Morphology and cytology of the nasal cavity and vomeronasal organ in juvenile and adult blind mole rats (Spalax ehrenbergi).

The blind mole rat (Spalax ehrenbergi) is a fossorial solitary rodent which exhibits extensive intraspecific aggression and uses scent markings to deter contraspecific invaders. Mole rats of different ages were captured near Tel Aviv, Israel, and sacrificed by an overdose of Xylazine hydrochloride. Olfactory epithelium sites from the nasal cavity (NC) and the vomeronasal organ (VNO) were dissected and fixed for light and electron microscopy. The mole rat's olfactory epithelium of the NC consists of several cell types, of which two types are supporting cells that comprise both microvilli and cilia but differ in staining and the presence of rough endoplasmic reticulum. The third type has no cilia. Secretory goblet cells were frequent among supporting cells of adults alone. Two types of receptor cells protrude into the NC with olfactory knobs at their apical region; one type has up to 177.6 +/- 9.4 cilia per knob plus microvilli, while the other type has only microvilli. The third type of sensory cell has no knob and contains microvilli only. The basal epithelium layer consists of short-bodied cells with round nuclei. The VNO of the mole rat is situated beneath the nasal septum, consisting of supporting, sensory, and basal cell types, with many cilia at the apical portion. At its anterior part, the VNO is connected to the NC by narrow canals. The abundance of cilia and microvilli in the mole rat olfactory cells provides the first anatomical evidence for their olfactory acuity. Such acuity is important in mole rats, compensating for their loss of vision and enabling them to detect and avoid rivals prior to potential aggressive encounters as well as to select food plants during foraging.