Reference Morphometric Parameters of Cerebellar Cortical Neurons in Domestic Birds: A Comparative Histomorphometric Study

Domestic birds are characterized by a highly developed functional organization of the central nervous system, which has evolved as an adaptation to complex sensorimotor activity, spatial orientation, and diverse locomotor patterns. One of the principal integrative centers of the brain is the cerebellum, whose morphofunctional status is determined by the cytoarchitectonic organization of its cortex and the quantitative characteristics of its neuronal populations. Despite the considerable number of studies devoted to cerebellar morphology, comparative histomorphometric characteristics of cerebellar cortical neurons in domestic birds remain insufficiently investigated, highlighting the relevance of the present study. The aim of this study was to establish reference morphometric parameters of cerebellar cortical neurons in domestic birds and to determine their species-specific characteristics based on a comparative histomorphometric analysis. The study was conducted on the cerebella of clinically healthy sexually mature domestic chickens (Gallus gallus domesticus), turkeys (Meleagris gallopavo), domestic ducks (Anas platyrhynchos domesticus), and domestic geese (Anser anser domesticus). Histological, neurohistological, morphometric, and statistical methods were employed for morphological evaluation. The cerebellar cortex of all examined species exhibited the typical trilaminar organization; however, significant interspecies differences were observed in the morphometric characteristics of neurons within the ganglionic (Purkinje cell) layer. The largest neuronal perikaryon volume was recorded in turkeys (1423.86 ± 81.60 µm³), followed by geese (1315.22 ± 88.53 µm³) and ducks (1139.49 ± 88.79 µm³), whereas the smallest value was observed in chickens (713.95 ± 68.58 µm³). Nuclear volume varied to a lesser extent and showed no statistically significant interspecies differences (P > 0.05). In contrast, the nuclear-to-cytoplasmic ratio demonstrated species-specific variability, with the highest value observed in ducks (0.087 ± 0.013), followed by turkeys (0.083 ± 0.024) and geese (0.079 ± 0.013), while chickens exhibited a significantly lower ratio (P < 0.001). The obtained findings expand current knowledge of the structural organization of the cerebellar cortex in domestic birds, provide reference histomorphometric parameters of cerebellar neurons, and may serve as a normative basis for comparative anatomical, histological, experimental morphological, and forensic veterinary investigations.