Immunolocalization of VEGF/VEGFR system in human fetal vomeronasal organ during early development

The vomeronasal system (VNS) is an accessory olfactory structure present in most mammals adhibited to the detection of specific chemosignals implied in social and reproductive behavior. The VNS comprises the vomeronasal organ (VNO), vomeronasal nerve and accessory olfactory bulb. VNO is characterized by a neuroepithelium constituted by bipolar neurons and supporting and stem/progenitor cells. In humans, VNO is present during fetal life and is supposed to possess chemoreceptor activity and participate in gonadotropin-releasing hormone neuronal precursor migration toward the hypothalamus. Instead, the existence and functions of VNO in postnatal life is debated. Vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) have been demonstrated to play fundamental roles in various neurogenic events. However, there are no data regarding the localization and possible function of VEGF/VEGFRs in human fetal VNO. Therefore, this study was conceived to investigate the expression of VEGF/VEGFRs in human VNO in an early developmental period (9–12 weeks of gestation), when this organ appears well structured. Coronal sections of maxillofacial specimens were subjected to peroxidase-based immunohistochemistry for VEGF, VEGFR-1 and VEGFR-2. Double immunofluorescence for VEGF, VEGFR-1 or VEGFR-2 and the neuronal marker protein gene product 9.5 (PGP 9.5) was also performed. VEGF expression was evident in the entire VNO epithelium, with particularly strong reactivity in the middle layer. Strongly VEGF-immunostained cells with aspect similar to bipolar neurons and/or their presumable precursors were detected in the middle and basal layers. Cells detaching from the basal epithelial layer and detached cell groups in the surrounding lamina propria showed moderate/strong VEGF expression. The strongest VEGFR-1 and VEGFR-2 expression was detected in the apical epithelial layer. Cells with aspect similar to bipolar neurons and/or their presumable precursors located in the middle and basal layers and the detaching/detached cells displayed a VEGFR-1 and VEGFR-2 reactivity similar to that of VEGF. The basal epithelial layer exhibited stronger staining for VEGFRs than for VEGF. Cells with morphology and VEGF/VEGFR expression similar to those of the detaching/detached cells were also detected in the middle and basal VNO epithelial layers. Double immunofluorescence using anti-PGP 9.5 antibodies demonstrated that most of the VEGF/VEGFR-immunoreactive cells were neuronal cells. Collectively, our findings suggest that during early fetal development the VEGF/VEGFR system might be involved in the presumptive VNO chemoreceptor activity and neuronal precursor migration.     

Morphological characteristics of the vomeronasal organ of the newborn Asian elephant (Elephas maximus)

The 6-week-old Asian elephant (Elephas maximus) has a well-documented precocious flehmen response to pheromones, suggesting that the pheromone-detecting vomeronasal organ (VNO) is functional very early in the life of this species. To further document this, the VNOs of two newborn elephants were examined in situ and analyzed by light microscopy (LM) to ascertain their structural maturity at birth. A tubular, cartilage-encased VNO was located along the anterior base of each side of the nasal septum. Its rostral end was connected to a duct to the roof of the mouth; the caudal end was attached to a well-defined vomeronasal nerve projecting toward the brain. LM revealed distinctive differences in the mucosae bordering the horseshoe-shaped lumen: a concave, sensory mucosa, and a convex, nonsensory mucosa. Small groups of receptor neurons were observed among ciliated columnar cells in the sensory epithelium. Numerous unmyelinated nerve bundles and blood vessels filled the underlying lamina propria (LP) and a small section of the vomeronasal nerve was conspicuous at one edge. The nonsensory mucosa manifested a thinner epithelium that principally consisted of ciliated columnar cells, some of which showed a granular cytoplasm, and a conspicuous row of basal cells. The LP was replete with acinar glands and ducts that opened into the lumen. This study shows that the VNO of the newborn elephant has reached an advanced stage of structural maturity, closely resembling that of the adult. Its composition supports the view that flehmen at 6 weeks delivers pheromones to a functional VNO.     

Observations on the vomeronasal organ of prenatal Tarsius bancanus borneanus with implications for ancestral morphology

Adult primates have at least five known phenotypes of vomeronasal organ (VNO), ranging from the typical morphology seen in most other mammals to complete absence. With such morphological disparity, the phylogenetic value and any inferences on ancestral VNO morphology of the primate VNO are left uncertain. The present study investigated the VNO of embryonic and fetal Tarsius bancanus borneanus (n = 4) in comparison with prenatal specimens from four other species of primates in an effort to clarify adult morphological variations. In all except one of the fetal primates, the VNO communicated to the nasopalatine duct. One exception occurred in the largest fetal Tarsius (25 mm crown-rump length), in which the VNO communicated with the nasal cavity alone. The vomeronasal neuroepithelium was well differentiated from a thinner, non-sensory epithelium in all Tarsius and New World monkeys studied, as well as late embryonic and fetal Microcebus myoxinus. In anterior sections, this neuroepithelium was found in a more superior location in Tarsius and New World monkeys compared with Microcebus myoxinus. In all primates, masses of cell bodies were found superior to the VNO, intermingled with nerve fibres. These morphologically resembled luteinizing hormone-releasing hormone neurons described in other mammals, including humans, suggesting that a primitive association of these neurons with the VNO may exist in all primate taxa. The present study revealed that prenatal similarities exist in Tarsius and New World primates in VNO epithelial morphology. However, these are transient stages of morphology. If tarsiers and anthropoids do represent a clade (Haplorhini), then the atypical morphology seen in adult tarsiers and New World monkeys probably represents the adult VNO morphology of a haplorhine common ancestor.     

Galectin-3 immunohistochemistry in the vomeronasal organ of the domestic pig, Sus scrofa

The immunohistochemical localization of galectin-3, a β-galactoside-binding protein, was studied in the vomeronasal organ (VNO) of fetal, 1-day-old, and 6-month-old pigs.In all age groups, the porcine VNO consisted of vomeronasal sensory epithelium (VSE) located medially and non-sensory vomeronasal respiratory epithelium (VRE) located laterally. In the pig, the VNO epithelium increased in height with postnatal development from fetus to adult. In the VSE of all stages examined, galectin-3 immunostaining was seen in the supporting cells and free border, but not in receptor or basal cells. Galectin-3 immunostaining was seen in all layers of the VRE, and the intensity increased with postnatal development. In the lamina propria, galectin-3 was detected in some ductal epithelial cells and the vomeronasal nerve sheath, but not in the acini of the Jacobson glands in all age groups. In view of these observations, we postulate that galectin-3 plays a role in cell survival and cell adhesion in both the VSE and VRE of porcine VNO in all age groups.     

Morphological and histological features of the vomeronasal organ in the brown bear

The vomeronasal organ (VNO) is a peripheral receptor structure that is involved in reproductive behavior and is part of the vomeronasal system. Male bears exhibit flehmen behavior that is regarded as the uptake of pheromones into the VNO to detect estrus in females. However, the morphological and histological features of the VNO in bears have not been comprehensively studied. The present study investigated the properties and degree of development of the VNO of the brown bear by histological, histochemical and ultrastructural methods. The VNO of bears was located at the same position as that of many other mammals, and it opened to the mouth like the VNO of most carnivores. The shape of the vomeronasal cartilages and the histological features of the sensory epithelium in the bear VNO were essentially similar to those of dogs. Receptor cells in the VNO of the bear possessed both cilia and microvilli like those of dogs. The dendritic knobs of receptor cells were positive for anti‐G protein alpha‐i2 subunit (G_αi2) but negative for anti‐G protein alpha‐o subunit_, indicating preferential use of the V1R‐G_αi2 pathway in the vomeronasal system of bears, as in other carnivores. The VNO of the bear possessed three types of secretory cells (secretory cells of the vomeronasal gland, multicellular intraepithelial gland cells and goblet cells), and the present findings showed that the secretory granules in these cells also had various properties. The vomeronasal lumen at the middle region of the VNO invaginated toward the ventral region, and this invagination contained tightly packed multicellular intraepithelial gland cells. To our knowledge, this invagination and intraepithelial gland masses in the VNO are unique features of brown bears. The VNO in the brown bear, especially the secretory system, is morphologically well‐developed, suggesting that this organ is significant for information transmission in this species.     

Ontogenetic observations on the vomeronasal organ in two species of tamarins using neuron-specific beta-tubulin III

Callitrichid primates (tamarins, marmosets) have extreme variation in the vomeronasal organ (VNO), including ontogenetic differences in the neuroepithelium and vomeronasal duct (VND) patency at birth. Such differences render the timing and extent of VNO maturation debatable in callitrichids, but no studies have used neuron-specific immunohistochemical markers to address this question. The present study compared the number of VNO epithelial cells that express immunoreactivity to neuron-specific beta-tubulin III (BT), VNO length, and VNO cross-sectional area between two species of tamarins (Leontopithecus rosalia and Saguinus geoffroyi) that differed in perinatal VND patency. Neonatal lemurs and adult marmosets and bushbabies were also examined for a comparison to species previously shown to have a relatively large amount of VNO neuroepithelium and patent VNDs. The head of each specimen was serially sectioned in the coronal plane. Based on known rostrocaudal start/stop points of the VNO, selected unstained sections were used for BT protocols and area measurement at three percentiles (25th, 50th, 75th) in each specimen. Each section was photographed and enlarged for cell counts and measurement of cross-sectional epithelial area. In each specimen, the number of BT(+) cells in the VNO was counted at each percentile and expressed as a number per mm(2). Results indicated that lemur VNOs had a dense population of BT(+) cells at birth, but the VNO was more varied in the tamarin species. S. geoffroyi had few or no BT(+) cells in VNOs of neonates, which had fused VNDs, but had an increased BT(+) population by 1 and 2 months postnatal age, when the VND was patent. Of the species with patent VNDs at birth, neonatal L. rosalia had a denser population of BT(+) cells compared to S. geoffroyi, though not to the degree seen in neonatal lemurs or adult marmosets and bushbabies. These findings show that BT immunohistochemistry is a useful comparative method for the study of VNOs in subadult primates. Since the quantity of nonsensory VNO epithelium varies substantially between species, epithelial area measurements may be misleading, and BT(+) cell counts appeared to be the best quantitative method for comparing receptor neuron numbers among primates. It is suggested that the greater BT(+) cell population in L. rosalia at all subadult stages examined reveals an earlier maturation of the neuroepithelium compared to S. geoffroyi. Further investigation should consider whether this may relate to a comparatively brief subadult ontogeny and early onset of adult behaviors in L. rosalia compared to other tamarins studied to date.     

Protein gene-product 9.5 in developing mouse circumvallate papilla: comparison with neuron-specific enolase and calcitonin gene-related peptide

The present study was made to investigate the ontogeny of protein gene-product 9.5 (PGP 9.5)-like immunoreactivity (-LI) in the developing mouse circumvallate papilla (CVP), and its distribution was compared to that of neuron-specific enolase (NSE) and calcitonin gene-related peptide (CGRP). In adult CVP, PGP 9.5-LI was observed in the subgemmal nerve plexus; some thin PGP 9.5-like immunoreactive (-IR) nerve fibers penetrated taste buds and apical epithelium. PGP 9.5-LI was also observed in the spindle-shaped cells in taste buds, and a small number of round- or oval-shaped ganglionic cells in the lamina propria. The distribution of NSE-LI was comparable to that of PGP 9.5-LI. CGRP-LI was observed in the nerve fibers only; distribution of CGRP-IR nerve fibers was similar to that of PGP 9.5-IR nerve fibers, although the number of CGRP-IR nerve fibers was smaller than that of PGP 9.5-IR nerve fibers. At least six developmental stages were defined with regard to the developmental changes in the distribution of PGP 9.5-LI from embryonic day (E) 12 to adulthood: Stage I (E12–13) — a dense nerve plexus of PGP 9.5-IR nerve fibers was detected in the lamina propria beneath the core of newly-formed papilla. Stage II (E14–16) — thin PGP 9.5-IR nerve fibers penetrated the apical epithelium, and a few round-shaped cells in the apical epithelium also displayed PGP 9.5-LI. Stage III (E17–18) — thin PGP 9.5-IR nerve fibers penetrated the inner lateral epithelium of the trench. Stage IV [Postnatal day (P) 0–3] many PGP 9.5-IR nerve fibers penetrated the outer lateral epithelium of the trench; later in this stage, taste buds appeared. Stage V (P5–10) — a small number of PGP 9.5 IR cells in the taste buds appeared, and their number increased gradually. Stage VI (PI4-adult) — the number of PGP 9.5-IR taste cells increased and reached the adult level, while the number of PGP 9.5-IR nerve fibers decreased. The development of NSE-LI was similar to that of PGP 9.5-LI. CGRP-IR nerve fibers were detected at E12 in the lamina propria, and the development of the intraepithelial CGRP-IR nerve fibers was similar to that of PGP 9.5-IR nerve fibers. The present results indicate that invasion by nerve fibers of the epithelium of lingual papillae occurs in a complex manner, and that these nerve fibers may participate in the formation of the taste buds.     

Ion conductances in supporting cells isolated from the mouse vomeronasal organ

The vomeronasal organ (VNO) is a chemosensory structure involved in the detection of pheromones in most mammals. The VNO sensory epithelium contains both neurons and supporting cells. Data suggest that vomeronasal neurons represent the pheromonal transduction sites, whereas scarce information is available on the functional properties of supporting cells. To begin to understand their role in VNO physiology, we have characterized with patch-clamp recording techniques the electrophysiological properties of supporting cells isolated from the neuroepithelium of the mouse VNO. Supporting cells were distinguished from neurons by their typical morphology and by the lack of immunoreactivity for Ggamma8 and OMP, two specific markers for vomeronasal neurons. Unlike glial cells in other tissues, VNO supporting cells exhibited a depolarized resting potential (about -29 mV). A Goldman-Hodgkin-Katz analysis for resting ion permeabilities revealed indeed an unique ratio of P(K):P(Na):P(Cl) = 1:0.23:1.4. Supporting cells also possessed voltage-dependent K(+) and Na(+) conductances that differed significantly in their biophysical and pharmacological properties from those expressed by VNO neurons. Thus glial membranes in the VNO can sustain significant fluxes of K(+) and Na(+), as well as Cl(-). This functional property might allow supporting cells to mop-up and redistribute the excess of KCl and NaCl that often occurs in certain pheromone-delivering fluids, like urine, and that could blunt the sensitivity of VNO neurons to pheromones. Therefore vomeronasal supporting cells could affect chemosensory transduction in the VNO by regulating the ionic strength of the pheromone-containing medium.     

Development of substance P immunoreactivity in the mouse vomeronasal organ

We investigated the development of substance P immunoreactivity in mouse vomeronasal organs in embryos, juveniles, and adults. In all stages, substance P fibers were found in the receptor-free epithelial area, but never in the neuroepithelium. Substance P fibers were found sparsely in the lamina propria of 15-day-old embryos. Although buds of the vomeronasal glands in the cavernous tissue were observed in 17-day-old embryos, and gradually grew in size and numbers, the substance P fibers around them decreased after about the 13th day. Thus, substance P may be a trophic factor for the development of the vomeronasal glands in the cavernous tissue. We first recognized substance P fibers reaching the surface of the receptor-free epithelium in 13-day-old pups. In 21-day-old mice, substance P fibers were as well developed as in adult mice. Considering the development of the substance P fibers in the receptor-free epithelium and the cavernous tissue, they probably cause the vasodilation of the cavernous tissue via local axon reflexes. These structures may then act as a defense system, eliminating noxious stimulus substances sucked into the vomeronasal organ.     

Immunohistochemistry of the canine vomeronasal organ

The canine's olfactory acuity is legendary, but neither its main olfactory system nor its vomeronasal system has been described in much detail. We used immunohistochemistry on paraffin-embedded sections of male and female adult dog vomeronasal organ (VNO) to characterize the expression of proteins known to be expressed in the VNO of several other mammals. Basal cell bodies were more apparent in each section than in rodent VNO and expressed immunoreactivity to anticytokeratin and antiepidermal growth factor receptor antibodies. The thin layer of neurone cell bodies in the sensory epithelium and axon fascicles in the lamina propria expressed immunoreactivity to neurone cell adhesion molecule, neurone-specific beta tubulin and protein gene product 9.5. Some neurones expressed growth-associated protein 43 (GAP43): and a number of those also expressed neurone-specific beta tubulin-immunoreactivity. Some axon fascicles were double labelled for those two proteins. The G-protein alpha subunits Gi and Go, involved in the signal transduction pathway, showed immunoreactivity in the sensory cell layer. Our results demonstrate that the canine vomeronasal organ contains a population of cells that expresses several neuronal markers. Furthermore, GAP43 immunoreactivity suggests that the sensory epithelium is neurogenic in adult dogs.     

Immunohistochemistry of the canine vomeronasal organ

The canine's olfactory acuity is legendary, but neither its main olfactory system nor its vomeronasal system has been described in much detail. We used immunohistochemistry on paraffin-embedded sections of male and female adult dog vomeronasal organ (VNO) to characterize the expression of proteins known to be expressed in the VNO of several other mammals. Basal cell bodies were more apparent in each section than in rodent VNO and expressed immunoreactivity to anticytokeratin and antiepidermal growth factor receptor antibodies. The thin layer of neurone cell bodies in the sensory epithelium and axon fascicles in the lamina propria expressed immunoreactivity to neurone cell adhesion molecule, neurone-specific beta tubulin and protein gene product 9.5. Some neurones expressed growth-associated protein 43 (GAP43): and a number of those also expressed neurone-specific beta tubulin-immunoreactivity. Some axon fascicles were double labelled for those two proteins. The G-protein alpha subunits Gi and Go, involved in the signal transduction pathway, showed immunoreactivity in the sensory cell layer. Our results demonstrate that the canine vomeronasal organ contains a population of cells that expresses several neuronal markers. Furthermore, GAP43 immunoreactivity suggests that the sensory epithelium is neurogenic in adult dogs.     

A morphological study of the vomeronasal organ and the accessory olfactory bulb in the Korean roe deer, Capreolus pygargus

The vomeronasal organ (VNO) and accessory olfactory bulb (AOB) of the Korean roe deer (Capreolus pygargus) were studied histologically to evaluate their morphological characteristics. Grossly, the VNO, encased by cartilage, has a paired tubular structure with a caudal blind end and a rostral connection through incisive ducts on the hard palate. In the VNO, the vomeronasal sensory epithelium (VSE) consists of galectin-3-positive supporting cells, protein gene product (PGP) 9.5-positive receptor cells, and basal cells. The vomeronasal respiratory epithelium (VRE) consists of a pseudostratified epithelium. The AOB strata included a vomeronasal nerve layer (VNL), a glomerular layer (GL), a mitral/tufted cell layer, and a granular cell layer. All lectins used in this study, including Bandeiraea simplicifolia agglutinin isolectin B4 (BSI-B4), soybean agglutinin (SBA), Ulex europaeus agglutinin I (UEA-I), and Triticum vulgaris wheat germ agglutinin (WGA), labeled the VSE with varying intensity. In the AOB, both the VNL and the GL reacted with BSI-B4, SBA, and WGA with varying intensity, but not with UEA-I. This is the first morphological study of the VNO and AOB of the Korean roe deer, which are similar to those of goats.     

Three-dimensional scanning electron microscopic study of the normal hamster olfactory epithelium

Summary The olfactory epithelium of the adult hamster (Mesocricetus auratus) was studied using the scanning electron microscope. A method that produced fractures in the epithelium exposed structures below the surface and made it possible to examine the morphological and structural relationships among cells.Three cell types were studied: supporting cells, olfactory neurons (receptor cells) and basal cells. Supporting cells were observed spanning the full extent of the epithelium, and had basal foot processes that terminated at or near the basal lamina. Along the lateral margin of supporting cells, cellular processes were observed extending outwards, reaching olfactory neurons and adjacent supporting cells. These cellular contacts among supporting cells and olfactory neurons were present at different levels of the epithelium. Olfactory neurons were located primarily in the middle and lower epithelial regions. Their dendritic processes reached the epithelial surface in a straight or tortuous manner, passing between the supporting cells. Olfactory axons were observed as thin unbranched processes that emerged from a conical hillock region, passed basally, and fasciculated into larger sensory bundles within the lamina propria. Basal cells were observed adjacent to the basal lamina as a row of single cells or clustered in groups. Within the lamina propria connective tissue, blood vessels, axon bundles and Bowman's glands were examined. Bowman's glands were composed of pyramidal secretory cells arranged about a single duct that extended to the epithelial surface.Scanning electron microscopy provided a unique three-dimensional analysis of cell structure within the olfactory epithelium. The results provide new and different observations on the detailed morphology and intimate relationships that exist among epithelial cells, and complement previous light and transmission EM observations.     

Light Microscopic and Ultrastructural Observations on the Vomeronasal Organ of Anoura (Chiroptera: Phyllostomidae)

The vomeronasal organ (VNO) is known to be present in bats of the family Phyllostomidae, but in most species this is inferred from the presence of accessory olfactory bulbs. Like primates, bats have profound intergroup variations in the vomeronasal system. Of the family Phyllostomidae (49 genera, 143 species) the VNO of approximately 60 species has been studied. Here, we report light microscopic observations of the VNO of Anoura geoffroyi (fetus and adult), A. caudifer, and A. cultrata, as well as ultrastructural observations of the VNO in adult A. geoffroyi. The organ is crescent‐shaped, with a wide lumen encroached by a “mushroom body” that contains a venous sinus. In adults, the vomeronasal cartilage is reduced, being longer in absolute length in fetal A. geoffroyi compared with the adult. In the neuroepithelium, the receptor cell microvilli are dark, distinct, and short, emerging from a vesicular tuft; the supporting cell microvilli are relatively much longer. Large paravomeronasal ganglia are observed. The receptor‐free epithelium is undulating and lacks cilia or microvilli. Some characteristics of the VNO in Anoura have not been reported in other chiropterans to date, such as the marked reduction of the vomeronasal cartilage and absence of cilia in the receptor‐free epithelium. Moreover, if A. geoffroyi is representative, the genus has an adult neuroepithelial volume similar to other mammals of its body size. Further examination of uninvestigated phyllostomid VNOs may elucidate a phylogenetic history of the family, as well as ecological or social correlates of the VNO in the order Chiroptera. Anat Rec 290:1341–1354, 2007. © 2007 Wiley‐Liss, Inc.     

The human vomeronasal organ. Part II: prenatal development

During the 20th century, the human vomeronasal organ (VNO) has been controversial regarding its structure, function, and even identity. Despite reports that provide evidence for its presence throughout prenatal and postnatal ontogeny, some studies and numerous textbooks declare its absence in late fetal and postnatal humans. To that end, the present study was designed to establish firmly whether the human VNO is homologous with that of other mammals and whether it degenerates (partially or completely) or persists throughout prenatal development. Fifty human embryos and fetuses (33 d to 32 wk fertilisation age) and 2 neonates were examined by light microscopy. Four embryonic primates (mouse lemurs) were examined for a comparison of VNO embryogenesis. The presence or absence and structural characteristics of the VNO and supporting tissues are described. The first appearance of the VNO was in the form of bilateral epithelial thickenings of the nasal septum, the vomeronasal primordium. The primordia invaginated between 37 and 43 d of age and formed the tubular VNO. The tubular VNO was located dorsally at a variable distance from, but was always spatially separated from the paraseptal cartilages. The mouse lemurs examined in this study and other reports from the literature indicate that the human VNO resembles that of primates having functional VNOs until just after a tubular VNO is formed. Examination of the VNO and adjacent tissues suggested that the VNO may lose receptor cells and corresponding vomeronasal nerves and become a ciliated, pseudostratified epithelium between ～ 12 and 14 wk of age. Our findings indicate the prenatal human VNO goes through 3 successive stages: early morphogenesis, transformation (of the epithelium), and growth. These observations indicated that (1) all embryonic humans develop a vomeronasal organ which is homologous with the VNOs of other mammals, but which has become displaced and highly variable in relative location during embryogenesis; (2) the human vomeronasal organ does not degenerate prenatally, but very likely loses the functional components of the vomeronasal complex of other mammals; and (3) the remnant of the human VNO persists until birth and beyond.     

Evaluation of PGP9.5 in the diagnosis of Hirschsprung's disease.

The ability of an acetylcholinesterase-stained frozen section to detect an increase in large cholinergic nerve fibres within the muscularis mucosae and extending into the lamina propria was a significant step forward in the diagnosis of Hirschsprung's disease (HD). However, such frozen section diagnosis is not always possible. The purpose of this study was to assess the ability of PGP9.5 to detect this pattern of mucosal nerve fibre staining immunohistochemically. Sixty-four specimens were included in the study. Twenty-six of these had been diagnosed as HD by conventional means. All cases were stained immunohistochemically with PGP9.5, S100, and anti-neurofilaments (NF). Twenty-four cases of HD were also stained with neurone-specific enolase (NSE). PGP9.5 reliably stained fibres in the mucosal and submucosal plexuses, and ganglion cells, when the latter were present. This positive staining of ganglion cells was more intense than that seen with NSE, and the positive fibre staining was more intense than that seen with NF. Increased lamina propria fibres were detected with PGP9.5 in only 37 per cent of HD cases compared with S100 positive staining in 60 per cent of cases. However, when S100 staining was assessed alone, it gave a higher false-negative rate in diagnosing HD than PGP9.5 used alone. Therefore we would recommend the use of PGP9.5 and S100 together for the immunohistochemical diagnosis of HD in formalin-fixed biopsies.     

An ultrastructural study of glomeruli associated with vomeronasal organs transplanted into the rat CNS

Rat neonate vomeronasal organs were transplanted into the parietal cortex of littermates to examine their survival and the behavior of axon growth into the surrounding host brain parenchyma. After survival times of 10–100 days the brains were processed for ultrastructural examination. The transplanted vomeronasal organs (VNO) formed several vesicles lined with a sensory epithelium. From these sensory epithelia, VNO neurons leave the epithelium and enter the host brain. Transplant neurons grew axons that fasciculated into bundles surrounded by sheath cell processes and formed one or more fiber plexuses containing distinct globose or spherical-shaped glomeralar-like structures. The glomeruli consisted of nerve terminals between which existed asymmetric synaptic contacts. Rarely did we observe clear reciprocal synapses. The glomeruli also contained terminals that showed signs of degeneration, such as increased density of the terminals, clumping of mitochondria and multivesicular bodies. The glomeruli were not partitioned or subdivided by glial septa; however, glial profiles were interspersed among the sensory terminals. Transplant glomeruli also lacked periglomerular cells and had no definitive glial envelope. These results suggest that glomerular formation is not dependent on dendrite contribution of second order neurons or glial support, but rather on a complementary population of receptor neurons.     

Vascularization of developing human olfactory neuroepithelium - a morphometric study

The present study reveals intraepithelial capillaries in the olfactory neuroepithelium of human fetuses aged between 12 and 24 weeks of gestation, which disappear at birth. The area occupied by the intraepithelial capillaries increases significantly with fetal age (0.047 +/- 0.014 microm(2)/microm(2) at 12 weeks and 0.101 +/- 0. 025 microm(2)/microm(2) at 24 weeks) and with the thickness of the epithelium (45.00 +/- 6.74 microm at 8 weeks and 64.10 +/- 8.51 microm at 24 weeks). The vascularization of the developing neuroepithelium may suggest increased metabolic demand during development and maturation of the olfactory neuroepithelium, and postnatal retreat of capillaries to the underlying lamina propria may suggest diffusion of nutrients and gases from blood vessels into the lamina propria and direct gaseous exchange from the atmosphere.     

The vomeronasal organ in the frog, Rana esculenta. An electron microscopy study

The ultrastructure of the vomeronasal organ (Jacobson's VNO) of the frog, Rana esculenta, was studied under the transmission and scanning electron microscope. Four cell types were identified: ciliated, bipolar, glial-like, and basal. Ciliated cells are unique to the frog VNO and show morphological evidence of secretion; bipolar (neuronal) cells are arranged in columns and reach the free surface of the epithelium with knobs bearing microvilli. The latter are in contact with amorphous material not described previously. Glial-like cells wrap bipolar cells in the epithelium and poorly differentiated basal cells are found just over the basal lamina. The vascular pump described in mammal VNO is not present at all in the frog VNO. We conclude that in the frog the VNO is closer to the reptilian than the mammalian VNO, although the frog VNO shows some unique morphological characteristics.     

Immunohistochemical study of human fetal vomerona structures the nasal septum, by applying neuron-specific beta3-tubulin antibodies

The functioning of Jacobson's or vomeronasal organ (VNO) in man is the subject-matter of discussion today. It is generally taken that VNO as an anatomic structure also remains in the adult; however, its receptor apparatus still degenerates in the fetal stage of ontogenesis. Nevertheless, the data available in the literature on the time and specific features of degenerative changes in the human fetal VNO are conflicting and ambiguous. The authors examined the human fetal nasal septum from the 8th week of development to birth, by applying the traditional histological procedures and neuron-specific beta3-tubulin antibodies. An immunohistochemical study could first show the receptor apparatus of the human fetal VNO at weeks 8-26 of development. The immunohistochemical study on a series of sections could reveal the regularities of spatial receptor distribution depending on the time of fetal development. In addition, the developed human fetal vomeronasal nerve and ganglion at weeks 8-26 were described, in human fetuses at weeks 8-26. The neuron-specific marker test has shown the nerve fibers departing directly from the VNO wall, which is inconsistent with the data available in the literature on vomeronasal nerve degeneration in this sign just after the 18th week of development.