Immunohistochemical studies for the neuronal elements in the vomeronasal organ of the one-humped camel

Histological evaluation of the alpaca (Vicugna pacos) vomeronasal organ

Little is known about the neuronal structure of the vomeronasal organ (VNO), a receptor organ responsible for pheromone perception, in the alpaca (Vicugna pacos). This study was performed to determine the localization of neuronal elements, including protein gene product 9.5 (PGP 9.5), a pan-neuronal marker, olfactory marker protein (OMP), a marker of mature olfactory receptor cells, and phospholipase C beta 2 (PLC-β2), a marker of solitary chemoreceptor cells (SCCs), in the VNO. OMP was identified in receptor cells of the vomeronasal sensory epithelium (VSE), while PGP 9.5 and PLC-β2 were localized in both the VSE and vomeronasal non-sensory epithelium. Collectively, these results suggested that the alpaca VNO possesses SCCs and olfactory receptor cells, which recognize both harmful substances and pheromones.

Lectin histochemistry of the olfactory mucosa of Korean native cattle, Bos taurus coreanae

BACKGROUND

The olfactory mucosa (OM) is crucial for odorant perception in the main olfactory system. The terminal carbohydrates of glycoconjugates influence chemoreception in the olfactory epithelium (OE).

OBJECTIVES

The histological characteristics and glycoconjugate composition of the OM of Korean native cattle (Hanwoo, Bos taurus coreae) were examined to characterize their morphology and possible functions during postnatal development.

METHODS

The OM of neonate and adult Korean native cattle was evaluated using histological, immunohistochemical, and lectin histochemical methods.

RESULTS

Histologically, the OM in both neonates and adults consists of the olfactory epithelium and the lamina propria. Additionally, using periodic acid Schiff and Alcian blue (pH 2.5), the mucus specificity of the Bowman's gland duct and acini in the lamina propria was determined. Immunohistochemistry demonstrated that mature and immature olfactory sensory neurons of OEs express the olfactory marker protein and growth associated protein-43, respectively. Lectin histochemistry indicated that numerous glycoconjugates, including as N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, complex type N-glycan, and fucose groups, were expressed at varied levels in the different cell types in the OMs of neonates and adults at varying levels. According to our observations, the cattle possessed a well-developed olfactory system, and the expression patterns of glycoconjugates in neonatal and adult OMs varied considerably.

CONCLUSIONS

This is the first study to describe the morphological assessment of the OM of Korean native cattle with a focus on lectin histochemistry. The findings suggest that glycoconjugates may play a role in olfactory chemoreception, and that their labeling properties may be closely related to OM development and maturity.

Immunolocalization of Receptor and Chemoreceptor Modules in the Sheep Vomeronasal Organ

The vomeronasal organ (VNO) is the peripheral receptor organ of the accessory olfactory system, which is responsible for both sexual and innate behaviors. The degree of neuronal differentiation and maturation of the vomeronasal receptor cells together with the verification of the presence of the solitary chemoreceptor cells (SCCs) in the VNO of Corriedale sheep were assessed using immunofluorescence. A protein gene product 9.5 (PGP 9.5), which is a neuronal marker recognized to be expressed in most neurons of vertebrate species, an olfactory marker protein (OMP) that is precise for mature olfactory receptor cells, and lastly phospholipase C-β2 (PLC-β2), a marker in the signal transduction pathway of SCCs, were all tested. The cell bodies and dendrites of almost all receptor cells in the sensory epithelium were strongly positive for PGP 9.5 and to a lesser extent for OMP. In the nonsensory wall, all cells were negative for both PGP 9.5 and OMP; however, some positive PGP 9.5 immunoreactive fibers were identified. For PLC-β2, only 1 basally situated SCC could be identified in the sensory epithelium. A higher number was demonstrated in the nonsensory wall. Corriedale sheep possess matured, fully differentiated vomeronasal receptor cells in their sensory wall, suggesting an appropriate pheromone perception. Additionally, the VNO in sheep may participate in the usual transduction mechanisms, though it is seemingly not a chemoreceptor organ.

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.

Histological features of the vomeronasal organ in the giraffe, Giraffa camelopardalis

The vomeronasal organ (VNO) that preferentially detects species-specific substances is diverse among animal species, and its morphological properties seem to reflect the ecological features of animals. This histological study of two female reticulated giraffes (Giraffa camelopardalis reticulata) found that the VNO is developed in giraffes. The lateral and medial regions of the vomeronasal lumen were covered with sensory and nonsensory epithelia, respectively. The vomeronasal glands were positive for periodic acid-Schiff and alcian blue (pH 2.5) stains. The VNO comprises several large veins like others in the order Cetartiodactyla, suggesting that these veins function in a pumping mechanism in this order. In addition, numerous thin-walled vessels located immediately beneath the epithelia covering the lumen entirely surrounded the vomeronasal lumen. This sponge-like structure might function as a specific secondary pump in giraffes.

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.

Morphological study on the olfactory systems of the snapping turtle, Chelydra serpentina

In this study, the olfactory system of a semi-aquatic turtle, the snapping turtle, has been morphologically investigated by electron microscopy, immunohistochemistry, and lectin histochemistry. The nasal cavity of snapping turtle was divided into the upper and lower chambers, lined by the sensory epithelium containing ciliated and non-ciliated olfactory receptor neurons, respectively. Each neuron expressed both Gαolf, the α-subunit of G-proteins coupling to the odorant receptors, and Gαo, the α-subunit of G-proteins coupling to the type 2 vomeronasal receptors. The axons originating from the upper chamber epithelium projected to the ventral part of the olfactory bulb, while those from the lower chamber epithelium to the dorsal part of the olfactory bulb. Despite the identical expression of G-protein α-subunits in the olfactory receptor neurons, these two projections were clearly distinguished from each other by the differential expression of glycoconjugates. In conclusion, these data indicate the presence of two types of olfactory systems in the snapping turtle. Topographic arrangement of the upper and lower chambers and lack of the associated glands in the lower chamber epithelium suggest their possible involvement in the detection of odorants: upper chamber epithelium in the air and the lower chamber epithelium in the water.

Immunohistochemical and lectin histochemical studies on the developing olfactory organs of fetal camel

Little is known about the development of the olfactory organs of camel. In this study, prenatal development and neuronal differentiation of the vomeronasal organ (VNO) and the olfactory epithelium (OE) of the one-humped camel were studied by immunohistochemistry and lectin histochemistry. A neuronal marker, protein gene product (PGP) 9.5, but not a marker of fully differentiated olfactory receptor cells, olfactory marker protein, intensely labeled the olfactory receptor cells of the VNO and OE at 395 mm, 510 mm, and 530 mm fetal ages, indicating that the olfactory receptor cells are differentiated, but not fully matured both in the VNO and the OE. In 187 mm and 190 mm fetuses, PGP 9.5 yielded faint immunoreactive signals in the VNO, but not in the OE, although the presence of olfactory receptor cells were demonstrated in both tissues by intense WGA and LEL stainings. We conclude that the camel VNO and OE bear differentiated, but still immature receptor cells; in addition, the onset of neuronal differentiation seems to be somewhat earlier in the VNO than in the OE till half of the prenatal life.