Inclusion bodies in trachoma.

THE epithelial-cell inclusion, which is characteristically found in the early stages of trachoma was first described by Halberstaedter and Prowazek (1907). Since that time, a considerable literature concerning the nature of these bodies has accumulated. It is generally conceded that they consist of virus particles together with material elaborated by the virus and/or produced by the parasitized cell as a result of interference with its metabolism. The concept of developmental phases in the life-history of the inclusion body was first described by Lindner (1910). At an early stage the inclusion body is composed of larger particles (06 16 ,u) staining dark blue with the Giemsa mixture-the " initial bodies "-which are associated with a basophilic matrix-the so-called " plastin " material of Halberstaedter (1912). The initial bodies are considered to fragment in some way, thereby giving rise to the smaller particles called "elementary bodies" (0-25 4u), which stain in a manner similar to that of nuclei with the Giemsa mixture, i.e. magenta-red (" Romanowsky effect "). Lindner's observations have in general been confirmed by those of Thygeson (1934a), and have received indirect support from the parallelism afforded in the maturation stages described for the inclusion body in inclusion conjunctivitis (Thygeson, 1934b), and also by the somewhat similar cyclical changes described for the inclusion bodies in psittacosis (Bedson and Bland, 1932; Bland and Canti, 1935), and lymphogranuloma inguinale (Findlay and others, 1938). Indeed it is largely because of this similarity in the pleomorphism of their inclusion bodies that the large viruses of these four diseases are grouped together taxonomically. Rice (1936) and later Thygeson (1938) demonstrated the presence of a carbohydrate matrix in which the virus particles lie; using histochemical methods they identified this substance as glycogen. Grossfeld (1950), using the Feulgen technique, found the elementary bodies to contain desoxyribose nucleic acid (this author considered the initial bodies and elementary bodies to be similar in nature, differing essentially only in size and in their degree of basophilia). In this present study, histochemical methods were used to demonstrate both types of nucleic acids (desoxyribose nucleic acid (D.N.A.) and ribose nucleic