Medycyna Wet. 64 (6), 764-769, 2008
Magdalena Prusik, Bogdan Lewczuk
Structure of the avian pineal gland
The morphology of the avian pineal glands shows large interspecies variability. Considering the anatomic structure, six types of the pineal organs (I-VI) are distinguished in birds. They differ in the proportion between the distal and proximal parts of the gland as well as in the attachment to the intercommisural region. According to the histological structure, the avian pineal glands are classified into three types: the saccular, tubulo-follicular and solid type. The pineal parenchyma consists of pinealocytes, supporting cells and neurons. Among pinealocytes there are receptor pinealocytes (predominant in the saccular pineals), rudimentary-receptor pinealocytes (predominant in the tubulo-follicular organs) and secretory pinealocytes (most numerous in pineals of the solid type). The population of supporting cells consists of ependymal-like and astrocyte-like cells. Neurons are represented by afferent ganglion cells, present mainly in the saccular pineals. The pineals of tubulo-follicular and solid types possess well developed sympathetic innervation.
Keywords: pineal gland, birds, pinealocytes, morphology