Histoplasma capsulatum in Tissue Culture. ∗

Abstract

Discussion and Conclusions

A study of chick embryo and horse placental tissue, when cultivated in tissue culture with H. capsulatum by the cover-glass method, has revealed that fibroblasts or fibroblast-like cells of the outgrowth contain yeast cells of this organism in the cytoplasm. It is of interest to note that sections of infected tissues from systemic histoplasmosis rarely, if ever, show yeast cells in fibroblasts. Whether or not these intracellular yeasts can continue to multiply within the fibroblast, or are ultimately destroyed, remains to be determined. Similarly, whether or not the fibroblast which contains yeast cells can divide further, or undergoes degeneration, is not yet known. An explanation for the unique type of colconial morphology of H. capsulatum seen in the cover-glass cultures, cannot be given at this time. This phenomenon is not dependent upon the presence of living tissues, since the sac-like type of colonies were observed in the controls which lacked tissue fragments. Of possible significance is the fact that this type of colony occurred only when the inoculated yeast cells were fixed in situ and surrounded by clotted plasma; in the supernatant of the flask cultures, only free, individual yeast cells were seen. Further work is in progress in an attempt to clarify tshese problems.