Postotic and preotic cranial neural crest cells differently contribute to thyroid development

Area of Science:

• Developmental Biology
• Endocrinology
• Neuroscience

Background:

• Thyroid gland morphogenesis involves several stages, including specification, budding, descent, bilobation, and folliculogenesis.
• The cranial neural crest (CNC) contributes to thyroid gland development, with the postotic CNC implicated in cardiovascular and other organ development.
• The precise roles of different CNC regions in thyroid bilobation remain unclear.

Purpose of the Study:

• To investigate the specific roles of preotic and postotic CNC in thyroid gland bilobation.
• To elucidate the contribution of CNC cells to thyroid tissue formation and morphogenesis.

Main Methods:

• Ablation of preotic and postotic CNC regions in chick embryos.
• Quail-to-chick chimeras to trace cell differentiation.
• Analysis of thyroid morphology and size at different developmental stages.
• Pharmacological inhibition of endothelin signaling pathways.

Main Results:

• Preotic CNC ablation resulted in unilateral thyroid lobes.
• Postotic CNC ablation led to single or absent thyroid lobes.
• Postotic CNC cells differentiated into thyroid connective tissues, while preotic CNC cells did not but encompassed the thyroid anlage.
• Endothelin signaling pathway disruption mimicked CNC ablation phenotypes, causing bilobation anomalies.

Conclusions:

• Both preotic and postotic CNC are essential for normal thyroid gland bilobation.
• Preotic CNC plays a role in surrounding and potentially guiding thyroid development, while postotic CNC contributes to its structural integrity.
• Endothelin signaling is implicated in CNC-mediated thyroid morphogenesis.