20 weeks: Pyramidal tracts from cortex begin {pyramidal tract development}. Fetuses have REM sleep, indicating dreaming. Inner neocortex layers mature. Fetuses can have voluntary movements. Fetuses can move eyes, which aids eye development. Hair appears. Fetus is 250 millimeters. Malnutrition, narcotics, and emotional stress raise blood epinephrine level and cause hyperactivity.
4-Zoology-Development-Stages-Gestation
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Date Modified: 2022.0225