How old are rat pups when their eyes open? - briefly
Rat pups typically open their eyes between post‑natal days 12 and 15, most commonly around day 14. This developmental milestone marks the transition to visual perception.
How old are rat pups when their eyes open? - in detail
Rat pups are born with their eyelids sealed. The first visible opening of the eyes occurs between the 10th and 14th post‑natal day (P10–P14). The exact day varies with strain, litter size, and rearing conditions; for example, Sprague‑Dawley rats typically open eyes at P12, while Wistar rats may do so at P11.
Key points of the ocular development timeline:
- P0–P3: eyelids remain fused; corneal epithelium begins differentiation.
- P4–P6: formation of the lacrimal gland and tear film initiates.
- P7–P9: retinal ganglion cells mature; spontaneous retinal waves are observed.
- P10–P14: eyelid separation; light exposure triggers rapid synaptic refinement in the visual cortex.
- P15 onward: visual acuity improves; pups respond to moving objects and begin orientation behaviors.
Factors influencing the timing include ambient temperature, humidity, and maternal care. Premature birth or hypoxic events can delay opening, while enriched environments may accelerate it slightly. After the eyes open, pups rely on visual cues for navigation, social interaction, and foraging, marking a transition from primarily tactile and olfactory guidance to multimodal sensory integration.