The human vomeronasal organ: prenatal developmental stages and distribution of luteinizing hormone-releasing hormone.

The purpose of this study was to describe in 49 normal human prenatal specimens, 15-156 mm crown-rump length (CRL), the histomorphological development of the bilateral vomeronasal organ localized in the mucosa of the nasal septum. In addition, immunohistochemical localization of luteinizing hormone-releasing hormone (LHRH) was undertaken. The material was classified into five developmental stages (NAS I/V), based on the morphology of the nasal cavity. The vomeronasal organ was visible in stages NAS II, III and IV, corresponding to 21-102 mm CRL. Positive immunohistochemical reaction for LHRH neurons was pronounced in the vomeronasal organ in NAS II and III, corresponding approximately to fetal ages 8-12 gestational weeks (21-51 mm CRL). The study demonstrates in normal human prenatal material that LHRH can be recorded in the bilateral vomeronasal organs during approximately 4 weeks of intrauterine life.