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Extrapituitary beta TSH and GH in early chick embryos
1Department of Physiology, and Perinatal Research Center, University of Alberta, 7-41 Medical Sciences Building, Edmonton, Alberta T6G 2H7, Canada.
Molecular and Cellular Endocrinology
|December 12, 2001
Summary
This study reveals that growth hormone (GH) and thyrotropin (beta TSH) are present in various tissues of early chick embryos before pituitary development. These hormones show distinct distributions in both neural and non-neural tissues, indicating early differentiation.
Area of Science:
- Developmental biology
- Endocrinology
- Cell biology
Background:
- Somatotropes and thyrotropes share a common lineage and depend on the Pit-1 transcription factor.
- Extrapituitary growth hormone (GH)-immunoreactive cells exist in peripheral tissues before pituitary differentiation.
Purpose of the Study:
- To investigate the presence and distribution of GH- and thyrotropin (beta TSH)-immunoreactivity in early chick embryos (embryonic day 7).
Main Methods:
- Immunohistochemical analysis of embryonic chick tissues at embryonic day 7.
- Utilized antisera against GH and beta TSH.
- Included control sections with preabsorbed antisera and pre-immune serum.
Main Results:
- GH-immunoreactivity was widespread in neural tissues (diencephalon, mesencephalon, ganglia, nerves) and spinal cord.
- beta TSH-immunoreactivity was found in ependymal cells, otic vesicle lining, epidermal cells, bronchial ducts, and pleural/pericardial cavities.
- Both GH and beta TSH were present in the crop and liver hepatocytes, but in distinct cell populations.
- Rathke's pouch (primordial pituitary) showed no GH or beta TSH staining at this stage.
Conclusions:
- Demonstrates the presence of beta TSH-immunoreactivity in extra-pituitary tissues of the embryonic chick prior to pituitary thyrotrope differentiation.
- Highlights the differential localization of GH- and beta TSH-producing cells within embryonic tissues.