Changes in glycoconjugates revealed by lectin staining in the developing airways of Syrian golden hamsters

Lectin binding was studied in the developing airways of Syrian golden hamsters on gestational days 11–16 (day 16 is the day of birth). The trachea and lungs were fixed in 4% formaldehyde-1% glutaraldehyde, 6% mercuric chloride-1% sodium acetate-0.1% glutaraldehyde, and 95% ethanol; embedded in paraffin; and stained with eight lectin-horseradish peroxidase conjugates: Triticum vulgare (WGA), Dolichos biflorus (DBA), Helix pomatia (HPA), Maclura pomifera (MPA), Griffonia simplicifolia I-B4 (GSA I-B4), Arachis hypogaea (PNA), Ulex europeus I (UEA I), and Limulus polyphemus (LPA). Each lectin yielded a characteristic staining pattern, which modulated throughout development. In general, changes in staining characteristics of the tracheal epithelium preceded similar changes in the lobar bronchus, bronchiole, and alveolus. In the case of UEA I, MPA, WGA, and HPA, staining increased with time uniformly over the luminal surface of all epithelial cells. However, in the case of PNA, GSA I-B4, and LPA, after the differentiation of ciliated and secretory cells, the apical surfaces of the ciliated cells stained more intensely than the apical surfaces of the secretory cells. Neuraminidase pretreatment enhanced PNA and GSA I-B4 staining in both cell types. In the case of PNA, these light microscopic observations were confirmed by ultrastructural study. Unlike the other lectins, the pattern of staining with DBA was unusual. Staining was moderate at first, then decreased (days 13 and 14), then increased at all airway levels. This study shows that different glycoconjugates modulate in airway epithelial cells throughout fetal development.     

Changes in glycoconjugates revealed by lectin staining in the developing airways of Syrian golden hamsters.

Lectin binding was studied in the developing airways of Syrian golden hamsters on gestational days 11-16 (day 16 is the day of birth). The trachea and lungs were fixed in 4% formaldehyde-1% glutaraldehyde, 6% mercuric chloride-1% sodium acetate-0.1% glutaraldehyde, and 95% ethanol; embedded in paraffin; and stained with eight lectin-horseradish peroxidase conjugates: Triticum vulgare (WGA), Dolichos biflorus (DBA), Helix pomatia (HPA), Maclura pomifera (MPA), Griffonia simplicifolia I-B4 (GSA I-B4), Arachis hypogaea (PNA), Ulex europeus I (UEA I), and Limulus polyphemus (LPA). Each lectin yielded a characteristic staining pattern, which modulated throughout development. In general, changes in staining characteristics of the tracheal epithelium preceded similar changes in the lobar bronchus, bronchiole, and alveolus. In the case of UEA I, MPA, WGA, and HPA, staining increased with time uniformly over the luminal surface of all epithelial cells. However, in the case of PNA, GSA I-B4, and LPA, after the differentiation of ciliated and secretory cells, the apical surfaces of the ciliated cells stained more intensely than the apical surfaces of the secretory cells. Neuraminidase pretreatment enhanced PNA and GSA I-B4 staining in both cell types. In the case of PNA, these light microscopic observations were confirmed by ultrastructural study. Unlike the other lectins, the pattern of staining with DBA was unusual. Staining was moderate at first, then decreased (days 13 and 14), then increased at all airway levels. This study shows that different glycoconjugates modulate in airway epithelial cells throughout fetal development.     

Lectin binding to serous ovarian tumours.

Sections of normal ovarian surface epithelium, benign serous cystadenomas, borderline serous cystadenomas and serous cyst-adenocarcinomas were stained with a pattern of lectins (Con A, WGA, SBA, DBA, UEA I, PNA and RCA I) to determine the different glycoproteins and their cellular changes. The epithelial cells stained with Con A, WGA, UEA I and RCA, although the intensity of the staining was generally higher in the malignant tumours. PNA stained only the malignant cells of the cystadenocarcinoma and DBA only the benign epithelial cells. These findings show that ovarian epithelial cells contain different glycoconjugates and that malignant transformation is accompanied by changes in the composition of these glycoconjugates.     

Lectin-binding affinities of the epithelium in the respiratory tract. A light microscopical study of ciliated epithelium in rat, guinea pig, and hamster

Complex carbohydrate components of surface coat and secretory granules were investigated in the laryngo-tracheo-bronchial epithelium of 3 laboratory animals (rat, guinea pig, and Syrian hamster). 2 groups of epithelial cells were distinguished in the light microscope: ciliated cells and non-ciliated cells. The latter mainly represent secretory cells and are subdivided into serous and mucous secretory cells. Apical glycocalix: In the rat, ciliated cells possess a significant number of Con A, RCA I, and WGA receptors, and a smaller number of UEA I binding sites. In hamsters and in guinea pigs additional binding sites for HPA could be demonstrated. The apical glycocalix of the non-ciliated cells in the rat evince marked staining with RCA I, WGA, and HPA, and less intensive binding of UEA I. In guinea pigs and in hamsters, the presence of additional Con A receptors was noted. Basolateral glycocalix: The basolateral surface coat of ciliated and non-ciliated cells shows identical lectin binding affinities. In the rat, the basolateral glycocalix binds RCA I; in the guinea pig, in addition, positive staining with UEA I and HPA is observed; in the hamster, the basolateral surface coat is outlined by RCA I and HPA receptors. Secretory products: Secretory granules of mucous cells in the rat react with Con A, UEA I and HPA lectins. In guinea pigs, these substances also bind RCA I and WGA lectins. Mucous granules in the secretory cells of the hamster are positive for Con A, RCA I, and HPA lectins. Granules of non-ciliated serous cells of rats bind Con A, UEA I, and HPA lectins. In the guinea pig, this reaction is weaker for UEA I lectin but comparable for Con A and HPA binding. A positive reaction with RCA I lectin only is found in the serous secretory granules of the hamster.     

Lectin histochemistry on the dorsal epidermis of the Breton dog

Expression of sugar residues and the nature of oligosaccharide linkage during keratinocyte maturation in the epidermis of the Breton dog were studied with the use of lectin histochemistry. Thirteen lectins were used. Labelling was not observed with GSA I-B4, GSA II, UEA-I, and LTA. The cytoplasm of keratinocytes reacted with PNA, HPA, Con A, and WGA from the basal layer to the granular layer. PNA and Con A showed highest reactivity in the granular cell layer. The cell surface showed increased reactivity with PNA, HPA, and WGA with maturation of keratinocytes. KOH-neuraminidase treatment (KOH-Neu) increased PNA and RCA120 staining during keratinocyte differentiation thus indicating an increase in oligosaccharides terminating with sialic acid-Galbeta(1,3)GalNAc and sialic acid-Galbeta(1,4)GlcNAc, respectively. Labelling of the glycocalyx of basal and spinous keratinocytes with SNA and MAA revealed terminal Neu5acalpha(2,6)Gal/GalNAc and Neu5acalpha(2,3)Galbeta(1,4)GlcNAc. KOH-Neu-DBA showed oligosaccharides terminating with sialic acid-GalNAcalpha(1,3)GalNAc in the spinous and granular layers. A selective glycocalyx labelling of granular keratinocytes was observed with DBA and SBA. Reactions with MAA, PNA, DBA, RCA120, SBA, HPA, and WGA disappeared after the beta-elimination reaction. Our findings indicate that Breton dog epidermis contains more O-linked than N-linked oligosaccharides and confirm that different subpopulations of keratinocytes can be distinguished by lectin histochemistry.     

Lectin binding to the human retina

Formalin-fixed, paraffin-embedded tissue sections of the human retina were stained with different fluorescein isothiocyanate-conjugated lectins. The lectins used were concanavalin A (Con A), Triticum vulgaris (WGA), glycine maximum (SBA), Dolichos biflorus (DBA), Ulex europaeus (UEA I), Arachis hypogaea (PNA), and Ricinus communis (RCA I). Con A stained both the inner and outer segments of the rods and cones, whereas WGA stained the inner and outer segments of the rods and the outer segments of the cones. PNA selectively stained only the inner segments of the cones. In addition, Con A and WGA stained neuron cytoplasm and nerve fibers in different layers of the retina. The results obtained differ in some important aspects from those previously obtained in the frog and monkey retina; this finding may be due to species differences. The results of lectin staining in the normal human retina may form the basis for future studies of retinal diseases.     

Lectin binding sites in developing mouse limb buds

Summary The binding sites of the following biotinylated lectins were demonstrated in serial paraffin sections of fore- and hindlimb buds from day-9 to day-16 mouse embryos with the Avidin-Biotin-Peroxidase Complex (ABC) procedure: Concanavalin A (Con A), Soybean Agglutinin (SBA), Wheat Germ Agglutinin (WGA), Peanut Agglutinin (PNA), Ricinus Communis Agglutinin I (RCA), Ulex Europaeus I Agglutinin (UEA), and Dolichos Biflorus Agglutinin (DBA). Alternating neighbouring sections were used to compare the distribution of PNA staining, PNA staining after neuraminidase treatment (N-PNA) and the autoradiographic sites of [³⁵S]-sulphate uptake. Unspecific binding sites common to all lectins tested were observed in periderm and chondrocytes. Several lectin affinities were seen in the undifferentiated mesoderm (Con A, WGA, RCA), blood vessels (WGA, PNA, N-PNA, RCA, UEA, DBA) and macrophages (Con A, WGA, N-PNA, RCA). A very selective and mainly extracellular affinity to N-PNA was demonstrated in the condensed preskeletal mesoderm, where it characterizes indistinct prospective chondrogenic, perichondral and pre-articular areas. Comparison with the distribution pattern of [³⁵S]-sulphate uptake and other previously published histochemical data suggests that N-PNA staining occurs at the late blastema stage, i.e. after the stage of cell condensation and before the earliest deposit of stainable matrix in chondrogenic areas. This property later disappears from the chondrifying rudiments, and is maintained in perichondral and pre-articular tissues. Surprisingly, only the pre-articular areas bind PNA without pretreatment with neuraminidase. A transient RCA binding probably related to terminal morphogenesis was detected in the undifferentiated distal part of the predigital columns of day-12 and day-13 limb buds. From the day-13 stage onwards, diverse new lectin affinities appeared in differentiating tissues, such as pretendinous rudiments, perichondrium and prospective periosteum, muscular connective tissue, myotubes, superficial fasciae and prospective dermis. A strong SBA and PNA staining was also detected in the extracellular matrix associated with the epithelial septa separating the roots of the digits in day-15 and day-16 limb buds.     

Changes in glycoconjugates revealed by lectin staining and stage-specific embryonic antigen-1 immunostaining in hamster submandibular glands during the postnatal period

Lectin binding and stage-specific embryonic antigen-1 (SSEA-1) immunoreactivity were studied in the developing submandibular glands of young Syrian golden hamsters (Mesocricetus auratus) from postnatal day 1 (the day of birth) to day 28. The submandibular glands were fixed in a solution containing 6% mercuric chloride, 1% sodium acetate, and 0.1% glutaraldehyde (HgCl₂-G) or 4% paraformaldehyde (4P), and embedded in paraffin. Sections from HgCl₂-G fixation were stained with three lectin-peroxidase conjugates: peanut agglutinin (PNA), Ulex europeus I agglutinin (UEA I), and wheat germ agglutinin (WGA). Sections from the 4P-fixed tissues were immunostained with monoclonal antibodies against SSEA-1, sialyl SSEA-1 and fucosyl SSEA-1. On the day of birth, the terminal unit of the submandibular gland was composed of fetal type secretory cells and proacinar cells. The secretory cells were PNA, UEA I, and WGA positive. The number of secretory terminal tubule cells decreased rapidly, and lectin-positive secretory cells were replaced by adult secretory cells that did not show PNA or UEA I stainings but were weakly positive for WGA. Fetal secretory cells were positively immunostained for SSEA-1 and sialyl SSEA-1, and immature ductal cells were stained for fucosyl SSEA-1. The positive stainings disappeared with regression of the fetal epithelial cells. Hence, modulation of glycoconjugate expression in the submandibular glands, which reflects changes in secretory cells from the fetal type to adult type during postnatal development, is revealed by lectin staining and immunostaining for SSEA-1 and related antigens.     

Differences in lectin binding in tissue sections of human and murine malignant tumors and their metastases.

Lectin binding to tumor cells in tissue sections of 16 nonmetastatic and 24 metastatic human adenocarcinomas and 5 nonmetastatic and 5 metastatic murine Lewis lung carcinomas (LLCs) was assessed with an avidin-biotin peroxidase technique. In human tumors, Ulex europaeus agglutinin I (UEA I) showed no binding; whereas concanavalin A (Con A), Ricinus communis agglutinin I (RCA I), wheat germ agglutinin (WGA), soybean agglutinin (SBA), and Dolichos biflorus agglutinin (DBA) bound equally to primaries and metastases. However, peanut agglutinin (PNA) bound to less than 5% of cells in 37 of 40 primaries but to greater than 50% of cells in 18 of 24 metastases. In LLC tumors, UEA I and DBA showed no binding; whereas Con A, RCA I, and WGA bound equally to primaries and metastases. SBA bound to greater than 50% of cells in 5 metastases but not to the 5 primaries. There was less than 5% binding of PNA to 10 primary murine tumors after neuraminidase pretreatment of tissue sections but greater than 50% binding in 3 of 5 metastases. These studies indicate, in both human adenocarcinomas and an experimental tumor system, that most tumor cells which metastasize show preferential binding of PNA and SBA.     

Histochemical Analysis of Changes in Lectin Binding in Murine Glomerular Lesions

Lectin binding in diseased murine glomeruli was studied in MRL 1 mice, using seven different fluorescence- or peroxidase coupled lectins: Griffonia simplicifolia I (GS-I) , Ulex europaeus agglutinin I (UEA-I) , Ricinus communis agglutinin I (RCA I), wheat germ agglutinin (WGA), concanavalin A (Con A), peanut agglutinin (PNA), and Helix pomatia agglutinin (HPA). Lectin binding in diseased glomeruli of MRL 1 mice was different from that in normal glomeruli. Light and fluorescence microscopy showed that: 1. in mesangial proliferative lesions, the binding of RCA I, WGA and Con A increased and that of GS I and PNA appeared in the mesangium; 2. in other glomerular lesions, UEA-I bindng appeared and RCA I stained the altered membranes irregularly. Electon microscopy showed that: 1. GS-I stained the endothelial cell coat and the glomerular basement membrane covered by the endothelial cells; 2. GS I strongly stained the dilated subendothelium in regions of mild mesangial interposition; 3. GS-I stained the cell coat of invasive macrophages; 4. GS-I and UEA-I stained the cell membrane-like material derived from degenerative endothelial cells; 5. RCA I stained the epithelial and endothelial cell coats and the glomerular basement membrane. These results indicate that lectin-binding studies can be used for analysis of glomerular lesions.     

外阴营养不良、外阴鳞状上皮细胞癌凝集素标记免疫组化分析

目的：探讨外阴营养不良增生型,硬化苔藓型表皮细胞和外阴鳞状上皮细胞癌等细胞膜结构与凝集素受体结合表达特征及它们三者之间的关系。方法：对慢性外阴营养不良表皮增生型,苔藓硬化型及外阴鳞状上皮细胞癌3种状态下的细胞进行了8种凝集素免疫组织化学标记,分析,比较。结果：外阴营养不良增生型表皮各层细胞细胞膜与刀豆凝集素（ConA),扁豆凝集素（LCA）,花生凝集素（PNA）,蓖麻凝集素（RCA－1）和大豆凝集素（SBA）结合强度弱,其表皮细胞细胞核膜与ConA,PNA和麦胚凝集素（WGA）有中等强度结合,外阴营养不良硬化苔藓型表皮各层细胞细胞膜与ConA,RCA-1 SBA和WGA结合强度弱,而与LCA不结合,其12例中的8例与荆豆凝集素（UEA－1）发生较弱的结合,外阴鳞状上皮细胞癌癌细胞与8种凝集素均结合,其12例中的7例其癌细胞膜与双花扁豆凝集素（DBA）弱结合,癌细胞膜与UEA－1强结合,但癌巢中央细胞团不与UEA－1结合,癌细胞细胞核膜与ConA,LCA,RCA-1呈强结合。结论：凝集素标记免疫组织化学染色可作为诊断,鉴别诊断外阴营养不良增生,硬化苔藓型和外阴鳞状上皮细胞癌新的指标,具有恶变潜能的增生型外阴营养不良与外阴鳞状上皮细胞癌,两者细胞核膜凝集素标记有相似之处,提示在外阴组织的癌变过程中,细胞核膜凝集素标记的异常表达是一个早期标识,糖基和糖蛋白代谢的异常可能是细胞发生癌变最早期的表现之一。     

Lectin histochemistry on the olfactory region and the vomeronasal organ or rats and golden hamsters]

The present investigation describes the lectin-binding properties of the regio olfactoria (RO) and the vomeronasal organ (VNO) of the rat and golden hamster. Special attention is paid to the lectin-binding properties of the chemosensory epithelia as well as to the reactions of their specific glands. The following lectins were used: wheat germ agglutinin (WGA), horseshoe crab agglutinin (LPA), gorse agglutinin (UEA I), peanut agglutinin (PNA), soybean agglutinin (SBA), and horse gram agglutinin (DBA). Lectin-binding procedure was performed on paraffin sections of the RO and VNO using the peroxidase-antiperodixase method. Comparisons of the lectin-binding properties of the surface of the main olfactory epithelium (MOE) with that of the neuroepithelium (NE) of the VNO as estimated by the intensity of staining demonstrate that in both species differences exist between the lectin-binding properties, of the MOE and VNO-NE. Moreover, some reactions of the MOE and VNO-NE differ from species to species.     

Histochemical analysis of changes in lectin binding in murine glomerular lesions

Lectin binding in diseased murine glomeruli was studied in MRL/1 mice, using seven different fluorescence- or peroxidase-coupled lectins: Griffonia simplicifolia I (GS-I), Ulex europaeus agglutinin I (UEA-I), Ricinus communis agglutinin I (RCA-I), wheat germ agglutinin (WGA), concanavalin A (Con A), peanut agglutinin (PNA), and Helix pomatia agglutinin (HPA). Lectin binding in diseased glomeruli of MRL/1 mice was different from that in normal glomeruli. Light and fluorescence microscopy showed that: 1. in mesangial proliferative lesions, the binding of RCA-I, WGA and Con A increased and that of GS-I and PNA appeared in the mesangium; 2. in other glomerular lesions, UEA-I binding appeared and RCA-I stained the altered membranes irregularly. Electron microscopy showed that: 1. GS-I stained the endothelial cell coat and the glomerular basement membrane covered by the endothelial cells; 2. GS-I strongly stained the dilated subendothelium in regions of mild mesangial interposition; 3. GS-I stained the cell coat of invasive macrophages; 4. GS-I and UEA-I stained the cell membrane-like material derived from degenerative endothelial cells; 5. RCA-I stained the epithelial and endothelial cell coats and the glomerular basement membrane. These results indicate that lectin-binding studies can be used for analysis of glomerular lesions.     

Lectin binding on carbohydrate compounds of the flask cells in the claw-frog kidney

The carbohydrate compounds of the mucus of flask cells in the kidney of claw-frogs (Xenopus laevis) were analysed through lectin binding studies. After removing epoxy resin semithin sections were incubated with 7 lectins (WGA, RCA I, PNA, LCH, UEA, LPA) marked by horseradish peroxidase and 2 unmarked lectins (VAA, Con A). The glycosaminoglycans in the canalicular lumen of flask cells showed a strong reaction with WGA and RCA, whereas the binding of PHA, Con A, and LCH was weaker. No reaction was observed with PNA, UEA, LPA, and VAA. The mucus of the flask cells seems to be rich in N-acetyl-glycosamine and -galactosamine. It contains also mannose, glucose, and galactose, but seems to have no fucose or N-acetyl-sialic acid residues.     

Effects of different fixatives on staining patterns of four lectins in cultured microvascular endothelial cells

Fixatives have significant influence on lectin histochemistry of tissue sections; however, their roles in lectin fluorescent staining of cultured cells remain unclear. In this study, using cultured microvascular endothelial cells (MVECs) from rat intestinal mucosa, the effects of seven fixatives on the fluorescent staining patterns of four lectins were investigated. The results indicated that every fixative gave concanavalin A (Con A) and wheat germ agglutinin (WGA) strong positive staining in different patterns. When fixed with Zenker’s, periodate–lysine–paraformaldehyde (PLP), 2·5% glutaraldehyde (GA), and 4% paraformaldehyde (PFA) solution, the cell membranes and cytoplasms stained, and the fluorescence in the cell edges was brighter. Rossman’s solution, 95% ethanol, and acetone fixation caused cytoplasmic staining, while the fluorescence was weak and evanescent when using acetone. Dolichos biflorus agglutinin (DBA) and Ulex europaeus agglutinin I (UEA I) were stained; revealing very faint fluorescence in cytoplasms just when PLP and 2·5% GA solution were used. In conclusion, this study shows that fixatives have significant effects on the fluorescent staining of MVECs. Fixatives containing aldehydes and mercury chloride are better options for cell membrane glycans, and those containing ethanol for cytoplasmic ones. Acetone fixation is not suitable for lectin histochemistry.     

Lectin-binding patterns of small lymphocytes in bone marrow,thymus and spleen: demonstration of lymphocyte subsets by quantitative radioautography

Cells from mouse bone marrow, thymus and spleen were exposed to ¹²⁵I-labeled concanavalin A (Con A), Lens culinaris lectin (LCL), soybean agglutinin (SBA), Helix pomatia agglutinin (HPA), phytohemagglutinin-P (PHA-P), peanut agglutinin (PNA), or wheat germ agglutinin (WGA) in a range of concentrations and examined radioautographically. Small lymphocytes in the three organs differed in the minimal concentration of each lectin which gave detectable surface labeling, while at optimal lectin concentrations, their labeling intensity profiles differed markedly. Inhibition by sugars demonstrated the labeling specificity. Major populations of bone marrow small lymphocytes bound WGA strongly, while Con A, SBA, HPA, PHA-P and LCL were bound only weakly, and PNA binding was lacking. Most thymus cells bound Con A, SBA, HPA, PHA-P and PNA strongly, WGA and LCL weakly. Subsets of bone marrow and thymus small lymphocytes differed from the major populations in their lectin-binding intensities. Spleen small lymphocytes were heterogeneous in the binding of each lectin. However, a major population bound LCL exceptionally strongly, while few cells bound PNA. Using a panel of lectins under standardized conditions, these studies show distinctive lectin-binding patterns for small lymphocytes in the bone marrow, thymus and spleen, respectively. Major and minor cell populations are distinguishable in each organ, providing an approach to discriminating lymphocyte lineages, subtypes and differentiation stages.     

Lectin-binding in normal and fibrillated articular cartilage of human patellae

Summary Fluorescein-isothiocyanate (FITC) labeled lectins were used to study the distribution of specific binding-sites in histological sections of normal and fibrillated articular cartilage of human patellae.It has been shown that normal articular cartilage reveals lectin binding-sites for Concanavalin A (Con A) and wheat germ agglutinin (WGA), but not for soybean agglutinin (SBA), peanut agglutinin (PNA) and Ulex europaeus agglutinin (UEA).In fibrillated cartilage the distribution pattern of Con A and WGA is completely changed. SBA, PNA and UEA show a distinct staining pattern in particular in the fibrillated areas of degenerated cartilage. Lectin-staining of the extracellular matrix and the chondrocytes in both normal and fibrillated cartilage did not show any correlation with material that was either PAS- or Alcian blue-positive. In comparison with the conventional PAS- and Alcian blue reaction lectin-staining proved to be superior.Visualization of intra- and extracellular glycoconjugate-changes in normal and fibrillated cartilage in areas with no PAS and/or Alcian blue staining indicates that all layers of the cartilage are involved in the pathological process.It is evident that lectins can demonstrate minute differences between normal and arthrotic cartilage and we therefore conclude that lectins are sensitive and specific tools for the study of degenerative joint diseases.     

Lectin histochemistry of palatine glands in the developing rat

This study examined the binding pattern of lectins, soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Ulex europaeus agglutinin-I (UEA-I), peanut agglutinin (PNA), wheat germ agglutinin (WGA), and succinylated WGA (sucWGA) in the developing rat palatine glands. In adult rats, heterogeneous lectin binding patterns were revealed between the anterior and posterior portions of palatine glands, as DBA, VVA, and WGA were bound more intensely and broadly in the posterior portion. SBA, PNA, and sucWGA showed far less reactivity in the anterior than in the posterior portion. At embryonic day 18 (E18), weak labeling was observed with UEA-I and WGA at the basal membrane of terminal buds, UEA-I and PNA labeled the epithelial cord, and there was no apparent binding for SBA, DBA, VVA, and sucWGA. At E20, after acinar lumenization, all lectins were detected at the acinar cell basal membranes. After birth, all lectins detectably labeled at the mucous cell apical membranes and progressively, with maturation, extended from the apical to basal portions of the cytoplasm. Apparent serous cells were observed around postnatal day 10 (PN10) and bound UEA-I. Lectins reached peak reactivity at PN21 and the binding patterns became identical to those of adults around PN28.     

Distribution of lectin receptors in postimplantation mouse embryos at 6–8 days gestation

We have examined the pattern of binding of eleven lectins—BSL-II, WGA, LPA, Con A, DBA, SBA, LTA, UEA-I, MPA, PNA, and RCA-I, with specificity for a range of saccharides, to postimplantation mouse embryos from 6 to 8 days of gestation. The lectins were used to stain sections of ethanol-fixed paraffin-embedded and formaldehyde-fixed gelatin-embedded embryonic material. Our observations reveal a complex pattern of lectin binding to both cell surfaces and cytoplasm. Many of the lectins bind particularly to the outer surface of visceral endoderm (e.g., DBA, WGA, SBA, and RCA-I) and to the surface of the proamniotic cavity (e.g., RCA-I, PNA, and WGA). In the newly formed mesenchyme of primitive-streak-stage embryos, galactose and N-Acneuraminic acid are present but lectins with specificity for other sugars either did not bind to the cells or bound only in small amounts.     

Lectinohistochemistry of human bladder cancer: loss of lectin binding structures in invasive carcinomas

With the purpose of studying changes in the expression of glycoconjugate structures in urothelium, nine different lectins (PNA, WGA, VFA, GSA II, STA, UEA I, LCA, DBA and HPA) with specificity for mono- or oligo-saccharides were used on formalin-fixed, paraffin-embedded tissue sections from 47 patients who had undergone surgical resection for bladder tumors and on normal urothelial biopsies from 10 patients. The tumors were graded and a lectinohistochemical method using biotinylated lectins and avidin-biotin-peroxidase complex was used to demonstrate the lectin binding. Positive staining reactions of cells in cytoplasm and on membranes were evaluated in the basal, the intermediate, and the luminal cell layers, respectively. In both normal and atypical urothelium lectin binding predominated in the luminal cell layer and decreased towards the basal cell layer. In normal urothelium all lectins stained greater than 66% of the cells in the luminal cell layer in cytoplasm and between 5 and 100% of the cells on membranes depending on the lectin used. A gradual loss of lectin-binding structures was seen with increasing grade of atypia. The range of this decrease varied considerably from one lectin to another, but it was consistently found that the percentage of cells stained in cytoplasm and on membranes decreased. A significantly lower percentage of cells stained in cytoplasm was found in invasive tumor cell-islands compared to normal urothelium. In invasive tumor cell-islands staining of cells on membranes was completely absent, except for HPA lectin that stained less than 10% of the cells. In conclusion, we demonstrate a dramatic decrease in lectin-binding carbohydrate structures associated with urothelial malignant progression.