Histological and lectin histochemical studies on the olfactory mucosae of the Korean roe deer, Capreolus pygargus

Olfactory epithelium and ontogeny of the nasal chambers in the bowhead whale (Balaena mysticetus)

In a species of baleen whale, we identify olfactory epithelium that suggests a functional sense of smell and document the ontogeny of the surrounding olfactory anatomy. Whales must surface to breathe, thereby providing an opportunity to detect airborne odorants. Although many toothed whales (odontocetes) lack olfactory anatomy, baleen whales (mysticetes) have retained theirs. Here, we investigate fetal and postnatal specimens of bowhead whales (Balaena mysticetus). Computed tomography (CT) reveals the presence of nasal passages and nasal chambers with simple ethmoturbinates through ontogeny. Additionally, we describe the dorsal nasal meatuses and olfactory bulb chambers. The cribriform plate has foramina that communicate with the nasal chambers. We show this anatomy within the context of the whole prenatal and postnatal skull. We document the tunnel for the ethmoidal nerve (ethmoid foramen) and the rostrolateral recess of the nasal chamber, which appears postnatally. Bilateral symmetry was apparent in the postnatal nasal chambers. No such symmetry was found prenatally, possibly due to tissue deformation. No nasal air sacs were found in fetal development. Olfactory epithelium, identified histologically, covers at least part of the ethmoturbinates. We identify olfactory epithelium using six explicit criteria of mammalian olfactory epithelium. Immunohistochemistry revealed the presence of olfactory marker protein (OMP), which is only found in mature olfactory sensory neurons. Although it seems that these neurons are scarce in bowhead whales compared to typical terrestrial mammals, our results suggest that bowhead whales have a functional sense of smell, which they may use to find prey.

Glycan diversity in the vomeronasal organ of the Korean roe deer, Capreolus pygargus: A lectin histochemical study

Glycans in the epithelium play an important role in cell-to-cell communication and adhesion. No detailed evaluation of glycoconjugates in the vomeronasal organs (VNO) of the roe deer has been published previously. The aim of this study was to characterize glycan epitopes in the vomeronasal sensory epithelium (VSE) and non-sensory epithelium (VNSE) using lectin histochemistry. Glycan epitopes identified by lectin histochemistry were grouped as follows: N-acetylglucosamine (s-WGA, WGA, BSL-II, DSL, LEL, STL), mannose (Con A, LCA, PSA), galactose (RCA₁₂₀, BSL-I, Jacalin, PNA, ECL), N-acetylgalactosamine (VVA, DBA, SBA, and SJA), fucose (UEA-I) and complex type N-glycan (PHA-E and PHA-L) groups. The free border of the VSE was positive for all 21 lectins, and 18 of the lectins (excluding DBA, SJA, and PHA-L) showed weak and/or moderate staining in the receptor cells. The supporting cells were weakly positive for 19 lectins (excluding PNA and SJA). Moreover, 17 lectins (excluding BSL-II, Jacalin, PNA, and SJA) were expressed in the basal cells. In the VNSE of roe deer, the free border showed staining for all 21 lectins examined. The ciliated cells were positive for 16 lectins (excluding BSL-II, DSL, PNA, VVA, and SJA). Furthermore, 15 lectins (excluding DSL, LEL, ECL, UEA-I, PHA-E, and PHA-L) were expressed in goblet cells. Twenty lectins (excluding SJA) were expressed in the acini of the vomeronasal glands. Collectively, both VSE and VNSE were rich in N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, fucose, and complex-type N-glycans, although the different cell types of the VSE and VNSE expressed different glycoconjugates of varying intensities, suggesting that these carbohydrate residues may be involved in odor perception as well as cell-to-cell communication in the VNO.

Immunohistochemical study of arginases 1 and 2 in the olfactory bulbs of the Korean roe deer, Capreolus pygargus

Arginases are enzymes of the urea cycle that catalyze the hydrolysis of l-arginine to ornithine and urea. The enzymes are core components of the arginine-ornithine-glutamate-γ-amino butyric acid pathway of the central nervous system. In the present study, we immunohistochemically determined the localization of arginase 1 and 2 in the olfactory bulb (OB) of the roe dear (Capreolus pygargus). Reverse transcription PCR revealed that the mRNAs encoding both arginase 1 and 2 were expressed in the OB. Arginase 1 was localized to olfactory nerve axons, calcitonin gene-related peptide-positive mitral/tufted cells (excitatory neurons), and glutamate acid decarboxylase 65/67-immunopositive periglomerular cells of the main olfactory bulb. The arginase 2 immunoreactivities in the OB tissues were similar to those of arginase 1. Furthermore, both arginases were detected in the accessory olfactory bulb. These findings suggest that both arginase 1 and 2 are potentially associated with excitatory and inhibitory neurotransmitter activities in animal OBs, including those of the roe deer.

Lectin histochemistry of Kudoa septempunctata genotype ST3-infected muscle of olive flounder (Paralichthys olivaceus)

The localization of carbohydrate terminals in Kudoa septempunctata ST3-infected muscle of olive flounder (Paralichthys olivaceus) was investigated using lectin histochemistry to determine the types of carbohydrate sugar residues expressed in Kudoa spores. Twenty-one lectins were examined, i.e., N-acetylglucosamine (s-WGA, WGA, DSL-II, DSL, LEL, STL), mannose (Con A, LCA, PSA), galactose/N-acetylgalactosamine (RCA12, BSL-I, VVA, DBA, SBA, SJA, Jacalin, PNA, ECL), complex type N-glycans (PHA-E and PHA-L), and fucose (UEA-I). Spores encased by a plasmodial membrane were labeled for the majority of these lectins, with the exception of LCA, PSA, PNA, and PHA-L. Four lectins (RCA 120, BSL-I, DBA, and SJA) belonging to the galactose/N-acetylgalactosamine group, only labeled spores, but not the plasmodial membrane. This is the first confirmation that various sugar residues are present in spores and plasmodial membranes of K. septempunctata ST3.

Histochemical study of the olfactory mucosae of the horse

The olfactory mucosae of the horse were examined by using histology and lectin histochemistry to characterize the carbohydrate sugar residues therein. Histological findings revealed that olfactory epithelium (OE) consisted of both olfactory marker protein (OMP)- and protein gene product (PGP) 9.5-positive receptor cells, supporting cells and basal cells with intervening secretory ducts from Bowman's glands. Mucus histochemistry showed that Bowman's gland acini contain periodic acid-Schiff (PAS) reagent-positive neutral mucins and alcian blue pH 2.5-positive mucosubstances. Lectin histochemistry revealed that a variety of carbohydrate sugar residues, including N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, fucose and complex type N-glycan groups, are present in the various cell types in the olfactory mucosa at varying levels. Collectively, this is the first descriptive study of horse olfactory mucosa to characterize carbohydrate sugar residues in the OE and Bowman's glands.

Immunohistochemical localization of GABAergic key molecules in the main olfactory bulb of the Korean roe deer, Capreolus pygargus

Gamma-amino butyric acid (GABA) negatively regulates the excitatory activity of neurons and is a predominant neurotransmitter in the nervous system. The olfactory bulb, the main center in the olfactory system, is modulated by inhibitory interneurons that use GABA as their main neurotransmitter. The present study aimed to evaluate GABAergic transmission in the main olfactory bulb (MOB) of the Korean roe deer (Capreolus pygargus) by examining the immunohistochemical localization of GABAergic key molecules, including glutamic acid decarboxylase (GAD), vesicular GABA transporter (VGAT), GABA transporters (GATs; GAT-1 and GAT-3), and potassium sodium chloride co-transporter 2 (KCC2). GAD, VGAT, and KCC2 were expressed in the glomerular layer (GL), external plexiform layer (ePL), mitral cell layer (ML), and granule cell layer (GrL). Intense GAT-1 expression was observed in the GL; GAT-1 expression was discernible in the ePL, ML, and GrL. However, intense GAT-3 expression was extensively observed in all layers of the MOB. These results suggest that substantial GABAergic synapses are present in the GL, ePL, ML, and GrL. Furthermore, the released GABA may be removed by GAT-1 and GAT-3 in the GL, and the majority of GABA, which is present in the ePL to GrL, may undergo reuptake by GAT-3. This is the first morphological and descriptive study of GABAergic transmission in the MOB of Korean roe deer.