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Experimental granulomatous inflammation: The ultrastructure of the granuloma induced by injection of tubercle bacilli into freund adjuvant‐sensitised guinea‐pigs
Author(s) -
Browett P. J.,
Simpson L. O.,
Blennerhassett J. B.
Publication year - 1979
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.1711290405
Subject(s) - tubercle , granuloma , ultrastructure , bacilli , granulomatous inflammation , inflammation , granulomatous disease , freund's adjuvant , guinea pig , adjuvant , pathology , medicine , tuberculosis , granuloma formation , microbiology and biotechnology , immunology , biology , sarcoidosis , bacteria , genetics
Injection of killed tubercle bacilli into a sensitised guinea pig produces a characteristic biphasic response with the development of an organised epithelioid cell granuloma in the second phase. Previous sensitisation to tubercle bacilli is a requirement for development of the organised granulomatous response. The main components of the granuloma are epithelioid cells, although multinucleate cells of both Langhans and foreign-body type are present. Epithelioid cells appear to evolve from monocytes, probably in the sequence: (a) monocyte, (b) monocytic transition form, (c) immature epithelioid cell, (d) mature epithelioid cell, although some may possibly develop through a macrophage stage. Differentiation of monocytes into epithelioid cells is a continual process in the experimental tuberculous granuloma with monocytes migrating into the lesion at all stages examined. Epithelioid cells are not obviously phagocytic. Their differ4ntiation has a phase suggestive of biosynthesis during which RER is the predominant cytoplasmic component. This is followed by a storage/secretory phase in which the cytoplasm contains membrane-lined vesicles and prominent Golgi apparatus. The vesicles and, where distended, the RER laminae contain a lightly staining, finely granular material the biological activity of which is unknown.