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Paralysis and long bone growth in the chick: growth shape trajectories of the pelvic limb
J E Bertram1, L S Greenberg, T Miyake
1College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Insights
Embryonic bone growth is altered by paralysis. Paralyzed chick limb bones were shorter but stouter than normal, indicating a changed growth trajectory.
Area of Science:
- Developmental biology
- Comparative anatomy
- Biomechanics
Background:
- Limb development is a complex process involving coordinated cell growth and differentiation.
- Understanding bone growth trajectories is crucial for diagnosing and treating skeletal abnormalities.
Purpose of the Study:
- To investigate the impact of paralysis on the growth and shape of embryonic chick limb bones.
- To compare the growth trajectories of paralyzed and normal embryonic chick bones.
Main Methods:
- Chick embryos were incubated and paralyzed at 5 days.
- Femora, tibiotarsi, and phalanges were measured daily from day 6 to 16.
- Growth in length, width, and changes in bone shape were analyzed.
Main Results:
- Paralysis significantly affected bone growth, particularly the length of the first phalanx of digit three.
- Paralyzed long bones were shorter than control bones.
- Contrary to expectations, paralyzed bones were relatively more stout (wider) than control bones, indicating altered shape changes.
Conclusions:
- Embryonic paralysis disrupts normal bone growth patterns and alters bone shape.
- The study reveals a distinct growth trajectory for paralyzed bones compared to normal development.
- These findings have implications for understanding skeletal development under conditions of reduced mechanical loading.
Abstract:
Growth of chick embryonic femora, tibiotarsi and first phalanges of digit three were measured at one day intervals from day 6 through 16 of incubation. Normal controls were compared to embryos paralyzed at 5 days of incubation. Over the 10 day study period, length of the paralyzed femora, length and width of the paralyzed tibiotarsi and differences in length of the phalanges were observed. Growth in length of phalanx one of digit three was most affected by paralysis over this period. Changes in shape of these bones also occurred during growth. Normal long bones undergo changes in shape as differential growth in length and width occurs. Such changes in shape can be considered as the bone's normal growth "trajectory". Paralyzed bones displayed a different growth trajectory than normal bones. As expected, the long bones of paralyzed embryos were shorter than age-matched controls. Contrary to expectations, however, paralyzed long bones were relatively more stout than age-matched controls.