1. Stories from the womb : investigating the relationship between joint shape emergence and mechanical stimulation in the murine embryo
- Author
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Sotiriou, Paraskevi (Vivien) and Nowlan, Niamh
- Abstract
Embryonic movements play an important role in joint development. Multiple animal model studies on embryos have shown that absent or abnormal musculature affect aspects of skeletal development, such as joint shape formation, joint cavitation and mineralisation. However, joint morphogenesis is the least researched aspect of joint development. In this doctoral dissertation, embryonic mouse forelimbs and hindlimbs at developmental stage (Theiler Stage) TS23 with normal, reduced, or absent muscle, and embryonic forelimbs and hindlimbs at TS24 and TS27 with normal or absent muscle were imaged in three dimensions. Virtual segmentation of skeletal rudiments and rigid image registration to reliably align rudiments with each other were performed, enabling repeatable assessment and measurement of joint shape differences. The shoulder, elbow, hip and knee joint shapes between normal, reduced muscle and absent muscle groups at TS23 were assessed. So were the differences in joint shape and mineralisation between normal and absent muscle embryos at TS24 and TS27. Cavitation in normal and muscleless-limb joints at TS24 and TS27 was also studied. It was shown that joint shapes are differentially affected by reduced or absent skeletal muscle with the elbow joint being the most affected. Surprisingly, reduced muscle often affected joint shape more than absent muscle, highlighting a complex interplay between muscle mass and joint morphogenesis. Counter intuitively, it was found that - as development progressed - when skeletal muscle was absent, different joints had recovered their shapes at different degrees. Hindlimb joints had completely recovered and the proportion of mineralisation of the muscleless-limb rudiments was similar to that of the same stage control rudiments at TS27. Uncavitated muscleless-limb joints at TS24 had not cavitated much or at all at TS27. These findings uncover complex interactions between skeletal development and muscle contractions and are relevant to human developmental disorders of the skeleton implicating abnormal fetal movements.
- Published
- 2021
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