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The accessory olfactory bulb (AOB) is the first neural integrative center for the olfactory-like vomeronasal sensory system. In this article, we first briefly present an overview of vomeronasal system organization and review the history of the discovery of mammalian AOB. Next, we briefly review the evolution of the vomeronasal system in vertebrates, in particular the reptiles. Following these introductory aspects, the structure of the rodent AOB, as typical of the well-developed mammalian AOB, is presented, detailing laminar organization and cell types as well as aspects of the homology with the main olfactory bulb. Then, the evolutionary origin and diversity of the AOB in mammalian orders and species is discussed, describing structural, phylogenetic, and species-specific variation in the AOB location, shape, and size and morphologic differentiation and development. The AOB is believed to be absent in fishes but present in terrestrial tetrapods including amphibians; among the reptiles AOB is absent in crocodiles, present in turtles, snakes, and some lizards where it may be as large or larger than the main bulb. The AOB is absent in bird and in the aquatic mammals (whales, porpoises, manatees). Among other mammals, AOB is present in the monotremes and marsupials, edentates, and in the majority of the placental mammals like carnivores, herbivores, as well as rodents and lagomorphs. Most bat species do not have an AOB and among those where one is found, it shows marked variation in size and morphologic development. Among insectivores and primates, AOB shows marked variation in occurrence, size, and morphologic development. It is small in shrews and moles, large in hedgehogs and prosimians; AOB continues to persist in New World monkeys but is not found in the adults of the higher primates such as the Old World monkeys, apes, and humans. In many species where AOB is absent in the adult, it often develops in the embryo and fetus but regresses in later stages of development. Finally, new areas in vomeronasal system research such as the diversity of receptor molecules and the regional variation in receptor neuron type as well as in the output neurons of the AOB and their projection pathways are briefly discussed. In view of the pronounced diversity of size, morphologic differentiation, and phylogenetic development, the need to explore new functions for the vomeronasal system in areas other than sexual and reproductive behaviors is emphasized.

Turbinals (scroll bones, turbinates) are projections from the lateral wall of the nasal fossa. These bones vary from simple folds to branching scrolls. Conventionally, maxilloturbinals comprise the respiratory turbinals, whereas nasoturbinals and ethmoturbinals comprise olfactory turbinals, denoting the primary type of mucosa that lines these conchae. However, the first ethmoturbinal (ETI) appears exceptional in the variability of it mucosal covering. Recently, it was suggested that the distribution of respiratory versus olfactory mucosae varies based on body size or age in strepsirrhine primates (lemurs and lorises). The present study was undertaken to determine how the rostrocaudal distribution of olfactory epithelium (OE) versus non-OE scales relative to palatal length in strepsirrhines. Serially sectioned heads of 20 strepsirrhines (10 neonates, 10 adults) were examined for presence of OE on ETI, rostral to its attachment to the nasal fossa wall (lateral root). Based on known distances between sections of ETI, the rostrocaudal length of OE was measured and compared to the length lined solely by non-OE (primarily respiratory epithelium). In 13 specimens, the total surface area of OE versus non-OE was calculated. Results show that the length of non-OE scales nearly isometrically with cranial length, while OE is more negatively allometric. In surface area, a lesser percentage of non-OE exists in smaller species than larger species and between neonates and adults. Such results are consistent with recent suggestions that the olfactory structures do not scale closely with body size, whereas respiratory structures (e.g., maxilloturbinals) may scale close to isometry. In primates and perhaps other mammals, variation in ETI morphology may reflect dual adaptations for olfaction and endothermy. Anat Rec, 290:215-237, 2007. 2007 Wiley-Liss, Inc.

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...

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The terms "microsmatic" and "macrosmatic" refer to species with lesser or greater levels, respectively, of olfactory function. Historically, primates are considered microsmats (olfactory sense reduced) with a concomitant increased emphasis on vision. The olfactory bulbs (forebrain centers that receive peripheral olfactory input) are proportionately smaller in primates compared to most other mammals. Similarly, the regions of the nasal cavity that are covered with olfactory epithelium (containing receptor cells) have proportionately less surface area in primates than other mammals. Thus, the generalization that primates are microsmatic is most frequently stated in terms of the proportional rather than absolute size of olfactory structures. Yet the importance of scaling to body size is unclear in regard to the chemical senses such as the olfactory or vomeronasal systems-do chemosensory structures such as olfactory bulbs and olfactory epithelium exhibit the same neural relationship to body mass that is seen for neural tissues that supply innervation to musculature or the skin? Previous studies examining neuronal density, volume, and/or surface area of the olfactory epithelium illustrate that different conclusions may be supported based on the parameter used. Plots of olfactory bulb volume versus body mass that generated for large-scale taxonomic studies or growth studies benefit from body mass (or total brain volume) with a comparative perspective. However, our examination of proportional versus absolute measurements implies that in comparisons within taxa, body size adjustments needlessly distort the data. As a final consideration, another embryonic derivative of the nasal placode, the vomeronasal organ, may warrant consideration regarding a definition of microsomia versus macrosomia. Anat Rec (Part B: New Anat) 279B:24 -31, 2004.

Melatonin is a natural substance ubiquitous in distribution and present in almost all species ranging from unicellular organisms to humans. In mammals, melatonin is synthesized not only in the pineal gland but also in many other parts of the body, including the eyes, bone marrow, gastrointestinal tract, skin and lymphocytes. Melatonin influences almost every cell and can be traced in membrane, cytoplasmic, mitochondrial and nuclear compartments of the cell. The decline in the production of melatonin with age has been suggested as one of the major contributors to immunosenescence and development of neoplastic diseases. Melatonin is a natural antioxidant with immunoenhancing properties. T-helper cells play an important role for protection against malignancy and melatonin has been shown to enhance T-helper cell response by releasing interleukin-2, interleukin-10 and interferon-γ. Melatonin is effective in suppressing neoplastic growth in a variety of tumors like melanoma, breast and prostate cancer, and ovarian and colorectal cancer. As an adjuvant therapy, melatonin can be beneficial in treating patients suffering from breast cancer, hepatocellular carcinoma or melanoma. In this paper, a brief review of recent patents on melatonin and cancer has also been presented.