E12 technique: an aid to study sinuses of psittacine birds

Infraorbital sinus infections, which form the bulk of upper respiratory tract infections in companion birds, are commonly encountered in clinical practice and often require medical and/or surgical management. The infraorbital sinus with its dorsal drainage into the nasal cavity makes it difficult to treat these infections. The sinus has various compartments throughout the skull, and subcutaneous tissue. As an aid in determining the location and extent of the sinuses of the parrot and macaw, a corrosion cast of the infraorbital sinus was made. Also, computed tomography (CT) images of cadaver heads were completed at 2-mm scans. Prior to sectioning for sheet plastination, the infraorbital sinus of one half of the imaged heads was injected with a mixture of colored epoxy. The specimens were frozen (-25 degrees C) prior to sawing 2-mm-thick sections which corresponded to the CT scans. The sections were dehydrated, impregnated and sheets prepared using the standard E12 technique. The slices were used to identify the compartments of the infraorbital sinuses and to aid identification of such on the CT images.