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Motility pattern and lung respiration of embryonic chicks under the influence of L-thyroxine and thiourea
Insights
Embryonic chick L-thyroxine and thiourea treatments alter hatching by affecting the onset of lung respiration. Sealing the air cell impacts hatching and respiration timing, suggesting pulmonary respiration
Area of Science:
- Developmental biology
- Avian physiology
- Embryology
Background:
- Embryonic chick development involves complex motor and respiratory changes.
- A period of reduced activity precedes hatching, during which pulmonary respiration begins.
- Hormonal and environmental factors can influence these critical developmental processes.
Purpose of the Study:
- To investigate the role of L-thyroxine and thiourea in embryonic chick hatching and respiration.
- To determine the impact of altered pulmonary respiration onset on the hatching process.
- To examine the influence of eggshell modifications on hatching and respiratory development.
Main Methods:
- Monitoring embryonic chick movements and respiration via air cell and eggshell pressure changes.
- Administering exogenous L-thyroxine and thiourea to developing embryos.
- Sealing the eggshell above the air cell to alter gas exchange and pressure dynamics.
Main Results:
- L-thyroxine accelerated hatching and the onset of reduced motility and lung respiration.
- Thiourea exhibited opposite effects, delaying hatching and altering motility/respiration patterns.
- Sealing the air cell normalized hatching and lung respiration onset times, despite earlier pipping.
Conclusions:
- The effects of L-thyroxine and thiourea on hatching are mediated by their influence on the timing of pulmonary respiration.
- Pulmonary respiration plays a crucial role in regulating the hatching process in embryonic chicks.
- Eggshell integrity and gas exchange dynamics are critical for coordinated hatching and respiratory development.
Abstract:
Pressure changes in the air cell and at the egg shell have been used to monitor respiratory and somatic movements of embryonic chicks. During the prehatching period a phase of reduced activity is observed. Pulmonary respiration is initiated during this phase. Exogenous L-thyroxine exerts an accelerating effect on the hatching process and on the onset of the phase of reduced motility and of lung respiration. In thiourea-treated embryos the opposite effects on the hatching process and on the motility and respiration pattern are registered. When, however, the egg shell above the air cell was sealed with glue, times of hatching and of the beginning of lung respiration were similar to those of controls, although pipping the egg shell occurred earlier than normal. It is suggested that the effects of L-thyroxine and thiourea on the hatching process are caused by a premature or delayed onset, respectively, of pulmonary respiration.