Periodization of the early postnatal development in the rat with particular attention to the weaning period
Related Experiment Video
Updated: May 20, 2026
Neurodevelopmental Reflex Testing in Neonatal Rat Pups
Published on: April 24, 2017
1Centre for Cardiovascular Research, Prague, Czech Republic. iostadal@biomed.cas.cz
Insights
The early postnatal period in rats shows critical developmental windows. Understanding these sensitive stages is crucial for predicting how interventions affect growth and development.
Area of Science:
- Developmental biology
- Comparative physiology
- Neonatal physiology
Background:
- The early postnatal period is a phase of high developmental plasticity in mammals.
- This period involves significant physiological transitions, including environmental adaptation and nutritional shifts.
- Specific time windows exist where insults or interventions can profoundly impact growth and development.
Purpose of the Study:
- To delineate the distinct phases of early postnatal development in rats.
- To identify critical time points within these phases that are sensitive to external influences.
- To emphasize the importance of precise developmental timing for understanding responses to pathogenetic stimuli.
Main Methods:
- Observation and documentation of key developmental milestones in rat pups.
- Chronological tracking of physiological and behavioral changes from birth to weaning.
- Correlation of developmental events with environmental and nutritional transitions.
Main Results:
- The presuckling period (first 6 hours) involves adaptation to air, temperature changes, and cessation of placental nutrition.
- The suckling period is characterized by milk consumption peaking around day 15, with weaning commencing around postnatal day 17.
- Physiological weaning concludes by postnatal day 28, with water intake initiated around day 19.
- The duration of these early postnatal periods is independent of body weight changes.
Conclusions:
- Precise knowledge of critical early postnatal developmental periods is essential.
- Understanding these sensitive windows aids in predicting and explaining reactions to pathogenetic stimuli in research and clinical settings.
- Developmental timing, rather than body weight, defines these crucial early life stages.
Abstract:
The early postnatal period is characterized by a great plasticity with critical windows in which any inadequate insult or intervention may be able to influence both positively and adversely postnatal growth and development. After birth the rat littermates enter the presuckling period (initial 6 hours terminated by the first nursing), characterized by transition from the amniotic fluid to the air, by the changes of the ambient temperature, by the termination of placental nutrition and by oxidative stress. After this stage the suckling period initiates and the littermates start to consume milk of their mothers. Comsumption of milk culminates on day 15, then decreases and terminates on postnatal day 28. The end of the suckling period and the onset of physiological weaning is determined by the moment when the youngs for the first time consume the solid food together with milk (postnatal day 17 in rats). On day 19 the first intake of drinking water occurs. The weaning period terminates by the last consumption of maternal milk - on postnatal day 28. It is necessary to stress that the duration of early postnatal periods is independent of the changes of body weight. The precise knowledge of individual ontogenetic periods critical for further development is crucial for the prediction and explanation of reactions to various pathogenetic stimuli both under experimental conditions and in clinical medicine.
