Ultrastructure and stereology of leukocytes and platelets of normal foxes and a fox with a Chediak-Higashi-like syndrome.

Peripheral blood leukocytes and platelets from five normal foxes (Vulpes vulpes) and a fox with phenotypical characteristics of Chediak-Higashi syndrome (CHS) were examined by electron microscopy. Lymphocytes, monocytes, neutrophils, eosinophils, and platelets from the affected fox contained giant membrane-bound granules that resembled lysosomes. In eosinophils and neutrophils from the affected fox and a normal fox, relative cell volume occupied by granules and number of granules per unit area were calculated. Relative cell volume occupied by granules was the same in both foxes, but there were significantly fewer granules per unit area in the affected fox. This result is consistent with the idea that the giant granules arose from fusion of pre-existing, normal-sized granules, as occurs in CHS. In platelets from the affected fox, no osmiophilic granules were seen. Our findings agree with those from studies of CHS-affected blood cells in other species.