Immunocytological evidence for parathyroid hormone in human fetal parathyroid glands.

Immunostaining with antiserum to bovine parathyroid hormone (PTH) was used to delineate the immunoreactive PTH (iPTH)-containing cells of parathyroid glands from 1 anencephalic and 29 normal human fetuses. The antiserum (GPO 3) cross-reacted with human PTH and recognized the carboxyl-terminal fragments of the PTH molecule. No iPTH-containing cells were observed in the parathyroid glands of the 6 fetuses younger than 10 weeks, in spite of the fact that organized parathyroid glands were identified by histological methods. By contrast, iPTH-containing cells were observed in all fetuses older than 10 weeks of gestation, including the anencephalic fetus. All cells were immunoreactive either at the cellular periphery or as a more diffuse cytoplasmic staining around the nucleus. No immunoreactive cells were observed in the thyroid or thymic parenchyma. The specificity of the immunocytological reaction was tested by the usual procedures. Previous in vitro studies suggested that parathyroid function might be active at 12 weeks of gestation. Our data suggest that iPTH is synthetized by parathyroid glands as as early as 10 weeks of gestation and is also present in the anencephalic fetus. The physiological significance of the early presence of PTH within the fetal parathyroid glands remains to be established.

[Calcitonin-cells in the thyroid of the human fetus. Immunocytochemical study (author's transl)]. / Les cellules à calcitonine dans la thyroïde du foetus humain. Etude par immunocytochimie.

Calcitonin (CT)-cells were detected, by using an anti-human calcitonin serum (hCT), in the thyroid of the normal and anencephalic human fetuses. The first CT-cells were observed at 14 weeks of gestation. The CT-cells were at first isolated afterwards were appeared in parafollicular localization. The CT-cells were only observed in the middle of the upper or medium third or the lateral lobes, along the central axis of the lobes. No CT-cells were detected in the isthmic region or in the inferior third of the lobes. CT-cells were also seen in the thyroid of the anencephalic fetuses. The specificity of the immunocytological reaction was ascertained after incubation of anti-hCT serum with homologous or heterologous antigens: after incubation of the anti-hCT serum with hCT, the immunocytological reaction was disappeared, but no modification of the reaction was noted after incubation with somatostatin, T4 or parathormone. The CT appeared precociously in the thyroid of the human fetus and their localization was the same that in the older subjects.