Ultrastructural Changes in the Parathyroid Gland of the Rabbit Following EDTA (Ethylenediamine Tetraacetic Acid) Injection

Abstract

Upon intraperitoneal injection of 4% EDTA solution to the rabbit, the author measured changes in serum calcium concentration after 30 minutes,1 hour,3 hours,6 hours,12 hours,24 hours and 48 hours respectively, and at the same time observed ultrastructural changes in the parathyroid gland with an electron microscope, thus obtained the following results.
1) Serum calcium concentration was rapidly lowered immediately after administration of EDTA, reaching the lowest value in 30 minutes after injection, then gradually rose to the normal value in 6 to 12 hours after administration.
2) In 30 minutes and 1 hour after administration of EDTA an aspect of secretory granules accumulated to the plasma membrane was observed.
3) Accumulation of secretory granules to the plasma membrane means an aspect indicating release of secretion. There were granules of low electron density and vacuoles both with almost the same size as secretory granules together with the mature secretory granules. It can be considered as an aspect indicating diacrine secretion.
4) An aspect of emiocytosis shown in the parathyroid gland of the normal rabbit could not be seen.
5) In 6 hours to 24 hours after administration of EDTA an increase of well-developed granular endoplasmic reticula, ribosomes and mitochondria was indicating that protein synthesis was actively functioning, however, in the Golgi apparatus no active formation of secretory granule was seen.