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Linear growth in the rabbit is continuous, not saltatory
K O Klein1, P J Munson, J D Bacher
1Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
Endocrinology
|March 1, 1994
Summary
Human growth is not in sudden bursts but occurs continuously. This study challenges the saltatory growth hypothesis, finding continuous linear growth in mammals.
Area of Science:
- Human physiology
- Developmental biology
- Biophysics
Background:
- A recent hypothesis proposed human growth occurs in discrete saltatory bursts, alternating with periods of stasis.
- This saltatory growth model suggests a rapid on/off hormonal mechanism controlling growth plates.
Purpose of the Study:
- To test the saltatory growth hypothesis by examining mammalian growth patterns.
- To determine if linear growth is continuous or occurs in bursts.
Main Methods:
- Proximal tibial growth in rabbits was measured to assess daily growth velocity.
- Rabbit models allow for measurement accuracy over 15 times greater than in humans for daily growth rates.
- The frequency distribution of daily growth velocities was analyzed for patterns.
Main Results:
- Observed daily growth velocities in rabbits approximated a single Gaussian distribution.
- The data did not support a bimodal distribution predicted by the saltatory growth model.
- Continuous growth, rather than saltatory bursts, was indicated.
Conclusions:
- Linear growth in mammals, as studied in rabbits, is a continuous process.
- The findings refute the saltatory growth hypothesis in the most accurately studied mammalian system.
- Continuous growth implies a different regulatory mechanism than previously proposed for saltatory growth.