Attaching organic fibers to mineral: The case of the avian eggshell

McGill University researchers have published a study that reveals new ultrastructural details about the avian eggshell and its interior fibrous membrane.  Using advanced imaging techniques, they reveal how calcite mineral interfaces with a fibrous membrane.  In chicken eggshells, the authors reveal a reciprocal anchorage system at both micro- and nanoscale levels. This interaction in eggshells is part of a highly successful reproduction strategy used by birds, where whole fibers of a membrane embed into the mineral of the shell at the microscale, and then fine mineral projections ('nanospikes') penetrate into the fiber surface at the nanoscale to 'nail' it in place. This dual-scale anchorage increases the surface area for robust membrane attachment, essential for avian embryonic development and hatching. Loss of the attachment during egg incubation/brooding is lethal to the growing embryonic chick.  In both avian and non-avian reptile eggshells, these hierarchical and multiscale arrangements contribute to successful species reproduction outcomes, and they provide insights into biomineralization processes.

According to corresponding author Prof. Marc D. McKee, “Essential to our structural biology imaging work is the use of Dragonfly 3D World.  It is a 'workhorse' tool for all of us, integrated into essentially all of our studies. Working closely with Professor Natalie Reznikov and her research team, also at McGill University, we now delve deeply into the 3D world and extract new and useful information both in terms of imagery and quantifiable features. This in turn allows us to answer important biological questions in the field of biomineralization."

Video Presentation

Publication

Buss, D.J., Reznikov, N., and McKee, M.D. (2023). Attaching organic fibers to mineral: The case of the avian eggshell. iScience, 26(12).  https://doi.org/10.1016/j.isci.2023.108425

Research Center

McGill University, Faculty of Dental Medicine and Oral Health Sciences (https://www.mcgill.ca/dentistry/)

McGill University, Deparment of Anatomy and Cell Biology (https://www.mcgill.ca/anatomy/)

McGill University, Department of Bioengineering (https://www.mcgill.ca/bioengineering/)

Keywords: Eggshell membrane, Biomineralization, Material Science, Calcite mineral, Avian eggshell, Deep learning-based segmentation

Dragonfly. Mc Kee Publication Spotlight
Summary of the attachment of chicken eggshell to its underlying fibrous membrane. Fibers are incorporated into the shell mineral (calcite), and reciprocally, nanospikes of mineral penetrate into the fibers.
Dragonfly. Mc Kee Publication Spotlight
Chicken eggshell membrane fiber thickness maps by submicrometer micro-computed tomography, and fiber orientation maps by FIB-SEM.
Dragonfly. Mc Kee Publication Spotlight
Chicken eggshell membrane fiber mantle and core morphologies assessed in 2D (block face electron imaging) and in 3D (FIB-SEM tomography).
Dragonfly. Mc Kee Publication Spotlight
Attachment of interdigitated eggshell membrane fibers to the shell across the microscale in the chicken egg: there is ubiquitous and progressive embedding of fibers within the mammillary structures of the innermost shell.