Examination of the vomeronasal organ in human fetal cadavers

The vomeronasal organ (VNO) is a peripheral sensory organ of the accessory olfactory system found in most vertebrates and is thought to be involved in the chemoreception of pheromones. The existence of the vomeronasal organ in humans and its development during fetal life is still a controversial issue. The aim of this study was to evaluate the presence and histologic structure of the vomeronasal organ in human fetuses. This study was conducted in 30 (14 males and 16 females) 10% formalin-fixed human fetuses (mean age, 23 weeks, 17-30 weeks) after obtaining ethical approval from Mersin University Clinical Research Ethics Committee (dated 18/09/2019 and numbered 2019/383) at Mersin University Faculty of Medicine, Department of Anatomy laboratory. Fetal nasal septums were exposed by surgical dissection and nasal septum samples were examined in formaldehyde in the Histology laboratory. The sections were examined with a light microscope, photographed and evaluated with a digital camera integrated into the microscope. The length, area, diameter, epithelial thickness of the surfaces facing the nasal septum cartilage and respiratory epithelium, and respiratory epithelial thickness of the stained preparations containing the vomeronasal organ were measured at x10 magnification in 5 different fields. The Shapiro Wilk test was used to determine whether the variables were normally distributed. Independent Sample t test and Mann Whitney U test were used to compare two groups. For the comparison of dependent variables, Analysis of Variance was applied. Analyses were performed with Statistica v.13.3.1 program and p<0.05 was accepted as statistical significance level. When nasal tissue samples of 30 fetuses were analyzed, VNO was detected in 24 samples (80%), 15 on both sides of the nasal septum and 9 unilaterally. Biostatistically, 24 VNOs were analyzed according to gender and whether they were bilateral or unilateral. The length, diameter, area of the organ, thickness of the epithelium facing the nasal septum cartilage and respiratory epithelium, and respiratory epithelial thickness were evaluated in the preparations with VNO. There were no statistically significant differences between the fetuses in VNO diameters (p=0.17), thickness of the epithelium facing the cartilage of the nasal septum (p=0.75), thickness of the epithelium facing the respiratory epithelium (p=0.619), thickness of the respiratory epithelium (p=0.715) and VNO areas measured at five different points (p=0.135). According to the results of pair group comparisons between genders, no statistically significant difference was found between male and female gender groups (p0,005). There was no statistically significant difference between the unilateral and bilateral groups in terms of epithelial thickness facing the cartilage of the nasal septum between measurements 2, 3, 4 and 5, while there was a statistically significant difference between measurements of epithelium 1 (p=0,033). Histologic evaluation showed that the Vomeronasal Organ was located in loose connective tissue on both sides of the nasal septum. In some preparations, this organ was observed as invagination of the respiratory epithelium surrounding the loose connective tissue. When the histologic structure of the Vomeronasal Organ was examined, it was seen as luminal structures with pseudostratified ciliated cylindrical goblet cell epithelium sitting on the lamina propria in loose connective tissue structure. In our study, we observed that the Vomeronasal Organ was present in the majority of human fetuses and its histologic structure was similar to the findings in the literature. Although the histologic structure of the Vomeronasal Organ has been revealed, further studies are needed to determine its clinical significance.