Lectin histochemistry on squamous metaplasia in different epithelial tumors of dogs

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 histochemistry of dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats

A lectin histochemical study was carried out on the dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats (HtRs) and Wistar rats (WRs) at 3, 7 and 24 weeks of age to clarify the lectinhistochemical characteristics of the skin during their development. The lectins examined were Concanavalia ensiformis (Con A), Dolichos biflorus agglutinin (DBA), Griffonia simpliciolia (GS-I), Helix pomatia agglutinin (HPA), Arachis hypogaea (PNA), Glycine maximus agglutinin (SBA), Ulex europeus agglutinin (UEA-I) and Triticum vulgaris agglutinin (WGA). None of the nucleated cell layers of the epidermis had DBA-binding sites, but they were all stained intensely with HPA and weakly with Con A irrespective of the strain and age of the rats. As to the other 5 lectins, the intensity of binding activity was generally weaker in HtRs than in WRs and at 3 weeks of age than at 7 or 24 weeks of age, respectively. Among them, UEA-I mainly bound to the spinous cell layer but not to the basal cell layer, suggesting that alpha-L-fucose would be expressed on the cell surface according to the differentiation of keratinocytes. In addition, GS-I, HPA and UEA-I bound to the hair follicle epithelium and many lectins stained sebaceous gland epithelial cells. In conclusion, except for the binding intensity of some lectins, there were no specific differences between HtRs and Wrs in the lectinhistochemical characteristics of the dorsal skin epidermis. The present data on the rat skin would be useful from the viewpoint of comparative lectinhistochemistry.

Morphological and biochemical investigations of mitral valve endocardiosis in pigs

Pig endocardiosis is a pathological process affecting cardiac valves that is characterised by the accumulation of glycosaminoglycans (GAG) in the extracellular matrix. To investigate the involvement of GAG in the condition, the morphology of the mitral valves from 23 affected pigs and seven normal controls was studied and qualitative and quantitative biochemical analyses of GAG were made. Gross and histopathological lesions were characterised by valve enlargement, collagen disorganisation and myxoid degeneration. No differences between normal and diseased valves were detected by lectin histochemistry. Electron microscopy revealed myofibroblast differentiation of many fibroblasts. A statistically significant increase of total GAG and hyaluronan was detected in the mitral valves of the pigs with endocardiosis by spectrophotometric, electrophoretic and densitometric analysis of the extracted GAG. Although it is not known whether the change in hyaluronan is a primary event or a result of other changes in the extracellular matrix, its accumulation in association with myofibroblast differentiation suggests that it plays a pathogenetic role in pig endocardiosis.

Intermediate filament expression and lectin histochemical features of canine transmissible venereal tumour

Immunocharacterization of intermediate filament proteins and lectin-binding studies were carried out in canine transmissible venereal tumour (TVT), a unique neoplasia sharing some epidemiological features with Kaposi's sarcoma in humans. Neoplastic cells express vimentin, but neither cytokeratin nor desmin. Regarding lectins, TVT cells express receptors for Triticum vulgaris (WGA), Concanavalia ensiformis (Con A) and Ricinus communis I (RCA-I). They appear to be negative for Ulex europaeus-I (UEA-I), Arachis hypogaea (PNA), Glycine maximus (SBA) and Dolichos biflorus (DBA).

Lectin histochemistry on the skin of hairless descendants of Mexican hairless dogs

The skin of hairless descendants of Mexican hairless dogs was investigated lectin-histochemically. Haired dogs were also used for comparative study. In the epidermis of infant pups, lectin staining revealed marked differences between hairless and haired dogs. Griffonia simplicifolia-I (GS-I) bound moderately to the cytoplasm of the stratum basale of hairless dogs, while no binding to that of haired dogs was observed. Bauhinia purpurea (BPA) showed positive staining for the stratum spinosum and basale of hairless dogs, while it was negative or weakly positive for the cytoplasm of both epidermal layers of haired dogs. Maclura pomifera (MPA) showed moderate to intense staining for the intercellular area of the stratum basale of hairless dogs, while no or weak staining was detected in that of haired dogs. Urex europeus-I (UEA-I) bound weakly to moderately to the cytoplasm and the intercellular area of the stratum spinosum of hairless dogs, whereas no or very weak staining was observed in those of haired dogs. Most of the lectins exhibited significant alterations in the epidermal staining pattern between infants and adults. Significant differences were not observed in adult canine epidermis between hairless and haired dogs. In conclusion, lectin histochemistry in hairless dogs revealed that there were different development steps in the epidermal cells between infants and adults.