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Updated: Aug 15, 2026
Chicken Recombinant Limbs Assay to Understand Morphogenesis, Patterning, and Early Steps in Cell Differentiation
Published on: January 12, 2022
Limb movements during embryonic development in the chick: evidence for a continuum in limb motor control antecedent
Nina S Bradley1, Dhara Solanki, Dawn Zhao
1Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, 90089, USA. nbradley@usc.edu
Insights
Embryonic chick limb movements show coordinated patterns from embryonic day 9 to 18, suggesting a developmental continuum for locomotion. This research provides insights into early motor control and its implications for prenatal development.
Area of Science:
- Developmental biology
- Neuroscience
- Biomechanical engineering
Background:
- Advancements in fetal imaging highlight the importance of understanding embryonic motor behavior.
- The chick embryo is a valuable model for studying embryogenesis and motor development.
- Previous research has not fully established if embryonic motility is part of a continuous developmental pathway for posthatching behaviors.
Purpose of the Study:
- To investigate the kinematics and electromyography (EMG) of spontaneous limb movements in chick embryos.
- To determine if coordinated motor patterns observed in embryos represent a developmental continuum for locomotion.
- To describe the emergence of specific limb movement frequencies and interlimb coordination patterns.
Main Methods:
- Kinematic analysis and synchronized electromyography (EMG) were used to study limb movements in chick embryos at embryonic days 9, 12, 15, and 18.
- Analysis focused on knee and ankle excursions, as well as EMG activity during spontaneous movements.
- Interlimb coordination patterns were assessed across different developmental stages.
Main Results:
- Coordinated kinematic and/or EMG patterns were present at all studied embryonic time points.
- Distinct in-phase and out-of-phase coordination patterns emerged for knee and ankle movements by embryonic days 15-18.
- A developmental shift from in-phase to out-of-phase interlimb coordination was observed between embryonic days 9 and 18, with limb movements occurring at 2-10 Hz.
- EMG patterns did not fully explain out-of-phase movements, suggesting biomechanical factors are crucial.
Conclusions:
- Coordinated limb movements in chick embryos persist throughout development, supporting their role in a continuum for locomotion.
- The observed limb movement patterns align with the half-center model of locomotor pattern generation.
- The establishment of these patterns by embryonic day 9 may indicate a critical developmental phase for motor control, potentially influencing vulnerability to prenatal factors.
Abstract:
New imaging technologies are revealing ever-greater details of motor behavior in fetuses for clinical diagnosis and treatment. Understanding the form, mechanisms, and significance of fetal behavior will maximize imaging applications. The chick is readily available for experimentation throughout embryogenesis, making it an excellent model for this purpose. Yet in 40 yr since Hamburger and colleagues described chick embryonic behavior, we have not determined if motility belongs to a developmental continuum fundamental to posthatching behavior. This study examined kinematics and synchronized electromyography (EMG) during spontaneous limb movements in chicks at four time points between embryonic days (E) 9-18. We report that coordinated kinematic and/or EMG patterns were expressed at each time point. Variability observed in knee and ankle excursions at E15-E18 sorted into distinct in-phase and out-of-phase patterns. EMG patterns did not directly account for out-of-phase patterns, indicating study of movement biomechanics will be critical to fully understand motor control in the embryo. We also provide the first descriptions of 2- to 10-Hz limb movements emerging E15-E18 and a shift from in-phase to out-of-phase interlimb coordination E9-E18. Our findings revealed that coordinated limb movements persist across development and suggest they belong to a developmental continuum for locomotion. Limb patterns were consistent with the half center model for a locomotor pattern generator. Achievement of these patterns by E9 may thus indicate the embryo has completed a critical phase beyond which developmental progression may be less vulnerable to experimental perturbations or prenatal events.
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