Thymus-Associated Parathyroid Hormone Has Two Cellular Origins with Distinct Endocrine and Immunological Functions
Figure 2
Incomplete separation of parathyroid and thymus organs results in extra-parathyroid PTH production.
Paraffin section in situ hybridization for Gcm2 (A) and Pth (A–E); sections were cut in the sagittal plane. In all figures, anterior is up, and dorsal is to the right. Ages of embryos are in the upper left corner of each panel. Probes used for in situ hybridization are in the lower right. (A) Wild-type embryos at E12 (I), E13 (II) and E18.5 (III) show the separation of parathyroid and thymus organs from the common primordium. The parathyroid/thymus common primordia in panels A–I are outlined. (B) Loss of both parathyroid gland and misplaced parathyroid cells in Gcm2−/− mutants. (C) Location of PTH-expressing cells that were close to or attached to the wild-type thymus. In panels A–C, embryos used were on C57BL/6J genetic background. (D–E) The aparathyroid phenotype caused by Gcm2 null mutation also happens in the 129S6 genetic background. (D) Section in situ hybridization for Pth in wild-type E18.5 129S6 embryos shows the primary parathyroid (arrow) and several misplaced parathyroid cells (arrowheads). (E) Analysis of Gcm2 null mutants shows the loss of all parathyroid cells on the 129S6 genetic background. In all panels, black arrows point to the parathyroid. White arrows point to the thymus domain. Arrowheads point to misplaced parathyroid cells. pt, parathyroid; th, thymus; tr, thyroid. Scale bars = 0.1 mm.