Narial pillow
Narial pillows are mainly structures in the area of the nostrils of rodents and rabbits, which can be traced back to the internal pars of the nasal mirror . They consist of two legs fused together in the middle, the upper crus superius and the lower crus inferius . In rodents, the superior crus can have a rounded area with rhinoglyphs and referred to as the circular areola . The tactile perception serving the Narialkissen with a combination of are Merkel cells , Pacinian corpuscles and free nerve endings provided.
Narial cushions represent a jointly derived feature of the rodents and rabbits grouped together as glires . In terms of developmental history, the pars internarica of the nasal mirror was initially divided increasingly from the pars supranarica by a shallow, transverse furrow . The furrow developed into the deeper sulcus transversus and the protruding narial cushions were created by reducing parts of the pars supralabialis and by deepening the central sulcus medianus . The rhinoglyphs of the nasal mirror, which were associated with the sense of touch, were lost except on the narial pillows. With the reduction of the nasal mirror and the limitation of the sense of touch to protruding areas, the loss of rummaging, of rummaging through the ground with the snout, went hand in hand. This is believed to be related to the development of the incisor teeth , which also serve as tools for processing and exploration.
Especially in rodents, the narial cushions are transformed in many ways. Originally they are approached, protruding and two-legged. Secondarily, they can be displaced sideways, connected to the supranaric region due to the absence of the sulcus transversius , or fused together. They can be reduced to cushions, located in the inner corner of the nostrils and only consist of one leg.
literature
- Manfred Ade: Macroscopic examinations on the Rhinarium of the Glires (Rodentia and Lagomorpha) . Science and technology, Berlin 1998, ISBN 3-89685-463-1 .