Amazingly, they all produce an identical chemical. Production by insect females signals a readiness to mate while the female elephant secretes the same chemical in her urine just before ovulation. The purpose of the VNO seems to be dedicated to detecting those chemical signals involved in sexual and territorial behaviour. Such pheromones can make the prairie vole's uterus triple in size, and stimulate her to ovulate within two days. One school of thought supports Ruysch, another believes that the organ is none existent or vestigial.
Recent studies do, however, now seem to be coming down in favour of the first school of thought.
The human VNO consists of two small sacs about 2 mm deep about 1 cm up from the nostrils, opening into shallow pits with tiny openings in their centres that are about 0.1 mm across. When anatomist Dr David Berliner was investigating the composition of human skin he found that when he left vials containing skin extracts open, the feelings of himself and people round about seemed to change - becoming warmer and friendlier. Such feelings were reduced if the vials were covered. In the future, we may well be wearing minute but nevertheless potent quantities of human pheromone in order to attract our Valentines. 1992 Comments on the article to the author Anne Bruce Microscopy UK Front Page Micscape Magazine Article Library Microscopy UK or their contributors.