Mice are often studied in research due to their genetic similarities to humans and relatively short lifespans. Their development progresses through distinct life stages with unique biological and behavioral changes. Among these, the juvenile stage is a period of growth and maturation.
Defining the Juvenile Stage
The juvenile stage begins after weaning (around postnatal day (PND) 21) and extends to sexual maturity (between PND 30 and PND 40). This period involves rapid physical development, including continued growth and refined motor capabilities. By PND 21, juvenile mice have developed fur, open eyes, and can feed independently, no longer relying on their mother’s milk.
Their physical appearance becomes more defined, transitioning from smaller pups to a smaller adult-like form. It concludes with reproductive capability. This transition involves acquiring self-sufficiency in foraging and navigation.
Key Behavioral Traits
The juvenile stage is dynamic for behavioral development, marked by complex social interactions and exploratory drive. Juvenile mice exhibit playful and social behaviors. Rough-and-tumble play (wrestling, pinning, chasing) becomes prominent, peaking PND 28-35.
These playful interactions develop social competence and establish dominance hierarchies. Exploratory behavior increases as juvenile mice venture further from their nest, investigating novel objects and environments. This curiosity aids in learning about surroundings and identifying resources or threats.
Motor skills mature throughout the juvenile phase, improving coordination, agility, and balance. They become adept at climbing, running, and navigating complex terrains. Refinement of these physical abilities, combined with social and exploratory behaviors, prepares them for adult life and independent survival.
Role in Scientific Research
Studying juvenile mice provides insights into biological and behavioral development, making them a research model. Researchers utilize this stage to understand brain development. The juvenile period involves neural circuit refinement and synaptic pruning, helping understand how experiences shape the developing brain.
This period is relevant for modeling neurodevelopmental disorders, such as those affecting brain wiring or cognitive function. Studying juvenile mice allows exploration of genetic mutations or environmental factors on brain structure and function during sensitive development periods. Research on juvenile mice helps understand the long-term effects of early-life experiences (e.g., stress, nutritional deficiencies) on adult health and behavior. Insights from these studies inform our understanding of human development and the origins of neurological and psychiatric conditions.
References
“Developmental milestones of the mouse” – Mouse Phenome Database. https://phenome.jax.org/projects/MPD/developmental_milestones. [Accessed 2024-07-24].
“The social behaviors of laboratory mice” – PLOS One. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084022. [Accessed 2024-07-24].
“Exploratory behavior in mice” – Frontiers in Behavioral Neuroscience. https://www.frontiersin.org/articles/10.3389/fnbeh.2015.00030/full. [Accessed 2024-07-24].
“Mouse models of neurodevelopmental disorders” – Nature Reviews Neuroscience. https://www.nature.com/articles/nrn.2017.152. [Accessed 2024-07-24].
“Early life stress and brain development” – Trends in Neurosciences. https://www.cell.com/trends/neurosciences/fulltext/S0166-2236(16)30177-7. [Accessed 2024-07-24].