Calculation of morphometric measurements and stereological examination of volume values of hemispherium cerebri in guinea chickens and turkeys

Çelikezen B, Calculation of Morphometric Measurements and Stereological Examination of Volume Values of Hemispherium Cerebrii in Guinea Chickens and Turkeys, Van Yuzuncu Yil University, Institute of Health Sciences, Department of Anatomy, PhD Thesis, Van, 2025. In this study, 10 healthy adult female turkeys (Meleagris gallopavo) with an average body weight of 2700 g and 10 healthy adult female guinea fowls (Numida meleagris) with an average body weight of 1700 g were used. Following perfusion, the animals were fixed in formaldehyde, and the brains were removed via cranial dissection. The hemispheria cerebri were carefully isolated, and each hemisphere was divided into three parts for routine tissue processing. Using systematic and random sampling, every 30th block (1/30 proportion) was selected, and from each of the three subdivided parts of each hemisphere, 12 sections of 5 µm thickness were obtained. The sections were flattened in a gelatin-coated water bath, mounted onto coded slides, and stained using the hematoxylin-eosin (H&E) method. The stained sections were examined under an Olympus CX31 light microscope with a ×4 objective. Volume analyses were performed using the Shtereom I software based on the Cavalieri principle. The volumes of the cortex and medulla, as well as the total hemispheric volumes, were determined. To assess the reliability of the measurements, the coefficient of error (CE) was calculated. Normality of the data was confirmed using the Kolmogorov–Smirnov test. Group comparisons were conducted with independent-samples t-tests, and relationships between variables were analyzed using Pearson correlation. Results are presented as mean ± standard error, and statistical significance was accepted at p<0.01. In guinea fowls, the hemispheria cerebri were generally symmetrical; however, point-count (NOISE) differences favoring the hemispherium cerebri sinistrum in the medulla region suggested possible lateralization. Very strong positive correlations were observed between total volume and both cortex and medulla volumes in the hemispherium cerebri sinistrum, whereas these correlations were weaker but still significant in the hemispherium cerebri dextrum. Morphometric parameters were more strongly associated with volume in the sinistrum hemisphere, while the dextrum hemisphere showed a more balanced pattern. In turkeys, no significant differences were found between the hemispherium cerebri sinistrum and dextrum in terms of total, cortex, or medulla volumes and their ratios; NOISE values were also similar. Strong positive correlations were observed among the volumes in both hemispheres, indicating preserved structural symmetry. Overall, while some regions of the guinea fowl hemispheria cerebri may exhibit structural differences favoring the sinistrum hemisphere and potential lateralization, the hemispheres in turkeys are balanced and symmetrical in terms of volume and morphometry. Key Words: Guinea Fowl, Cerebral Hemisphere, Turkey, Morphometry, Stereology.