The intra-pineal calcification is a well-known
phenomenon in mammals, however it is almost
completely unknown in birds. The aim of the present
work was to analyze morphology and genesis of the
pineal concretions in the turkey. The studies were
performed on the pineals collected from one-year-old
turkeys (Meleagris gallopavo). In addition to standard
morphological methods, the alizarin red S and potassium
pyroantimonate methods were employed for localization
of calcium at the light and electron microscopy level. In
light microscopy, calcified concretions with diameters
from 300 μm to 2 mm and quantities from 3 to 6 per
gland were observed in all the examined pineals. They
were stained red with alizarin S and showed the presence
of collagen in Mallory's staining. Two types of cells
were noted inside the concretion: polygonal and
elongated ones. Using electron microscopy, three parts
were distinguished within the calcification area. The
peripheral part contained densely packed collagen
fibrils, some elongated cells and numerous
pyroantimonate precipitates demonstrating the presence
of calcium ions. In the intermediate part, the fibrils were
covered by almost continuous sheets of pyroantimonate
precipitates and fused side by side. The central part
showed an appearance of calcified hard tissue and showed an appearance of calcified hard tissue and
contained some polygonal (osteocyte-like) cells. The
obtained data demonstrated that the formation of the
pineal concretions in the turkey is associated with the
mineralization of collagen. This process is completely
different from the mechanisms responsible for the
formation of the concretions in the mammalian pineal