The Morphogenesis of Circumvallate Papillae and the Differentiation of Taste Buds in the Porcine Foetus from Day 76 till Birth and in the Adult Pig

Abstract

Tichy F.: The Morphogenesis of Circumvallate Papillae and the Differentiation of Taste Buds in the Porcine Foetusfrom Day 76 till Birth and in the Adult Pig. Acta vet. Brno, 60, 1991: 307-315.The development and morphology of some lingual structures were studied in the tongues of porcine foetuses at 76, 81 and 94 days after fertilization, of piglets 2 days after birth and of adult pigs. Special attention was given to the morphogenesis of circumvallate papillae and the differentiation of taste buds in papillary epithelium. The formation of the other types of papillae, and the development of the lamina propria mucosae and the related structures were also investigated.Taste buds prevailed in the wall epithelium of the circumvallate papilla, while in its dorsal surface they occurred only occasionally during the first stages of the period studied. The amount of taste buds increased gradually in foliate papillae. In the period under study taste buds showed distinct differentiation of their cells.The porus gustatorius formed immediately after the taste bud reached the surface of epithelium."Secondary" ducts of the gll. gustatoriae observed in circumvallate papillae in the late prenatal periods were present till birth.The development of the other lingual papillae followed that of circumvallate papillae. Tongue, papillae, taste bud, development, swineThe structure and composition of lingual mucosa is well understood at the levels of both light and electron microscopy. The basic information on the structure of the taste organ, based on electron microscopic observations, in laboratory animals as well as in man was reported early in this century (Kolmer 1910;Retzius .1912;Heidenhain 1914).The result of a number of investigations into the ultrastructure of taste buds in some animal species (Beidler and Smallman 1965;De Lorenzo 1958;Farbman 1965a, Farbman and Tonkers 1971;Fujimoto and Murray 1970;Murray 1969Murray , 1971Murray , 1973Murray and Murray 1960, 1967Murray, Murray and Fujimoto 1969;Takeda and Hoshino 1975;Uga 1966Uga , 1969 and others) contributed significantly to the understanding of taste perception mechanisms. They provided grounds for the development of methods for studying biochemistry and physiology of taste perception (Beidler 1970;De Han and Graziadei 1971;Hirata and Nada 1975;Spoendlin 1970;Takeda 1976; Beauchamp and Cowart 1986, and others).Attention has also been paid to the development of the taste organ in man and various mammalian species (Bredler and Smallman 1965;Farbman 1965bFarbman , 1971 Takeda 1972 and others).Less information is available on the development of mucosal structures of the tongue in relation to periods of development in farm animals. Particularly poor are data on the time of commencement of taste buds and on the changes in the gustatory receptor occurring during ontogenesis.

Light and scanning electron microscopic studies on the lingual papillae of 80-day-old wild pig fetal siblings

“…Thin tubular secondary ducts that open out from the base of the indentations were first observed on fetal day 64 and they have been documented to disappear in mature pigs (3,17). In our study, there were 2 vallate papillae in the 80-day-old fetuses.…”

“…After this stage, a few taste buds were observed on the dorsal surface of the papillae. Another report (17) indicated that the tips of the taste buds reached the epithelial surface in 76-day-old fetuses, and after day 81, taste pores developed on rare occasions. Thus, light and dark cells of the taste buds, which began differentiating after day 53 of fetal age, became evident on day 76.…”

“…These have also been observed in the fetal and postnatal periods of humans and animals, indicating the presence of the marginal papillae, which usually disappear later on. Furthermore, the lingual papillae of the mature domestic pig, domestic pig fetus, and mature wild pig (2,3,8,17) have been documented via light and scanning electron microscopic observations. Likewise, this study investigated the morphological characteristics of the lingual papillae in wild pig fetuses using light and scanning electron microscopy techniques.…”

“…The literature has documented that the number of vallate papillae differs greatly among species (8,(20)(21)(22)(23)(24), but it has been reported to be 2 for pigs (2,3,17,25,26). One study indicated the presence of drafts of these papillae in 44-day-old pig fetuses.…”

“…The literature has reported tubercles and indentations at various lengths along the dorsal surface of the vallate papillae (2,3,17,26). Thin tubular secondary ducts that open out from the base of the indentations were first observed on fetal day 64 and they have been documented to disappear in mature pigs (3,17).…”