The fine structure of the ookinete of Parahaemoproteus velans (= Haemoproteus velans Coatney and Roudabush) (Haemosporidia: Haemoproteidae)

Abstract

The ookinete of Parahaemoproteus velans is bounded externally by a trilaminar membrane, beneath which lies a fibrillar zone. Below this zone and forming the inner surface of the pellicle is a second, dense, membranelike layer. The specialized apical region of the ookinete is modified into a thickened "caplike" structure. The inner layer of the pellicle in this region is thickened and wavy in appearance. In a sub-pellicular space in the cap region lie about 27 elongate cylindrical structures, and beneath these about 50 microtubules ring the cytoplasm. Numerous dense spherical bodies are located in the anterior cytoplasm of the parasite. A large, more or less central nucleus, often containing microtubular elements, lies in a cytoplasm richly endowed with granular endoplasmic reticulum. Two or more areas containing a "crystalloid" material lie anterior and posterior to the nucleus.