The development of eosinophils in the bone marrow of the fowl and the duck.

The eosinophils present in the bone marrow of the fowl and the duck were classified into various maturational stages according to the shape of their nuclei and the content of their cytoplasm. The granules appeared to develop from dilations located at the extremities of the cisternae of the Golgi apparatus, whence they broke free, forming vesicles. By condensation they progressed from a flocculent type of granule to the definitive spherical homogeneous primary granule. Various staining techniques were applied in this study and it was found that, as in mammals, granules of two distinct types were present in developing avian eosinophils, and that they matured by transition from a primary granule to a specific stage.