The Epithelial Egg Tooth of the Chicken Shares Protein Markers with the Embryonic Subperiderm and Feathers

Title (eng)
The Epithelial Egg Tooth of the Chicken Shares Protein Markers with the Embryonic Subperiderm and Feathers
Author
Attila Placido Sachslehner
Author
Julia Steinbinder
Author
Claudia Hess
Author
Veronika Mlitz
Author
Leopold Eckhart
Abstract (eng)
The epithelial egg tooth is used by birds to open the eggshell for hatching. This ectodermal structure consists of a multilayered periderm and a hard cornified portion, the caruncle or actual egg tooth. Here, we determined the protein composition of the egg tooth of the chicken and compared the proteins to markers of other epithelia identified in previous studies. The egg tooth and the upper beak of chicken embryos of Hamburger and Hamilton (HH) stage 44 were subjected to mass spectrometry-based proteomics. We found that scaffoldin, a marker of the embryonic periderm and the feather sheath, was enriched in the egg tooth relative to the beak. Likewise, Epidermal Differentiation protein containing DPCC Motifs (EDDM) and Epidermal Differentiation protein starting with a MTF motif and rich in Histidine (EDMTFH), which had previously been characterized as markers of the subperiderm on embryonic scutate scales and the barbs of feathers, were also enriched in the egg tooth. The expression of EDDM and EDMTFH was confirmed RT-PCR analysis. Our data suggest that the epithelial egg tooth is related to the subperiderm and feathers, a hypothesis with potentially important implications for the evolution of the avian integument.
Keywords (eng)
Skin AppendagesEgg ToothFeathersKeratinocytesDifferentiationCornificationKeratinPeridermHatchingBirds
Type (eng)
journal article
Language
[eng]
Persistent identifier
https://phaidra.vetmeduni.ac.at/o:5368
DOI
10.3390/jdb14010001
Is in series
Title (eng)
Journal of Developmental Biology
Volume
14
Issue
1
ISSN
2221-3759
Issued
2026
Number of pages
15
Publication
MDPI
Version type (eng)
version of record (published version)
Date issued
2026
Access rights (eng)
open access
License
CC BY 4.0 International
Rights statement (eng)
© 2025 by the authors