Cytochemical demonstration of lysosomes in the chicken pineal gland: changes induced by light-dark cycle.

Light and electron microscopic demonstrations for acid phosphatase (AcPase) activity in the chicken pineal gland were studied with special reference to the changes induced by the light-dark cycle. AcPase-positive lysosomes and Golgi cisternae and vesicles located in the pinealocyte in the light period are well developed and more numerous than in the dark period. In a few cases, a type of lysosome wrapping mechanism is present in the pinealocyte during the light period. Therefore, the lysosomes in the chicken pinealocyte appear active during the light period. In addition, the lysosomes may have functional relationships with the lipid-like inclusions seen in the dark period.