Morphometrics and First Ultrastructural Characterizations of Intra-Erythrocytic Stages of So-Called Haemogregarina damiettae Ramadan et al. (1996) With Special Reference to Its Cytopathological Effects on the Infected Erythrocytes.

The current study provides the first ultrastructural observations on the intraerythrocytic stages of so-called Haemogregarina damiettae and their cytopathological effects on the infected erythrocytes (IEs) in addition to the recording of new morphometric data. The intraerythrocytic stages are attributed to the immature forms or trophozoites (Ts), and mature gamonts (Gs). Ts are typically bowling-bottle shaped with nucleus (TN) occupying its globose part, while Gs are typically banana- shaped. Ts measure 9.60-13.77 (12.53 ± 0.95) × 3.29-5.72 (4.18 ± 0.52) μm, however, Gs measure 14.05-16.13 (15.15 ± 0.60) × 3.38-4.74 (4.06 ± 0.32). Parasite shape index, nuclear/body, and nuclear/cytoplasmic ratio are calculated for both Ts and Gs. Moreover, shape index, nuclear/erythrocytic ratio, nuclear/cytoplasmic ratio are determined for both uninfected erythrocytes (UIEs) and IEs. At ultrastructural level, the parasite exhibited numerous unique features such as the presence of unsutured covering capsule (Ca), intracytoplasmic membraneous structures (ICM), and electron-dense connecting structures (CS) between the degradable cytoplasmic mass (DC) of IEs and parasite itself which are postulated to perform a feeding function. The cytopathological effects on IEs include erythrocytic shape distortion, hypertrophy, dehemoglobinization, as well as nucleus size and shape changes. Erythrocytic karyolysis is confirmed by light and electron microscopy. In addition, all IEs showed characteristics two lateral polar projections or flape-like extensions (FE) supported by microtubules-like structures. Moreover, parasitophorous vacuole membrane (PVM) form in most cases a thick internal lining (IL) of homogenous electron-lucent materials at parasite-facing side and knob-like thickenings (K) of electron-dense materials on erythrocytic cytoplasm-facing side.