The Morphology and Distribution of Cutaneous Mechanoreceptors (Herbst and Grandry Corpuscles) in Bill and Tongue of the Mallard (Anas Platyrhynchos L.)

The morphology and distribution of two types of cutaneous mechanoreceptor, i.e., the Herbst and Grandry corpuscles, was studied in the bill and tongue of the mallard (Anas platyrhynchos L.). In general the morphological findings are in close agreement with most of the recent descriptions (MALINOVSKY, 1967; SAXOD, 1978; ABRAHAM, 1978). For the Herbst corpuscle the twisting of the most distal pair of cells of the inner core differs from most recent descriptions; for the Grandry corpuscle the variability in the formation of nervous discs between the specialized cells was more complex than has generally been reported and corresponds exactly to the description of VAN DE VELDE (1909). The distribution of both kinds of mechanoreceptor is discussed in relation to the peripheral branching pattern of trigeminal and glossopharyngeal nerves, which is also described. The very close correlation found between this distribution and the mechanical events during feeding (ZWEERS et al., 1977; ZWEERS & KOOLOOS, 1979) provides a firm morphological basis for a biocybernetic model (ZWEERS, 1979a,b) concerning the role of the tactile trigeminal system during feeding.