Development of lymphatic and haemopoietic organs in germfree models

Abstract

In the past, the problems of the morphological and functional development of primary and secondary lymphatic as well as haemopoietic organs were studied in a series of species reared under germfree conditions (guinea-pigs, chickens, mice, rats, piglets). The attention of research workers in this direction was concentrated primarily on those organ systems that are under conventional (CV) conditions in an intimate contact with the bacterial flora and where the absence of this stimulus could lead to morphological and functional changes (Luckey 1963). From a series of available data on this problem (Glimstedt 1936; Tajima 1955; Miyakawa et al. 1957; Gordon and Wostman 1958; Phillips 1959; Gordon 1959; ~terzl and Silverstein 1967; Pollard 1967; Plcasants 1968; Kruml et al. 1969; Cachava 1972; Rolls et al. 1975) we may summarize that the development of lymphatic system of germfree (GF) animals is retarded, at least with regard to secondary lymphatic organs; the most remarked differences between GF and CV animals were found in lymphatic organs draining the gastrointestinal tract. However, somewhat contradictory data are obtained already in a more detailed morphological description of these changes (GyllensSen 1950; Miyakawa 1957; Thorbecke 1959; Vaxler et al. 1978). I t is primarily the presence or absence of germinal centres in lymphatic follicles of GF animals and further the question of a possible detection of cells of the plasmocyte series in GF models. The differences in these data may be attributed mainly to the variability of experimental animal species but also to conditions of nutrition and adaptation of these animals to the environment of isolators for GF rearing (Gordon and Wostman 1958). The aim of our contribution to this problem is to compare the morphological and cytological development of lymphatic and haemopoietic organs in two of GF models that are most commonly used in this laboratory -GF precolostral piglets and GF rabbits, which markedly differ not only with regard $o classification in the zoological system but also due to the ~ype of nutrition and the conditions of rearing. In morphological estimation of the development of lymphatic and haemopoietie organs the technique of quantitative cytology was used (Kov~fi 1971) which was supplemented with classical histological techniques. As far as the definition of experimental models, rearing conditions and nutrition of GF piglets and rabbits is concerned, they are given elsewhere in this Symposium (St~ps163 1979; Trs 5ek and Mandel et al. 1979).