The human vomeronasal organ. III. Postnatal development from infancy to the ninth decade

Abstract

The large literature on the human vomeronasal organ (VNO) offers little consensus as to its persistence in the adult. We have already documented the existence of the VNO from embryonic day 33 through the neonatal stages. This has now been extended to human adults : 27 cadaver nasal septa, aged 2-86 y, were either dissected or decalcified, serially sectioned, stained and examined. The consistent presence of the VNO is reported as a homologue, in the form of a duct-like structure on the nasal septum at all ages. Also reported are size variability, pronounced bilateral asymmetry, a nonchemosensory pseudostratified ciliated epithelium with considerable structural variation and generally without medial-lateral differentiation, nasal septal glands opening into the VNO lumen, a lack of correlation between postnatal age and VNO size, visualisation of the human VNO with certainty by histological means alone, and a minute opening as its only visible surface feature. The human VNO is a discrete structure that should not be confused with the nasopalatine fossa, the septal mucosal pits or VNO openings.Key words : Human VNO ; postnatal development ; adult VNO dimensions ; VNO homologue. To comparative anatomists, the vomeronasal organ (of Jacobson, VNO) holds a fascinating place in vertebrate ontogeny and phylogeny (Jacobson, 1811(Jacobson, , 1813Ko$ lliker, 1877 ; Potiquet, 1891 ;Chouard et al. 1972 ;Bhatnagar & Reid, 1996 ;Trotier et al. 1996 ;Keverne, 1999 ;. Although the human VNO has been investigated for over 200 years, much confusion and many inaccuracies have been perpetuated as to its persistence, identification, location, size, morphology and function (Nakashima et al. 1985 ;Garcia-Velasco & Mondragon, 1991 ;Boehm & Gasser, 1993 ; GarciaVelasco & Garcia-Casas, 1995 ;Berliner et al. 1996 ;Kjaer & Fischer-Hansen, 1996 ;Jahnke & Merker, 1998, 2000 Monti-Bloch et al. 1998 a, b ;Won et al. 2000 ; Zbar et al. 2000). Textbooks of human embryology and gross anatomy (Hamilton & Mossman, 1972 ;Goss, 1972 ;Williams et al. 1995 ; Correspondence to Dr Kunwar Bhatnagar, Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Health Sciences Center, Louisville, KY 40292, USA. Tel. : 001 502 852 5174 ; fax : 001 502 852 6228 ; e-mail : bhatnagar!louisville.edu Sadler, 2000) have either described the VNO incorrectly or stated that it is not present in the human adult. In addition, investigators including GarciaVelasco & Mondragon (1991), Takami et al. (1993), Berliner et al. (1996, Monti-Bloch et al. (1998 a, b), Grosser et al. (2000) and Jahnke & Merker (1998, 2000 have drawn conclusions concerning the physiology and pharmacology for a structure they probably misidentified as the human VNO in the living subject. Our studies indicate that the erroneously reported location and attributes of the VNO have created confusion.Earlier, we investigated the prenatal development of the human VNO and determined that it is present at all stages, and corroborated the reports of Johnson et al. (1...

Comparative study of lectin reactivity in the vomeronasal organ of human and nonhuman primates

“…Although the precise significance of the lectin patterns described herein for primates is not known at this time, our findings support other recent studies contending that the human VNO is nonchemosensory in nature (Trotier et al, 2000;Bhatnagar and Smith, 2001;Smith et al, 2002;Witt et al, 2002).…”

“…Prior to this, most specimens had been stored in 10% formalin and were originally fixed by immersion in the same fixative. Exceptions were the adult humans, which had been embalmed for anatomical study in gross anatomy courses, the 2-year-old child, which was originally fixed in Bouin's fluid (Bhatnagar and Smith, 2001), and the adult chimpanzee, which was frozen prior to fixation (Smith et al, 2002). Tissues were decalcified using a formic acid solution, dehydrated in an ethanol series, cleared in xylene, and embedded in paraffin.…”

“…In previous reports, the VNOs of humans and chimpanzees have been shown to comprise a homogeneous, pseudostratified, and (mostly) ciliated epithelium (Johnson et al, 1985;Bhatnagar and Smith, 2001;Smith et al, 2001bSmith et al, , 2002. This epithelium, based on light microscopy and using traditional staining methods, more strongly resembles respiratory epithelium than vomeronasal neuroepithelium found in other mammals (Bhatnagar and Smith, 2001).…”

“…This epithelium, based on light microscopy and using traditional staining methods, more strongly resembles respiratory epithelium than vomeronasal neuroepithelium found in other mammals (Bhatnagar and Smith, 2001). Yet, based on a series of physiological studies, one group of authors has concluded that the human VNO is functional, i.e., with at least some functional similarity to the VNO of other mammals (Berliner et al, 1996;Monti-Bloch et al, 1998;Grosser et al, 2000).…”

Development of the neurons controlling fertility in humans: new insights from 3D imaging and transparent fetal brains

“…Here, we show that during human fetal development the VNO and the AOB are indeed anatomically connected, since NRP2-immunoreactive vomeronasal fibers project to the dorsal OB, as reported in rodents (Cloutier et al, 2002). The VNO also contains strongly Ki67-positive and SOX2-positive putative neurogenic precursors, in agreement with the increase in volume of the human fetal VNO epithelium with age and its persistence at least until birth (Bhatnagar and Smith, 2001;Smith and Bhatnagar, 2000).…”