Endocrine - Parathyroid Development

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Introduction

Embryonic origins of the endocrine organs of the neck

The parathyroid gland appears in the adult as a pair of inferior and a pair of superior "bumps" on the beside the (dorsal) thyroid (hence the name, "para"). The embryonic origin of this gland is from the third and fourth pharyngeal pouches endoderm, and could also have ectoderm and neural crest contributions.

At 6 weeks a diverticulum elongates from the pouch, initially hollow and then solidifynig with cell proliferation.

Interestingly, the inferior parathyroid originates from the third pharyngeal pouch and the superior arises from the fourth pharyngeal pouch, the adult anatomical position is the opposite of the pharyngeal rostro-caudal order. This occurs due to the third pharyngeal pouch also giving rise to the thymus, the superior pair descend along with the thymus.

The fetal parathyroids appear functional as they respond to calcium levels. The fetal calcium levels also higher than maternal levels.

Endocrine Links: Introduction | BGD Lecture | Science Lecture | Lecture Movie | pineal | hypothalamus‎ | pituitary | thyroid | parathyroid | thymus | pancreas | adrenal | endocrine gonad‎ | endocrine placenta | other tissues | Stage 22 | endocrine abnormalities | Hormones | Category:Endocrine
Historic Embryology - Endocrine  
1903 Islets of Langerhans | 1903 Pig Adrenal | 1904 interstitial Cells | 1908 Pancreas Different Species | 1908 Pituitary | 1908 Pituitary histology | 1911 Rathke's pouch | 1912 Suprarenal Bodies | 1914 Suprarenal Organs | 1915 Pharynx | 1916 Thyroid | 1918 Rabbit Hypophysis | 1920 Adrenal | 1935 Mammalian Hypophysis | 1926 Human Hypophysis | 1927 Adrenal | 1927 Hypophyseal fossa | 1930 Adrenal | 1932 Pineal Gland and Cysts | 1935 Hypophysis | 1935 Pineal | 1937 Pineal | 1935 Parathyroid | 1940 Adrenal | 1941 Thyroid | 1950 Thyroid Parathyroid Thymus | 1957 Adrenal

| Lecture - Head Development |

Some Recent Findings

Human Embryo (week 6 - 8)[1]
  • Thymus-associated parathyroid hormone has two cellular origins with distinct endocrine and immunological functions[1] "In mammals, parathyroid hormone (PTH) is a key regulator of extracellular calcium and inorganic phosphorus homeostasis. Although the parathyroid glands were thought to be the only source of PTH, extra-parathyroid PTH production in the thymus, which shares a common origin with parathyroids during organogenesis, has been proposed to provide an auxiliary source of PTH, resulting in a higher than expected survival rate for aparathyroid Gcm2⁻/⁻ mutants. However, the developmental ontogeny and cellular identity of these "thymic" PTH-expressing cells is unknown. ...Our data show conclusively that the thymus does not serve as an auxiliary source of either serum PTH or parathyroid function. We further show that the normal process of parathyroid organogenesis in both mice and humans leads to the generation of multiple small parathyroid clusters in addition to the main parathyroid glands, that are the likely source of physiologically relevant "thymic PTH."" Endocrine - Thymus Development

Development Overview

Parathyroid primordia (week 6 GA)[1]
Adult parathyroid anatomy
  • Endoderm - third and fourth pharyngeal pouches, could also have ectoderm and neural crest
  • 3rd Pharyngeal Pouch - inferior parathyroid, initially descends with thymus
  • 4th Pharyngeal Pouch - superior parathyroid
  • Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation
  • Fetal parathyroids - respond to calcium levels, fetal calcium levels higher than maternal

Parathyroid Hormone

(PTH, parathormone or parathyrin) A polypeptide (84 amino acids) hormone which increases the concentration of calcium ions in the blood. Its actions oppose the hormone calcitonin from the thyroid gland parafollicular cells (C cells), which decrease calcium. Acts through the parathyroid hormone receptor in bone, kidney and gastrointestinal tract.

  • stimulate osteoclasts - degrade bone matrix, releasing calcium
  • increase calcium gastrointestinal tract absorption

Parathyroid Hormone-related Protein

(PTHrP) Originally identified in the clinical syndrome humoral hypercalcemia of malignancy. It's developmental role is that of a regulatory protein expressed during the formation of many organs.

  • mammary gland development - epithelial-mesenchymal interactions[2]
  • chondrocyte differentiation[3]

Abnormalities

Hyperparathyroidism

Postnatal

  • Postnatal adult ageing increased parathyroid hormone plasma levels are associated with cognitive decline and dementia.
  • Parathyroid carcinoma (cancer) is a rare malignancy, occurring with an incidence of 0.5 to 4% of all cases of primary hyperparathyroidism.

Adult Histology

References

  1. 1.0 1.1 1.2 <pubmed>21203493</pubmed> | PLoS Genet.
  2. <pubmed>10219904</pubmed>
  3. <pubmed>19076361</pubmed>


Reviews

  • The development of the parathyroid gland: from fish to human. Zajac JD, Danks JA. Curr Opin Nephrol Hypertens. 2008 Jul;17(4):353-6. Review. PMID: 18660669
  • Parathyroid development and the role of tubulin chaperone E. Parvari R, Diaz GA, Hershkovitz E. Horm Res. 2007;67(1):12-21. Epub 2006 Sep 27. Review. PMID: 17008776
  • Role of parathyroid hormone-related peptide and Indian hedgehog in skeletal development. Jüppner H. Pediatr Nephrol. 2000 Jul;14(7):606-11. Review. PMID: 10912527

Articles

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  • Parathyroid Development - All (3523) Review (768) Free Full Text (741)


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Terms

  • parathyroid hormone - (PTH, parathormone or parathyrin) A polypeptide (84 amino acids) hormone secreted by the parathyroid gland, which increases the concentration of calcium ions in the blood. Its actions oppose the hormone calcitonin from the thyroid gland parafollicular cells (C cells), which decrease calcium. Acts through the parathyroid hormone receptor located mainly in bone, kidney and gastrointestinal tract. Hormone dual role is to: stimulate osteoclasts in bone to degrade bone matrix releasing calcium; increase gastrointestinal tract absorption of calcium.


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Cite this page: Hill, M.A. (2024, March 28) Embryology Endocrine - Parathyroid Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_-_Parathyroid_Development

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G