[Comparative anatomical studies on the Jacobson organs of Nycticebus coucang Boddaert, 1785 (Prosimiae, Lorisidae) and Galago crassicaudatus E. Geoffroy, 1812 (Prosimiae, Lorisidae). I. Nycticebus coucang].

The goal of this research was to study the macroscopic and microscopic anatomy of the vomeronasal organ in Nycticebus coucang. Based on numerous measurements in cross-sections of all parts of the organ, three-dimensional graphs of the vomeronasal cartilage, the organ and the system of blood-vessels, situated around the organ, were drawn. Nycticebus has a well developed vomeronasal organ exhibiting a well developed sensory epithelium. The oral end of the organ opens into the middle part of the nasopalatine duct, which has an open connection with the cavum nasi and the cavum oris. The cartilago paraseptalis is connected with the cartilago ductus nasopalatini by the sickle-shaped part of the cartilago paraseptalis. An "outer bar", which is present in the vomeronasal cartilage of Tupaia, is absent in Nycticebus. The oral part of the organ contains nonciliated, pseudostratified epithelium with secretory crypts and goblet cells. In the main part of the organ the dorso-lateral wall consists of nonsensory, nonciliated, pseudostratified epithelium, while the sensory epithelium is situated in the dorsolateral wall. Serous glands, which are situated dorsal to the organ, open into the organ at its dorsal margin. Caudal to this part there is a long part of the organ without sensory epithelium. At its caudal end the organ is branched. The sensory epithelium of the vomeronasal organ is thicker than the sensory epithelium of the nose. It contains a nucleus-free space between the nuclei of supporting cells and the nuclei of sensory cells. The sensory epithelium contains about 92 000 receptor cells/mm2. Capillaries could not be seen in the epithelia of the organ. The vessels, which accompany the organ, are veins and capillaries. The dorsal veins exhibit thicker walls and a wider lumen than the ventral ones and are therefore better suited for the pumping-mechanism, as suggested by BROMAN (1920). Connective tissue, surrounding the organ, aids the pumping-mechanism of the veins.