A dysmorphic mouse model reveals developmental interactions of chondrocranium and dermatocranium

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Abstract

The cranial endo- and dermal skeletons, which comprise the vertebrate skull, evolved independently over 470 million years ago and form separately during embryogenesis. In mammals, much of the cartilaginous chondrocranium is transient, undergoing endochondral ossification or disappearing, so its role in skull morphogenesis is not well studied and it remains an enigmatic structure. We provide complete three-dimensional (3D) reconstructions of the laboratory mouse chondrocranium from embryonic day 13.5 through 17.5 using a novel methodology of uncertainty-guided segmentation of phosphotungstic enhanced 3D microcomputed tomography images with sparse annotation. We evaluate the embryonic mouse chondrocranium and dermatocranium in 3D and delineate the effects of a Fgfr2 variant on embryonic chondrocranial cartilages and on their association with forming dermal bones using the Fgfr2c^C342Y/+ Crouzon syndrome mouse. We show that the dermatocranium develops outside of and in shapes that conform to the chondrocranium. Results reveal direct effects of the Fgfr2 variant on embryonic cartilage, on chondrocranium morphology, and on the association between chondrocranium and dermatocranium development. Histologically we observe a trend of relatively more chondrocytes, larger chondrocytes, and/or more matrix in the Fgfr2c^C342Y/+ embryos at all timepoints before the chondrocranium begins to disintegrate at E16.5. The chondrocrania and forming dermatocrania of Fgfr2c^C342Y/+ embryos are relatively large, but a contrasting trend begins at E16.5 and continues into early postnatal (P0 and P2) timepoints, with the skulls of older Fgfr2c^C342Y/+ mice reduced in most dimensions compared to Fgfr2c^+/+ littermates. Our findings have implications for the study and treatment of human craniofacial disease, for understanding the impact of chondrocranial morphology on skull growth, and potentially on the evolution of skull morphology.

Data availability

Due to the large size of the majority of these data, data have been made available through Penn State University Libraries ScholarSphere repository at DOI 10.26207/qgke-r185 and include: bone micro-CT images, PTA-e micro-CT images, 3D reconstruction examples of the chondrocrania of one unaffected (Fgfr2c+/+) and one affected (Fgfr2cC342Y/+) at E13.5, E14.5, E15.5, E16.5, and E17.5, bone volumes, histological images, histomorphometric data, 3D landmark coordinate data, correlation matrices estimated by MIBoot used in MI analyses, PCA output, and suture scores. Information on how to download the WinEDMA programs can be found at https://getahead.la.psu.edu/resources/edma and the EDMAinR programs are available on github (https://github.com/psolymos/EDMAinR). Code for automatic chondrocranium segmentation with very sparse annotation via uncertainty-guided self-training is available through https://github.com/ndcse-medical/CartSeg_UGST. PTA-e staining protocols for various embryonic ages of mice are available: https://doi.org/10.1002/dvdy.136

The following data sets were generated

(2022) A dysmorphic mouse model reveals developmental interactions of chondrocranium and dermatocranium
The Pennsylvania State University ScholarSphere doi:10.26207/qgke-r185.

https://scholarsphere.psu.edu/resources/5ae72c36-d31a-435d-9cfb-5b3311656dd7

Article and author information

Author details

Susan M Motch Perrine

Department of Anthropology, The Pennsylvania State University, University Park, United States

For correspondence
qzk2@psu.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-3412-221X
M Kathleen Pitirri

Department of Anthropology, The Pennsylvania State University, University Park, United States

Competing interests
The authors declare that no competing interests exist.
Emily L Durham

Department of Anthropology, The Pennsylvania State University, University Park, United States

Competing interests
The authors declare that no competing interests exist.
Mizuho Kawasaki

Department of Anthropology, The Pennsylvania State University, University Park, United States

Competing interests
The authors declare that no competing interests exist.
Hao Zheng

Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9790-7607
Danny Z Chen

Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, United States

Competing interests
The authors declare that no competing interests exist.
Kazuhiko Kawasaki

Department of Anthropology, Pennsylvania State University, University Park, United States

Competing interests
The authors declare that no competing interests exist.
Joan T Richtsmeier

Department of Anthropology, Pennsylvania State University, University Park, United States

For correspondence
jta10@psu.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-0239-5822

Funding

National Institute of Dental and Craniofacial Research (R01DE027677)

Joan T Richtsmeier

Eunice Kennedy Shriver National Institute of Child Health and Human Development (P01HD078233)

Joan T Richtsmeier

National Institute of Dental and Craniofacial Research (R01 DE031439)

Joan T Richtsmeier

National Science Foundation (CCF-1617735)

Danny Z Chen

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols (#446558) of the Pennsylvania State University.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.