Human Fetus at 21 Weeks in the Womb (Brown Skin)

Description

A fetus of approximately 21 weeks gestation floats in amniotic fluid inside the translucent amniotic sac, seen from the left side with the trunk in flexion and the limbs drawn toward the midline. The head remains large in proportion to the body, the skull smoothly rounded with the eyelids still fused, the external ear now clearly modelled against the scalp, and one hand raised near the mouth. The lower limbs are flexed at hip and knee, the plantar surface of one foot turned toward the viewer, and the umbilicus is visible on the anterior abdominal wall where the coiled umbilical cord emerges. The cord, with its paired arteries and single vein suggested by the twisted vessels, sweeps across the fetal abdomen toward the placental disc seated on the vascular uterine wall in the background. Week 21 sits within the mid-second-trimester window used for detailed anomaly and growth ultrasound, when biometry such as biparietal diameter, head and abdominal circumference and femur length is measured and fetal anatomy is systematically surveyed. Depicting the sac, fluid volume, cord insertion and placental site together supports discussion of amniotic fluid assessment, cord coiling and placental localisation, all of which are documented at this stage. Recognisable behaviours of this period, including hand-to-mouth movement and progressive flexor tone, are relevant for teaching normal neurobehavioural development and for reassuring parents about perceived fetal activity. Suited to obstetric and midwifery teaching sequences that track a single pregnancy week by week, embryology and developmental anatomy lectures, and antenatal class or clinic material explaining what the mid-pregnancy scan shows. It also serves publishers producing pregnancy guides, prenatal apps and journal or textbook figures requiring a consistent, realistic depiction of intrauterine anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.