Ultrastructure of the parathyroid gland of the quail, Coturnix coturnix japonica.

Electron microscopic studies were made of the parathyroid gland of quail aged 4 to 12 months. Most parenchymal cells consisted of chief cells. Sometimes, cells having numerous microfilaments, scant granular endoplasmic reticulum, a few mitochondria, a small Golgi apparatus, and long cell processes that extended between contiguous cells were located on a basal lamina. These cells may serve as supporting cells rather than as secreting cells. Numerous free ribosomes, abundant mitochondria, a well-developed granular endoplasmic reticulum and Golgi apparatus, many prosecretory granules and lysosomes, and a few mature secretory granules were characteristic of the chief cells. The cisternae of the Golgi apparatus were arranged in circular and serpiginous profiles in some chief cells. Secretory granules were distributed randomly throughout the cytoplasm and near the plasma membrane. Some cisternae of the granular endoplasmic reticulum occurred in close proximity to mitochondria. Morphological evidence for the synthetic and secretory activities of the chief cells suggested an active parathyroid function.