Parathyroid gland of the freshwater snake Natrix piscator Schneider

The structure and function of the parathyroid glands of freshwater snake, Natrix piscator, were studied. N. piscator has two pairs of parathyroid glands which are composed of cell cords of typical endocrine appearance, and follicles are absent. Parathyroidectomy was followed by significant (P less than 0.001) hypocalcemia and hyperphosphatemia throughout the 5th week of experimental period. Following parathyroidectomy, calcium and phosphate concentrations in bone were significantly (P less than 0.05) increased after 5 weeks; however, these values in muscle were not significantly changed. Tetany was also observed in parathyroidectomized snakes. Histological structure and function of the glands do not appear to vary seasonally. Administration of parathyroid gland extract of this ophidian reptile into rats caused significant (P less than 0.05) elevation of serum calcium.