Growth of the laboratory mouse

Area of Science:

• Animal Science
• Genetics
• Developmental Biology

Background:

• Understanding genetic influences on body size and growth is crucial in animal models.
• Selection for large body size in mice has led to distinct lines with varying growth patterns.
• Comparative studies across different mouse lines reveal insights into developmental trajectories.

Purpose of the Study:

• To compare body weight and tail length growth patterns in four distinct mouse lines.
• To analyze body weight variability and its relationship with selection history.
• To investigate the correlation between growth inflection points and reproductive development.

Main Methods:

• Longitudinal monitoring of body weight and tail length from birth to 96 days in four mouse lines (C57BL/6J, J, GR, FR).
• Statistical analysis of mean body weights, tail lengths, and variance over time.
• Observation of age at vaginal opening in relation to growth inflection points.

Main Results:

• Lines GR and FR exhibited significantly higher mean body weights and plateaued growth compared to C57BL/6J and J lines.
• Body weight variability was lowest in C57BL/6J and J, intermediate in FR, and highest in GR.
• Tail length differences were observed, with GR exceeding FR.
• Age at vaginal opening coincided with the inflection point of body weight growth, occurring slightly earlier in females.

Conclusions:

• Mouse lines selected for large body size (GR, FR) demonstrate distinct growth dynamics and increased weight variability.
• Growth patterns and developmental milestones like vaginal opening are line-specific.
• These findings contribute to understanding the genetic architecture of growth and development in mammals.