Review of growth plate closure compared with age at sexual maturity and lifespan in laboratory animals.
Level 5 - mechanism / opinion, no new human data
Comparative review and synthesis of animal and human physiological baseline parameters across historical literature.
What was done
The authors conducted a literature review of MEDLINE and other databases covering 1966 to March 1999 to evaluate the timing of growth plate (epiphyseal) closure relative to sexual maturity and lifespan. Data were gathered across species, including mice, rats, rabbits, dogs, cats, sheep, cows, horses, nonhuman primates, and humans. Three comparative ratios were calculated: 1) age at growth plate closure to average lifespan, 2) age at growth plate closure to age at sexual maturity, and 3) age at sexual maturity to average lifespan.
What was found
The ratio of age at growth plate closure to average lifespan was 22 to 35 in rats, which overlapped with humans (17 to 25), whereas other nonhuman species had lower ratios ranging from 4 to 17. The ratio of age at growth plate closure to age at sexual maturity was 5 to 6 in rats, which was larger than in any other species. The ratio of age at sexual maturity to average lifespan was highest in humans and nonhuman primates (13 to 14).
Why it matters
Rats are widely used in musculoskeletal research, but their growth plates remain open and bone growth continues through a large portion of their lifespan long after sexual maturity, unlike most other laboratory animals. Understanding these interspecies physiological disparities is essential when selecting animal models and interpreting bone growth and skeletal maturity data.
Limits
The abstract does not report the total number of primary studies reviewed, sample sizes within those studies, or statistical variance/confidence intervals for the derived ratios. Potential heterogeneity in measurement techniques across historical literature was not detailed in the abstract.
Cited by
- supports Unlike humans whose growth plateaus in early adulthood, rodents continue to grow throughout the course of their life.