Effects of experimental weaning upon the histochemical features of rat parathyroid gland in the puerperium.

Three types of protein granules, glycogen and ribonucleic acid (RNA) present in the cytoplasm of the rat parathyroid cells were chemocytologically examined at the various stages of experimental weaning, and based upon their morphology the cytophysiological significances of these cytoplasmic substances were discussed. Proteins and RNA were abundantly found in the parathyroid cells at the early stage of weaning but later decreased gradually in amount and reactivity with the progress of weaning. Cytoplasmic glycogen was found only in small amounts or absent at the early stage of weaning but gradually increased in amount up to the first half of the mid-weaning stage, followed by a gradual decrease thereafter to normal state. From these data, it is believed that in the early stage of weaning the secretory activity of the parathyroid cells is probably similar to that during lactation but later gradually falls to the normal state.