study bone morphogenesis in syngeneic and allogeneic intramuscular transplants. Syngeneic osteoblasts from fetal rat calvaria produced small islands of bone by the third day after transplantation. These islands increased in size and began to fuse after about 14 days. At the surface of the woven bone laid down first, lamellar bone developed. The amount of this bone increased, and in 56-day-old transplants solid blocks of bone were present. Osteoclasts were scarce, and the woven bone remained unresorbed. Bone marrow was absent. The structure of bone in transplants differed from that of mature calvarial bones in which only remnants of woven bone remained and bone marrow was well developed. The scarcity of osteoclasts in transplants could be caused by their relative paucity among the injected cells, since these cells responded strongly to added parathyroid hormone by increased production of cyclic adenosine monophosphate (cAMP) but only weakly to calcitonin. Osteoblasts isolated from the surface of calvarial lamellar bone of 28-day-old rats formed woven bone similar to the bone formed by fetal cells. This suggests that the type of bone produced does not depend on the intrinsic properties of the osteoblasts. Bone formed in an allogeneic system was surrounded by infiltrations containing lymphocytes, macrophages, and osteoclastlike cells in 14-day-old transplants. Osteoblasts at the bone periphery were destroyed and bone matrix was resorbed by infiltrating cells. Numerous bone lacunae were enlarged, suggesting the occurrence of osteocytic osteolysis. Isolated osteoblasts cultured for three population doublings or longer did not form bone after transplantation, although they retained some reactivity toward parathyroid hormone.

Staining of interphase nuclei and mitotic figures in cultured cells with alcian blue 8GX

Cultured endothelial cells derived from bovine calf pulmonary artery were subjected to a variety of fixatives and stained with 1% Alcian blue 8GX at pH 2.59 to 3.26. Within this range of pH, interphase nuclei and especially mitotic figures were (a) strongly stained in cells fixed with 10% formalin (phosphate buffered or unbuffered) or 2.5% buffered glutaraldehyde, (b) weakly stained or unstained in cells fixed in formaldehyde containing divalent cations, and (c) unstained in cells fixed in acetic acid-containing fluids. However, optimal nuclear staining with Alcian blue under the conditions of this study was judged to be achieved after fixation with neutral phosphate buffered 10% formalin. Endothelial cell cytoplasm exhibited a similar fixative-dependent staining. At pH 2.59 the cytoplasm of interphase cells fixed in formaldehyde (containing no divalent cations) or glutaraldehyde remained unstained; however, at higher pH cytoplasmic staining did occur and it increased as pH increased. In contrast, when these latter fixatives were employed the cytoplasm of mitotic cells stained at all pH levels tested. In cultured endothelial cells after appropriate fixation, 1% Alcian blue 8GX (pH 2.59) was found to possess the ability to stain nuclei with a selectivity and intensity that compared favorably to those of the Feulgen reaction of Heidenhain iron hematoxylin but without the latters' length and complexity. Therefore, this procedure may provide a rapid, simple, and selective method for visualizing interphase nuclei or mitotic figures, or both in the majority of cultured cells.

Staining of demineralized cartilage. I. Alcoholic versus aqueous demineralization at neutral and acidic pH

Demineralization of cartilage with alcoholic EDTA provides cartilage staining that is no better, as measured by scanning microdensitometry, than that of adequately fixed specimens demineralized with aqueous EDTA. Aqueous EDTA is a faster demineralizing agent than alcoholic EDTA. Certain fixatives can preserve maximal proteoglycan staining in articular cartilage even with subsequent rapid demineralization in formate buffer at pH 3.3. Although alcoholic formalin fixation provided optimum quantitative cartilage staining, cetylpyridinium chloride (CPC) in aqueous buffered formalin improved cellular detail, but CPC partially suppressed matrix staining.

Biochemical and structural abnormalities of the connective tissue in Larsen's syndrome

Skin, iliac crest cartilage and tendon of a patient affected with Larsen's syndrome were subjected to biochemical and ultrastructural investigation. A substantial increase in the ratio of glucosamine to galactosamine was found both in skin and cartilage. Ultrastructural abnormalities of collagen fibres and proteoglycan filaments were also found in Larsen's tissues. The significance of these findings are discussed.

[Studies of the mucopolysaccharid metabolism in the juvenile angiofibroma (author's transl)]

The mucopolysaccharide content of juvenile angiofibromas is investigated using histochemical and ultrahistochemical methods (histochemical in ten cases, ultrahistochemical in four cases). The investigations result in typical histochemical features and show the localization of acid mucopolysaccharides at electronmicroscopical level. The endothelium of the vessels exhibits a strong PAS-reaction and also shows acid groups at the cell surfaces. The interstitial tissue demonstrates neutral perjodatreactive substances as well as acid mucopolysaccharides. The latter substances mainly reacted in perifibrillar position. Electronmicroscopically the perjodreactive material was localized in the cytoplasma of typical fibroblasts and their modulations resembling histiocytes. The acid groups of carboxylated and sulfated mucopolysaccharides of the intercellular substance could be determined as hyaluronic acides and chondroitinsulfates (Chondroitin-4 and Chondroitin-6 sulfate) using the critical-electrolyte-concentration method after Scott and Dorling. Ultrastructurally these acid groups are localized as cell coat covering the fibroblasts and between the collagen fibrils. This histochemical investigation also supports the thesis of an organoid growth pattern of juvenile angiofibroma.

Osteogenesis imperfecta: morphological, histochemical and biochemical aspects. Modifications induced by (+)-catechin

Two patients affected with two different forms of Osteogenesis Imperfecta were examined in order to study collagen and glycosaminoglycans (GAGs) in skin and iliac crest cartilage. A sharp decrease of the galactosamine to glucosamine ratio due to a reduced content of chondroitin sulfate was evidenced in both patients. Moreover the structure of proteoglycans appeared altered, this being more evident in the severe form of the disease. Morphological examination in light and electron microscopy of cartilage of the less severely diseased patient showed that GAGs in the extracellular matrix did not present regular connection with collagen fibers. Chondrocytes, elongated and disorderly scattered, showed large lipidic inclusions and, on histochemical basis, were devoid of UDPG dehydrogenase activity. Treatment with (+)-catechin produced an improvement, in both patients, of the biochemical pattern of collagen and GAGs. Similarly a shift of the cellular activity and of the matrix morphology towards normality was observed in the investigated cartilage of the less severely affected patient.

Cytochemistry of colloidal iron binding to the surface of Hela cells and human erythrocytes

It seems from the literature that colloidal iron (C.I.) binding sites on cell surfaces cannot be completely removed by treatment with Vibrio Colerae alpha-neuraminidase. We wondered if C.I. particles bind to negative groups other than the carboxyl groups of sialic acids. Using HeLa cells from suspension cultures and fresh human erythrocytes, we examined, with the transmission electronmicroscope, the influence of the following enzymatic and histochemical treatments on C.I. staining: alpha-neuraminidase; hyaluronidase; ribonuclease; alpha-amylase; mild methylation (MM); MM + saponification (Sap.); MM + Sap +MM; MM + Sap + alpha-neuraminidase; active methylation (AM); AM + Sap; AM + Sap + AM; AM + Sap + alpha-neuraminiadase; CH3OH (80%); Sap. It seemed from these experiments that the carboxyl groups of alpha-neuraminidase sensitive sialic acids constitute the majority of binding sites for C.I. to these particular cells. The most interesting candidates for the residual binding of C.I. are carboxyl groups of alpha-neuraminidase resistant molecules, sulfon, sulfin, and sulfate groups.

Histochemical characterization of mucosubstances in bone and soft tissue-tumors

The present investigation endeavors to characterize the mucosubstance content of 170 myxoid and chondromatous tumors and chordomas by histochemical methods. The results obtained using the critical electrolyte concentration (CEC) method as introduced by Scott and co-workers23,24 were compared with those obtained by staining with alcian blue and toluidine blue at different pH's with and without pretreatment with bovine testicular hyaluronidase. Tissues known biochemically to contain different heteroglycans were used as controls: synovial fluid and cock's comb (hyaluronic acid) stained with alcian blue up to a MgCl2 concentration of 0.1 M; fetal cartilage (chondroitin 4- and 6-sulphate) pulposus with notochordal remnants (keratan sulphate) up 10 1.0 M. The staining reaction of intramuscular myxoma and myxoid liposarcoma corresponded to that of synovial fluid and cock's comb (containing hyaluronic acid). Benign chondromatous tumors (osteochondroma, enchondroma, extraskeletal chondroma, chondromatosis in bursae, synovia, and tendon) as well as well-differentiated chondrosarcomas had a similar staining reaction to that of adult cartilage (containing keratan sulphate). However, the intensity of the reaction was lower in these tumors than in the adult cartilage, indicating that the keratan sulphate content of the tumors is lower. Most of the moderately well-differentiated chondrosarcomas, the poorly differentiated chondrosarcomas, and pulmonary metastases of chondrosarcoma, as well as mesenchymal chondrosarcoma and extra-skeletal chondrosarcoma possessed the same staining properties as fetal cartilage, known to contain chondroitin 4- and 6-sulphate but not keratan sulphate. A few of the moderately well-differentiated chondrosarcomas stained up to a MgCl2 concentration of 1.0 M. Three cases of poorly differentiated chondrosarcomas stained with alcian blue up to 0.35-0.45 M in the lowest differentiated areas, indicating the presence of sulphated heteroglycans, as chondroitin 4- and 6-sulphate. Most chordomas possessed the same staining properties as fetal cartilage; however, a few chordomas stained in the same way as notochordal remnants of nucleus pulposus (containing keratan sulphate), which are thought to be the origin of these tumors. The results of staining of the tumors in the present series with the Scott technique corresponds well with toluidine blue and alcian blue at different pH's with and without pretreatment of the sections with testicular hyaluronidase. Since bone and soft tissue tumors may contain varying mucosubstances depending on the tissue of origin and on differentiation, histochemical investigation of the heteroglycan content of these tumors may be a valuable diagnostic aid.

Characterization of developing antler cartilage matrix. I. Selected histochemical and enzymatic assessment

Biopsy samples of the main beams and tines were obtained from the antlers of mature Rocky Mountain mule deer (Odocoileus hemionus hemionus) during the rapid phase of the antler grow-th cycle. The samples were studied using histochemical and enzymatic techniques for the demonstration of mucosubstances. The reserve mesenchyme contained chondroitin 4- and 6-sulfates, hyaluronic acid and sialic acid. During prechondroblastic and chondroblastic differentiation, some strongly sulfated mucopolysaccharides were complemented by low molecular weight or incompletely sulfated chondroitin 4- and 6-sulfates. During maturation of the cartilage strongly anionic mucopolysaccharides (possibly heparin, keratan and/or dermatan sulfates) were present in the general matrix and especially prominent along the capsular margins. Calcification foci, beginning initially in the mid-trabecular regions and eventually extending to the trabecular margins, were highly reactive for mucosubstances and were enzyme-resistant. This histochemical study establishes the cartilaginous nature of the developing deer antler, defines some of the mucosubstance constituents involved in the chondrogenic and calcification process, and confirms the utility of the antler as a model for chondrogenic and calcification studies.

Acid mucopolysaccharide (glycosaminoglycan) at the epithelial-mesenchymal interface of mouse embryo salivary glands

Acid mucopolysaccharide (glycosaminoglycan) has been demostrated at the epithelial-mesenchymal interface of mouse embryo submandibular glands by (a) specific staining for polymeric sulfate with Alcian blue 8 GX at various magnesium concentrations, (b) specific staining for polymeric uronic acid by selective oxidation of these residues to Schiff-reactive compounds, (c) electron microscope localization of ruthenium red staining, (d) radioautographic localization of glucosamine-(3)H and (35)SO(4), and (e) by susceptibility of the glucosamine radioactivity at the interface to digestion with protease-free hyaluronidase. Moreover, material labeled with glucosamine-(3)H and (35)SO(4) and with chemical characteristics identical with those of acid mucopolysaccharide were isolated from the glands. Acid mucopolysaccharide is distributed over the entire epithelial surface. The amount of acid mucopolysaccharide, as revealed by the staining procedures, is nearly equivalent at all sites. In contrast, the rate of accumulation of glucosamine-labeled mucopolysaccharide is greater at the surface of the distal ends of the growing and branching lobules. This distribution of newly synthesized acid mucopolysaccharide at the sites of incipient cleft formation suggests that surface-associated acid mucopolysaccharide is involved in the morphogenetic process. A mechanism of branching morphogenesis is proposed which accounts for the distribution of collagen fibers and total and newly synthesized acid mucopolysaccharide at the epithelial surface.