Luteinizing hormone-releasing hormone and innervation pathways in human prenatal nasal submucosa: factors of importance in evaluating Kallmann's syndrome.

A previous study has demonstrated that luteinizing hormone-releasing hormone (LHRH) is localized in the human bilateral vomeronasal organs in the nasal septum during a 4-week period of intrauterine life (22). The purpose of the present study was to elucidate the location of LHRH-expressing cells outside the vomeronasal organs, with special emphasis on the submucosa of the medial wall and roof of the nasal cavity. An additional aim was to study the innervation pathways in the same regions. Both regions can be affected in Kallmann's syndrome, which is characterized by hypogonadotropic hypogonadism (lack of LHRH) and often associated with anosmia. Histological sections of craniofacial regions (49 normal human fetuses, 6-19 weeks) were examined by immunohistochemical techniques for LHRH and for neuronal tissue (protein gene product 9.5, PGP 9.5). LHRH reactions were only seen in the septal submucosa extending from the vomeronasal organs to the olfactory bulb. There was a close spatiotemporal association between the occurrence of LHRH and neuronal tissue. From the rhino-olfactory epithelium separate nerve tissue extended to the olfactory bulb. It is suggested that the medial region of the nasal placode giving rise to the septal wall is always affected in Kallmann's syndrome, and in cases in which the phenotypic features are associated with anosmia, also the more lateral part of the nasal placode, from which the rhino-olfactory region originates, is affected.