Related Experiment Videos
Diffusive resistance of avian eggshell pores.
Ø Tøien1, C V Paganelli, H Rahn
1Department of Physiology, State University of New York, Buffalo 14214.
Respiration Physiology
|December 1, 1988
Summary
Avian eggshell pores control gas diffusion, with calculated pore conductance significantly higher than previously estimated. This pore conductance appears independent of egg mass across various species.
Area of Science:
- Physiology
- Biophysics
- Avian Biology
Background:
- Gas diffusion through avian eggshells is crucial for embryonic development.
- The microscopic pores within the eggshell are the primary sites of gas exchange resistance.
Purpose of the Study:
- To calculate the resistance to water vapor diffusion of individual avian eggshell pores.
- To compare calculated pore conductance with previously measured shell conductance.
Main Methods:
- Utilized pore dimension measurements from published pore casts of 321 avian eggshells across 23 species.
- Calculated diffusive resistance using Fick's first law and a 100-segment pore model.
- Incorporated boundary layer resistances using Stefan's and Poiseuille's laws for convective resistance.
Main Results:
- Calculated average pore conductance (5.4 µg day⁻¹ Torr⁻¹) was approximately three times higher than previously estimated values (1.6 µg day⁻¹ Torr⁻¹).
- Aperture resistances constituted a small fraction of total pore resistance (<6.2%).
- Calculated and functional pore conductance were found to be independent of egg mass.
Conclusions:
- The resistance to gas diffusion is primarily determined by the pore structure itself.
- There is a significant discrepancy between calculated and functional pore conductance, requiring further investigation.
- Eggshell pore conductance is a consistent physiological trait across different avian egg sizes.