The Morphogenesis of Circumvallate Papillae and the Differentiation of Taste Buds in the Pig at 41 to M Days of Prenatal Development

Tichy, F.: The Morphogenesis of CircumtJallate PapiUae and the Differentiation of Taste Buds in the Pig at 41 to 64 Days of Prenatal DefJe/opment. Acta vet. Bmo, 60, 1991: 99-1()()' Samples of tongues collected from porcine foetuses at 41, 44, 50, 53, 57 and ~ days after fc:rtilization were examined for the appearance and development of surface lingual structures. At each of the stages studied, the morphogenesis of circumvallate papillae and the differentiation of taste buds were recorded. Attention was paid to the formation of gustatory glands· and their ducts and to the development of the furrow encircling the circumvallate papilla. The differentiation of the other types of lingual papillae was also studied. The formation of taste buds in the epithelium coincided with the shape differentiation of circumvallate papillae. The buds appeared first in the dorsal surface epithelium and later in the wall epithelium. The number of differentiating buds within one papilla increased with foetal age. Different cell types composing the taste bud could be distinguished soon after the bud was formed. The circUmvallate papilla was either formed as a unified structure of typical appearance or had first a composite base later giving rise, by fusion of its segments, to the typical papilla. The other, lingual papillae developed at later stages than the circumvallate papillae. Tongue, circumtJallate papilla, taste bud, differentiation, pig The structure, function and distribution of taste buds were studied as early as in the second half of the last century. The first observations were made in fish (Schulze 1863), then in mammal' (Loven 1868; Schwalbe 1868). The general information on the structure of the taste organ in some species of laboratory mammals and in man were obtained by means of light microscopy at the beginning of this century (Kolmer 1910; Retzius 1912; Heidenhain 1914). Pro~s in understanding the mechanism of taste perception occurred with the advent of techniques ailowing observations at the ultrastructural level. Many of data on the submicroscopic structure of taste buds together with characterization of their cell types (Beidler and Smallman 1965; De Lorenzo 1958; Engstrom and Rytzner 1956; Fahrmannand Schuchard 1967; Farbman 1965a; Farbman and Vonkers 1971; Fujimoto and Murray 1970; Murray 1969,1971, 1973; Murray and Murray 1960, 1967, 1970; Murray et aI. 1969; Takeda and Hoshino 1975; Trujillo-Cenoz 1957; Uga 1966,1969) have provided the grounds for the development of biochemical and physiological methods for investigation of taste perception (Beidler 1970; De Han and Graziadei 1971,1973; Desgranges 1966; Hirata and Nada 1975; Spoendlin 1970; Takeda 1976; Beauchamp and Cowart 1986). All these studies have contributed significantly to the understandiDg of processing and transport of taste stimuli within the bud. The most important information and methods of investigation have been reviewed and preSented in textbooks (Cormack 1984; Banks 1981; Smolich and Michael 1985; Rooss and Reith 1985).