Straightforward identification of structures of the striatum in bovine and equine forebrains: Guidance to trimming

Abstract

Standardizing trimming the brain for histological diagnosis of neurological diseases is challenging for veterinary pathologists. The striatum is a set of subcortical nuclei of the forebrain, formed by bundles of nerve fibers and gray matter, which consist of the internal and external capsules, caudate, lentiform, and claustrum nuclei. The striatum is related to motricity, which refers to the neural circuits of the extrapyramidal pathways. In domestic animals, the extrapyramidal pathways are of great importance in gait. From the ventral surface of the brain, they are located deep in a strip of the telencephalon corresponding to the olfactory trigone. Bovine and equine brains were routinely formalin-fixed, weighed and measured. Herein, we report a guide for bovine and equine brains’ neuroanatomic trimming and striatum histomorphology. Trimming was performed, and the sections were routinely processed for histology. We used the cross-section rostral to the optic chiasm as the site of choice for histologic sampling to identify the striatum structures. The forebrains were sectioned, and the standard histologic cassette was positioned horizontally or vertically to frame a greater diversity of structures. The histologic slides were labeled with structures of the striatum (caudate nucleus, internal capsule, lentiform nucleus, external capsule and claustrum). Regarding the brain size, handing the cassette orientation over to the forebrain allows the verification to shift the position or collect a second striatum sample for histology.