Morphometric characteristics of thyroid C cells in cattle, dogs, horses, and pigs

The aim of the study was the morphometric assessment of C cells in cattle, dogs, horses, and pigs, which made it possible to complete the microscopic characteristics of C cells in these species. The material consisted of transverse sections of the left thyroid lobe (20 specimens/species), fixed in formalin, and subjected to standard histological processing. C cells were stained immunohistochemically with anti-calcitonin antibody. The following morphometric parameters were assessed: cell area (μm2), perimeter (μm), length (μm), width (μm), and circularity. In each case, 40 C cells were measured, and the mean value of each parameter was calculated for each species. C cells of each animal species were of different shapes: spindle-shaped in pigs, oval in dogs, and polymorphic in horses and cattle. Bovine C cells had cytoplasmic processes. It was shown that the area of C cells was largest in horses (88.83 ± 37.24) and dogs (86.92 ± 34.29), significantly larger than in cattle (83.5 ± 37.78) and pigs (73.7 ± 43.12). Their perimeter was largest in pigs (46.56 ± 19.35), smaller in cattle (41.59 ± 13.34) and horses (41.81 ± 10.15), and smallest in dogs (37.01 ± 8.72). In horses vs. cattle and horses vs. pigs, the differences were not significant. The most extended C cells were found in pigs (19.55 ± 9.57) and the shortest in dogs (12.67 ± 3.44). Their length in horses and cattle was comparable (15.29 ± 4.76 and 15.6 ± 6.61, respectively). Except for horses vs. cattle, these differences were significant. The width of C-cells was highest in dogs (6.69 ± 1.59) and lower in horses (5.85 ± 1.72), cattle (5.46 ± 1.6), and pigs (3.78 ± 1.14). Except for horses vs. cattle, the differences were significant. The circularity of C cells was highest in dogs (0.78 ± 0.1), followed by cattle (0.63 ± 0.94), horses (0.64 ± 0.14), and pigs (0.46 ± 0.16). These differences were not significant only in horses vs. cattle. The results show that the most significant variation in the parameters examined characterizes porcine and canine C cells. Despite their morphological diversity, equine and bovine C cells are morphometrically similar. The results obtained can provide reference values for further studies on the behavior of C cells in various physiological and pathological conditions in these animal species. They can serve as an additional tool for diagnosing tumors originating from C cells and be used in comparative histological research.