Aims: 

The calcification is a well known phenomenon of the pineal gland in mammals and completely unknown in birds. In the present work we analyzed the pineal concretions in the turkey in relation to their internal composition.

Methods: 

The studies were performed on the pineals collected from 56-week-old domestic turkeys (Meleagris gallopavo). We employed standard morphological methods as well as the alizarin red S procedure and the potassium pyroantimonate method for localization of calcium at light and electron microscopy levels.

Results: 

In light microscopy the calcified concretions with diameters from 300 mm to 2 mm and in number from 3 to 6 were observed in the parenchyma of all examined pineals. The concretions were stained red with the alizarin S method and showed the presence of collagen fibers. In electron microscopy the concretions were composed mainly of the collagen fibers and calcium deposits. Their central part showed typical appearance of calcified hard tissue and contained some osteocyte-like cells.

Conclusion: 

The formation of the pineal concretions in turkey is a process associated with the mineralization of collagen fibers. It is completely different from the mechanism responsible for the formation of concretions in the mammalian pineal gland. The question arises if the process is typical for all birds or it is species specific.