A lectin histochemical study on the testis of the babirusa, Babyroussa babyrussa (Suidae)

The distribution of lectin bindings in the testis of babirusa, Babyrousa babyrussa (Suidae) was studied histochemically using 10 biotinylated lectins, Peanut agglutinin (PNA), Ricinus communis agglutinin (RCA I), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Soybean agglutinin (SBA), Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Pisum sativum agglutinin (PSA), Concanavalin A(Con A) and Ulex europaeus agglutinin (UEA I). Nine of 10 lectins showed a variety of staining patterns in the seminiferous epithelium and interstitial cells. The acrosome of Golgi-, cap- and acrosome-phase spermatids displayed various PNA, RCA I, VVA, SBA and WGA bindings, indicating the presence of glycoconjugates with D-galactose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine sugar residues respectively. No affinity was detected in the acrosome of late spermatids. LCA, PSA and Con A which have affinity for D-mannose and D-glucose sugar residues were positive in the cytoplasm of spermatids and spermatocytes. DBA was positive only in spermatogonia. In addition to DBA, positive binding in spermatogonia was found for VVA, WGA and Con A, suggesting the distribution of glycoconjugates with N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, D-mannose and D-glucose sugar residues. Sertoli cells were stained intensely with RCA I, WGA and Con A. In Leydig cells, RCA I and Con A were strongly positive, while WGA, LCA and PSA reactions were weak to moderate. The present findings showed that the distribution pattern of lectin binding in the testis of babirusa is somewhat different from that of pig or other mammals reported previously.     

Histochemical Analysis of Glycoconjugates in the Skin of a Catfish (Arius Tenuispinis, Day)

A histochemical study using conventional carbohydrate histochemistry (periodic‐acid staining including diastase controls, alcian blue staining at pH 1 and 2.5) as well as using a battery of 14 fluorescein isothiocyanate (FITC)‐labelled lectins to identify glycoconjugates present in 10 different areas of the skin of a catfish (Arius tenuispinis) was carried out. The lectins used were: mannose‐binding lectins (Con A, LCA and PSA), galactose‐binding lectins (PNA, RCA), N‐acetylgalactosamine‐binding lectins (DBA, SBA, SJA and GSL I), N‐acetylglucosamine‐binding lectins (WGA and WGAs), fucose‐binding lectins (UEA) and lectins which bind to complex carbohydrate configurations (PHA E, PHA L). Conventional glycoconjugate staining (PAS staining, alcian blue at pH 1 and 2.5) showed that the mucous goblet cells contain a considerable amount of glycoconjugates in all locations of the skin, whereas the other unicellular gland type, the club cells, lacked these glycoconjugates. The glycoproteins found in goblet cells are neutral and therefore stain magenta when subjected to PAS staining. Alcian blue staining indicating acid glycoproteins was distinctly positive at pH 1, but gave only a comparable staining at pH 2.5. The mucus of the goblet cells therefore also contains acid glycoproteins rich in sulphate groups. Using FITC‐labelled lectins, the carbohydrate composition of the glycoproteins of goblet cells could be more fully characterized. A distinct staining of the mucus of goblet cells was found with the mannose‐binding lectins LCA and PSA; the galactosamine‐binding lectins DBA, SBA and GLS I; the glucosamine‐binding lectin WGA; and PHA E which stains glycoproteins with complex carbohydrate configurations. No reaction occurred with the fucose‐binding lectin UEA and the sialic acid‐specific lectin SNA. In addition, the galactose‐binding lectins PNA and RCA showed only a weak or completely negative staining of the mucus in the goblet cells. The specificity of the lectin staining could be proved by inhibiting binding of the lectins by competitive inhibition with the corresponding sugars. From these data, we can conclude that the mucus produced by the epidermal goblet cells of A. tenuispinis is rich in mannose, N‐acetylgalactosamine and N‐acetylglucosamine residues.     

Histochemical Detection of Glycoconjugates in the Canine Epididymis

A histochemical study using fluorescein isothiocyanate (FITC)-labelled lectins to identify glycoconjugates present in the efferent ductules and the three segments of the ductus epididymis (initial, middle and terminal segment) of dogs was carried out. The lectins used were: mannose-binding lectins (Con A, LCA and PSA), galactose-binding lectins (PNA, RCA), N -acetylgalactosamine-binding lectins (DBA, SBA, SJA and GSL I), N -acetylglucosamine-binding lectins (WGA and WGAs), fucose-binding lectins (UEA) and lectins which bind to complex carbohydrate configurations (PHA E and PHA L). The lectin-binding pattern in the canine epididymis presents similarities and differences to those observed in other mammalian species. The ductuli efferentes distinctly stained with most of the lectins used, whereas in the ductus epididymis a segment specific staining pattern was observed. Whereas principal cells of the ductus epididymis stained clearly with several FITC-labelled lectins (WGA, UEA and PHA-L), basal cells showed only a significant binding of Con A.     

Lectin‐binding Sites on the Normal and Pathologic Uterus of Sows

The lectin‐binding pattern was compared in the normal and pathological uterus of sows during the ovarian cycle. The following biotinylated lectins were used: Con A, DBA, SBA, PNA, RCA‐I, UEA‐I and WGA. Glycoconjugate labelling showed differences between phases of ovarian cycle and presence of morphologic lesions. Cystic endometrial hyperplasia increased the RCA‐I reaction in the apical region of the glandular epithelium. There was higher intensity of labelling of WGA in the glandular epithelium in uteri with endometritis. In addition, increased Con A binding in the glandular epithelium and mild reduction of UEA‐I reactivity in the glycocalyx of the glandular epithelium were detected in the cases of endometritis. The results of this study show that morphologic alterations modify the sugar pattern in the porcine uterus. These modifications in glycoconjugates may be one of the reasons for decreased fertility in sows.     

Lectin‐Binding Pattern in Ovarian Structures of Rats with Experimental Polycystic Ovaries

Numerous experimental models in different species have been developed for the study of polycystic ovarian syndrome. In this study, we used a model of induction of polycystic ovaries (PO) in rats by exposure to constant light to study the distribution and variations of glycosylated residues present in the different ovarian structures. Seven biotinylated lectins were used (Con‐A, WGA, DBA, SBA, PNA, RCA and UEA‐I) on tissue sections, and detection was performed using the streptavidin/peroxidase method. In tissue sections was observed an increase in affinity for Con‐A in the granulosa and theca interna of growing follicles and cysts in animals with PO in relation to the control group. Follicular cysts showed higher affinity for WGA and RCA‐I which growing follicles in the same group, and there was a decrease in affinity for PNA in the cysts in relation to the growth of follicles in both groups. Atretic follicles in both groups showed greater labelling with lectins PNA, SBA and RCA‐I in relation to healthy follicles. It could also be noted that the zona pellucida of cystic follicles lost the affinity for the lectin Con‐A. There was no staining on follicles in any category with the lectins DBA and UEA‐I, although it was staining in the corpus luteum (control group) and in the mesothelium and interstitial glands of both groups with DBA. These observations probably reflect changes in the glycosaminoglycans present in the different ovarian compartments or in the glycosylation of cellular components essential for proper follicular dynamics.     

A lectin histochemical study of the zygomatic salivary gland of adult dogs

Seven lectins (PNA, DBA, SBA, UEA I, LTA, WGA and ConA), conjugated with horseradish peroxidase, were used to characterize the glycosidic residues in the zygomatic gland of adult dogs. In some cases (PNA and DBA), lectin staining was preceded by neuraminidase digestion. The acinar and tubular cells produced glycoconjugates with different sugar residues, presenting binding sites for all of the lectins used. The apical surfaces of the cells lining the intra- and interlobular ducts were also stained by all the lectins. In contrast, the demilunar cells only reacted with the Neu-PNA sequence and Con A. Abbreviations: Neu, neuraminidase; see also Table I     

Effects of inflammation and aqueous tear film deficiency on conjunctival morphology and ocular mucus composition in cats

An experimental model of keratoconjunctivitis sicca (KCS) was produced by removing the lacrimal gland and the gland of the third eyelid from the left eye of 6 cats. The right eye of each cat was left intact and used as a control. After 2 weeks, cats were euthanatized and the central portion of the upper eyelid from both eyes of each cat was excised. Histologic sections were stained with either hematoxylin and eosin or with a battery of biotinylated lectins including concanavalin A (conA), soybean agglutinin (SBA), wheat germ agglutinin (WGA), succinylated wheat germ agglutinin (S-WGA), Ulex europaeus agglutinin I (UEA), Dolichos biflorus agglutinin (DBA), Ricinus communis agglutinin (RCA), peanut agglutinin (PNA), and PNA pretreated with neuraminidase. Consistent differences in histologic features were not observed between conjunctivas with KCS and control conjunctivas. A variable degree of mononuclear cell infiltration of the substantia propria was observed in control conjunctivas and those with KCS. In both groups, conjunctival goblet cell density decreased and epithelial stratification increased as the degree of submucosal inflammatory cell infiltration increased. Lectin binding sites for DBA, WGA, S-WGA, UEA, PNA, and PNA pretreated with neuraminidase were detected on conjunctival goblet cells of conjunctivas with KCS and control conjunctivas. The mucus/glycocalyx layer of conjunctival epithelial cells in both groups of conjunctivas bound lectins RCA, WGA, UEA, and conA, but inconsistently bound S-WGA. In both groups, DBA principally bound to the mucus layer overlying normal epithelium, whereas PNA pretreated with neuraminidase consistently bound to the mucus layer of stratified epithelial surfaces free of goblet cells. Binding of SBA to goblet cells and the mucus/glycocalyx layer was variable.     

Lectin histochemical pattern on the normal and cystic ovaries of sows

The lectin histochemical pattern (LHP) was characterized and compared in normal and cystic ovaries of sows. Six biotinylated lectins (PNA, SBA, WGA, RCA‐1, DBA and UEA‐1) were used on tissue sections. In the normal ovaries, the reaction to UEA‐1 and SBA was mild to moderate in mesothelial and endothelial cells. RCA‐1 staining was mild to moderate in theca interna of growing follicles, corpora luteum and mesothelium. In addition, this lectin presented strong reaction in endothelial cells, granulosa cells of atretic follicles, zona pellucida of growing follicles and plasma. DBA showed strong intensity in mesothelial and endothelial cells. There was mild to moderate reactivity to WGA in granulosa cells, corpus luteum and theca interna of follicles in development, and moderate in zona pellucida, in granulosa cells of atretic follicles and mesothelium. PNA staining was mild to moderate in oocytes and in the adventitia and media of medullary arteries. Changes in the LHP of the cystic ovaries were noted; however, there were no differences in these findings between the follicular and luteinized cysts. UEA‐1 reactivity in the cystic ovaries was moderately reduced in the mesothelial and endothelial cells, whereas there was mild reduction in the DBA staining in the granulosa cells. Reaction to RCA‐1 and WGA in the cysts also was decreased in theca interna, zona pellucida and granulosa cells of atretic follicles. Furthermore, endothelium and theca interna in the cystic ovaries presented mild reduction of marcation to SBA, whereas there was decreased reactivity to PNA in the oocytes and adventitia and media layers of the medullary arteries. The results of the current study show that cysts modify the LHP in swine ovaries. These changes of glycoconjugates in many ovarian structures could modify diverse process and may be one of the reasons for decreased fertility in sows.     

Localization of the lectin reactive sites in adult and prepubertal horse testes

The testes of prepubertal and adult horses were investigated using 10 horseradish peroxidase conjugated lectins combined with sialidase digestion and potassium hydroxide treatment, to localise the oligosaccharide sequences of glycoconjugates during spermatid maturation. In adult animals, the lectins showed a variable affinity for spermatids and Sertoli cell apical extensions. Soybean agglutinin (SBA), peanut agglutinin (PNA), Ricinus communis agglutinin (RCA-I) and wheat germ agglutinin (WGA) bound to the acrosomal structures of spermatids, whereas Griffonia simplicifolia agglutinin (GSA-II) labelled these structures only during Golgi and cap phases. These results suggested that glycoproteins of mature acrosomes contain both N- and O-linked oligosaccharides and that these carbohydrate chains undergo modifications during spermiogenesis. Sialic acid residues were not detected throughout the acrosomal development. The lectin binding pattern of Sertoli cells was very similar to that of acrosome of spermatids during the maturation phase. In sexually immature horses, only the degenerated germinal cells and the Leydig cells showed reactivity towards lectins. The first cells reacted with SBA and Dolichos biflorus agglutinin (DBA), the latter with SBA, PNA, WGA, GSA-II, Canavalia ensiformis agglutinin (ConA), Lens culinaris agglutinin (LCA) and also with DBA after sialidase digestion.     

Lectin Histochemistry as a Tool to Identify Apoptotic Cells in the Seminiferous Epithelium of Syrian Hamster (Mesocricetus auratus) Subjected to Short Photoperiod

Lectins have been widely used to study the pattern of cellular glycoconjugates in numerous species. In the process of cellular apoptosis, it has been observed that changes occur in the membrane sugar sequences of these apoptotic cells. The aim of our work was to identify which lectins, out of an extensive battery of the same (PNA, SBA, HPA, LTA, Con‐A, UEA‐I, WGA, DBA, MAA, GNA, AAA, SNA), show affinity for germinal cells in apoptosis, at what stage of cell death they do so and in which germinal cell types they can be detected. For this, we studied testis sections during testicular regression in Syrian hamster (Mesocricetus auratus) subjected to short photoperiod. Several lectins showed an affinity for the glycoconjugate residues of germ cells in apoptosis: Gal β1,3‐GalNAcα1, α‐d ‐mannose, N‐acetylgalactosamine and l ‐fucose. Furthermore, lectin specificity was observed for some specific germinal cells and in certain stages of apoptosis. It was also observed that one of these lectins (PNA) showed affinity for Sertoli cells undergoing apoptosis. Therefore, we conclude that the use of lectin histochemistry could be a very useful tool for studying apoptosis in the seminiferous epithelium because of the specificity shown towards germinal cells in pathological or experimentally induced epithelial depletion models.     

Original Papers

In the present study we report on the histotopographical distribution of lectin binding sites in the trophoblasts of day 18 to day 40 bovine embryos, using the FITC-labeled lectins BPA, Con A, DBA, GS I, GS II, MPA, PNA, SBA, UEA I and WGA. Lectin binding sites localized in giant binucleate cells differ from those localized in uninucleate cells, indicating changes in the biochemical structure of cell surfaces taking place during differentiation. In the trophoblast of the day 40 embryo, a distinct staining of uninucleate cells was seen after incubation with GS I, Con A and MPA, demonstrating N-acetylgalactosamine (GS I), Mannose (Con A) and Galactose (MPA) moieties, whereas giant binucleate cells showed intense reactions after incubation with DBA and WGA, indicating presence of N-acetylgalactosamine (DBA) and N-acetylglucosamine (WGA). GS II (specific for N-acetylglucosamine), SBA (specific for N-acetylgalactosamine) and UEA I (specific for L-Fucose) showed no affinity toward any of the examined tissues. We assume, that carbohydrate moieties in trophoblast cells play an important role in fetomaternal cell-cell adhesion and cell migration during implantation and placentation period.     

Role of glycoconjugates in adherence of Salmonella pullorum to the intestinal epithelium of chicks

1. The distribution of glycoconjugates on the surface of Salmonella pullorum and the ileal epithelium of chicks was demonstrated by lectin cytochemistry. The role of glycoconjugates in adherence of S. pullorum to the ileal epithelium was determined by a sugar inhibition assay using the scanning electron microscope.

2. S. pullorum exhibited binding to Concanavalin A (Con A) and wheat germ agglutinin (WGA) but not to soyabean agglutinin (SBA), Ricinus communis agglutinin (RCA) and Ulex europaeus agglutinin (UEA).

3. The ileal epithelium of chicks bound WGA, Con A and SBA. The binding sites for WGA were on the brush border and cytoplasm of columnar enterocytes as well as on goblet cells. The binding of Con A was confined to the cytoplasm of columnar enterocytes, while SBA bound, in a limited way, to the brush border of columnar enterocytes.

4. After an oral dose of S. pullorum, adherence to the ileal epithelium was inhibited by methyl α‐D‐mannopyranoside.     

A lectin histochemical study of the thoracic respiratory air sacs of the fowl

The lectin-binding characteristics of the epithelial lining of the thoracic air sacs of the chicken were determined. Con A, LCA and PSA bound to the apical membrane as well as to the cytoplasm distal to the nucleus of the surface epithelium, indicated the presence of a-linked mannose as well as N-acetylchitobiose-linked alpha-fucose residues in the glycoproteins. GSL I bound to the apical membrane and cytoplasm distal to the nucleus, but not to the cilia of the epithelium, where-as MPL, DBA and RCA120 bound to the apical membrane, cilia and cytoplasm, indicated the presence of a-linked N-acetylgalactosamine residues. However, neither SJA or SBA showed any binding, indicating the absence of beta anomers of galactosyl (beta1.3)N-acetylgalactosamine and beta-linked N-acetylgalactosamine residues. UEA I bound to the apical membrane and cilia, as well as to the cytoplasm of a few cells, indicated the presence of alpha-linked fucose residues. PNA bound to the apical membrane of some, but not all, surface epithelium cells, indicated the presence of galactosyl (beta1.3)N-acetylgalactosamine residues. WGA bound to the apical membrane and cilia, as well as to the cytoplasm of a few cells, indicated the presence of neuraminic acid residues.     

Preliminary Results Concerning the Expression of Carbohydrates in the Olfactory System of the Sturgeon

Lectins have been used in several areas of biomedicine and are particularly useful for histochemistry. Their ability to map the distributions of various kinds of cell- borne glycan, and thereby to identify particular cell populations, has allowed clarification of a number of issues in neuroscience. In the case of the olfactory system, for example, lectins may be involved in development, in the continual regeneration of olfactory neurons and even in the processing of olfactory information. Whereas in mammals and amphibians lectins have been widely employed for the study of the olfactory and accessory olfactory systems, little information regarding lectin labelling is available in fish. We have used a panel of 11 lectins (UEA, BSI-B₄, DBA, LEA, VVA, SBA, PSA, WGA, WGA-s, ECA, LTA) in paraformaldehyde fixed and paraffin embedded specimens of a Chondrostei fish, the sturgeon ( Acipenser baeri ). Our preliminary findings show that the olfactory receptor cells, the olfactory nerve fibres and their terminals in the olfactory bulbs were labelled with BSI-B₄, DBA, VVA, SBA, PSA, WGA and WGA-s. The presence of glycoproteins, whose terminal sugars are detected by lectin binding, might be related to the reception of an odour stimulus and its transduction into a nervous signal or to the histogenesis of the olfactory system.     

Heterogeneous expression of glycoconjugates in the primary olfactory centre of the Japanese sword‐tailed newt (Cynops ensicauda)

Histochemical organization of the Caudata olfactory system remains largely unknown, despite this amphibian order showing phylogenetic diversity in the development of the vomeronasal organ and its primary centre, the accessory olfactory bulb. Here, we investigated the glycoconjugate distribution in the olfactory bulb of a semi‐aquatic salamander, the Japanese sword‐tailed newt (Cynops ensicauda), by histochemical analysis of the lectins that were present. Eleven lectins showed a specific binding to the olfactory and vomeronasal nerves as well as to the olfactory glomeruli. Among them, succinylated wheat germ agglutinin (s‐WGA), soya bean agglutinin (SBA), Bandeiraea simplicifolia lectin‐I (BSL‐I) and peanut agglutinin showed significantly different bindings to glomeruli between the main and accessory olfactory bulbs. We also found that s‐WGA, SBA, BSL‐I and Pisum sativum agglutinin preferentially bound to a rostral cluster of glomeruli in the main olfactory bulb. This finding suggests the presence of a functional subset of primary projections to the main olfactory system. Our results therefore demonstrated a region‐specific glycoconjugate expression in the olfactory bulb of C. ensicauda, which would be related to a functional segregation of the olfactory system.     

Glycomolecule Modifications in the Seminiferous Epithelial Cells and in the Acrosome of Post‐testicular Spermatozoa in the Alpaca

A lectin histochemical investigation of the seminiferous epithelium and acrosomes of spermatozoa present in the efferent ductules and epididymal regions was carried out in the alpaca. The histochemical characterization was performed using a battery of different lectins: Con‐A, UEA‐I, LTA, WGA, GSA‐IB4, SBA, PNA, ECA, DBA, MAL‐II and SNA. Sialidase digestion and deglycosilation pre‐treatments were also employed. The cytoplasm of the Sertoli cells contained N‐linked oligosaccharides with α‐d ‐Man/α‐d ‐Glc and GlcNAc and O‐linked glycans with α‐l ‐Fuc, β‐GalNAc, β‐d ‐Gal‐(1‐4)‐d ‐GlcNAc, α–Gal and Neu5Acα2,6α‐GalNAc moieties whereas β‐d ‐Gal‐(1‐3)‐d ‐GalNAc residues were included in both O‐ and N‐glycoproteins. Spermatogonia expressed α‐d ‐Man/α‐d ‐Glc residues included in N‐glycoproteins and α‐Fuc in O‐glycoproteins. Spermatocytes contained the N‐glycoproteins residues α‐d ‐Man/α‐d ‐Glc and GlcNAc and the O‐glycoproteins residues α‐l ‐Fuc, β‐d ‐Gal‐(1‐4)‐d ‐GlcNAc, α–Gal, β‐GalNAc, Neu5Acα2,6α‐GalNAc and Neu5Acα2,6β‐d ‐Gal‐(1‐3)‐d ‐GalNAc. The results of the present study show differences in the presence and distribution of lectin reactive sites throughout the acrosomal development in the alpaca. In particular, Fuc moieties were found only during the Golgi‐phase of spermatids, α‐Gal were found in the acrosome of Golgi‐ and cap‐phase spermatids, sialic‐acid/α‐GalNAc sequence was revealed during the cap‐phase and elongated spermatids, and α‐d ‐Man/α‐d ‐Glc and GlcNAc were detected only in the acrosomes of elongated spermatids. Finally, β‐GalNAc, β‐d ‐Gal‐(1‐3)‐d ‐GalNAc and β‐d ‐Gal‐(1‐4)‐d ‐GlcNAc were added to acrosomal glycoproteins in the early stages of spermatogenesis and remained unchanged during the later phases. Differences in the carbohydrate expression were also demonstrated on the sperm acrosomes during passage through the post‐testicular ducts.     

Lectin histochemical characteristics of the canine female mammary gland.

Twelve biotinylated lectins and an avidin-biotin-peroxidase method were used to detect and localize specific carbohydrate residues on formalin-fixed, paraffin-embedded female canine mammary gland sections. Histologic sections from 3 lactating and 7 nonlactating mixed-breed dogs (age 5.6 +/- 0.35 years) were incubated with Arachis hypogea agglutinin (peanut agglutinin; PNA), Concanavalia ensiformis agglutinin (conA), Dolichos biflorus agglutinin (DBA), Glycine max agglutinin (SBA), Griffonia simplicifolia agglutinin-I (GS-I), Lens culinaris agglutinin (LCA), Lycopersicon esculentum agglutinin (LEA), Phytolacca americana mitogen (pokeweed mitogen; PWM), Ricinus communis agglutinin-I and -II (RCA-I and -II), Triticum vulgaris (WGA), and Ulex europaeus agglutinin-I (UEA-I). Each lectin had a specific binding pattern, except SBA and DBA. In nonlactating glands, PNA, conA, LEA, and UEA-I stained duct cells in a linear-binding pattern, with a mean percentage of positive ducts per section of 28.7 (+/- 0.6), 65.7 (+/- 0.3), 100 (+/- 0), and 8.4 (+/- 0.2), respectively. Strong apical, lateral, basal, and cytoplasmic positivity on duct cells was seen after incubation of the sections with RCA-I, RCA-II, and WGA in all ducts. In acinar cells, the binding pattern and the staining distribution of all the lectins studied were similar to those in duct cells. However, for PNA, conA, and UEA-I, the mean percentage of positive lobules per section was 33.7 (+/- 0.9), 62 (+/- 0.5), and 10.5 (+/- 0.2), respectively. In glands from lactating dogs, conA and UEA-I did not stain. The cytoplasm of all myoepithelial cells was moderately stained with RCA-I, RCA-II, and WGA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lectin binding pattern of gastric mucosa of pacific white-sided dolphin, Lagenorhynchus obliquidens

The stomach of the Pacific white-sided dolphin is divided into three parts: forestomach, proper gastric gland portion, and pyloric chamber. The histological features of the dolphin stomach are similar to those of terrestrial mammal stomachs, although the distribution of glycoconjugates in mucosal cells of the dolphin stomach is unknown. To learn about glycoconjugates in cetacean gastric mucosa, the glycoconjugate distribution in the mucous epithelium of the Pacific white-sided dolphin was studied using 21 lectins. Among the lectins tested, GSL-I and DBA specifically labelled the superficial layer of the forestomach epithelium. GSL-I, SBA, RCA-I, VVA, GSL-II, DSL, LEL, STL, s-WGA, WGA, PNA, and Jacalin labelled the luminal surface of the chief cells in the proper gastric gland. GSL-I, SBA, RCA-I, DSL, LEL, STL, s-WGA, PNA, and LCA labelled tubular structures in the cytoplasm of parietal cells. The surface portion of the pits in the pyloric chamber strongly reacted with RCA-I, GSL-II, WGA, PNA, LCA, PHA-L, and UEA-I, whereas the neck portion reacted weakly. Although lining one tubular portion, individual secretory cells in the pyloric gland displayed a heterogeneous reaction. This is the first report on the lectin histochemistry of a cetacean stomach and reveals GSL-I and DBA as specific marker lectins for the cornified stratified squamous epithelium cells of the Pacific white-sided dolphin. The stomachs of cetaceans and terrestrial mammals have similar histological features and mucous glycoconjugate content.     

Basic and Lectin Histochemical Characterization of Bovine Gustatory (von Ebner's) Glands

The Bovine tongue possesses numerous circumvallate papillae (8–16) each side). The troughs around the papillae are the openings of the ducts of the gustatory (von Ebner's) glands. In this study, we have characterized in situ the glycosidic composition of the secretion of bovine gustatory glands using traditional histochemical methods and lectin histochemistry with and without prior neuraminidase (sialidase) digestion. The lectin-horseradish peroxidase conjugates employed were: PNA, DBA, SBA, WGA, LTA, UEA I and ConA. Acinar cells show a diffuse positivity towards PAS and Alcian blue at pH 2.5 and the most intense and homogeneous lectin staining was obtained with PNA. This indicates that bovine gustatory glands secrete glycoproteins with 1,2-glycol containing hexoses and carboxyl-rich glycoconjugates and that galactosyl (β1 → 3) Nacetylgalactosamine is the most frequent sugar residue present in these glycoproteins. Results were compared with data reported in the literature on the same glands of other species.     

Detection of Glycosylated Proteins in Rabbit Oviductal Isthmus and Uterine Endometrium During Early Embryo Development

In this study, lectin histochemistry was performed on paraffin sections to compare carbohydrate expression of oviductal isthmus and uterine endometrium in rabbits during early embryo development. Rabbit embryos are surrounded not only by the zona pellucida but also by tubal secretion‐derived mucinous coat material, the mucin coat. Twenty sexually mature females were euthanized at 0 (pre‐ovulatory group) and 24, 72 and 96 h after insemination (pseudopregnancy group). The following lectin‐binding agents were used: Arachis hypogaea, Peanut (PNA) to label galactosyl (β‐1,3)N‐ acetyl‐galactosamine, Dolichos biflorus Agglutinin (DBA) to label galactosyl (β‐1,4)N‐ acetyl‐galactosamine, Lens curinaris (LCA) to label α‐‐mannose, α‐d ‐glucose and Pisum sativum agglutinin (PSA) to label α‐d ‐mannose, α‐d ‐glucose. Blood was collected by cardiac puncture, and direct enzyme immunoassay technique was used to measure progesterone concentration. A significant increase in total plasma progesterone concentrations was detected at 96 h post‐ovulation when compared with 0, 24 and 72 h post‐ovulation (2.9 ± 0.5 vs 0.5 ± 0.15, 1.6 ± 0.5 and 1.5 ± 0.4 ng/ml, at 96 h vs 0, 24 and 72 h post‐ovulation, respectively). No differences between pre‐ovulatory and pseudopregnant females were observed for glycoprotein localization in isthmus. In contrast, in the endometrium, differences in the glycoprotein detection between pre‐ovulatory and pseudopregnant stages were detected. PNA to label galactosyl (β‐1,3)N‐ acetyl‐galactosamine was not detected at the pre‐ovulatory stage, but its presence was detected at 24 h after ovulation. Both PSA and LCA to label α‐d ‐mannose, α‐d ‐glucose were only detected at 72 h after ovulation. DBA detection was similar for all stages of the reproductive cycle. Therefore, N‐acetyl‐galactosamine secreted from isthmus could be involved in the formation of the embryonic mucin coat. d ‐galactose (PNA), d ‐glucose and d ‐mannose (PSA and LCA) might be crucial for the implantation period.