Gastrulation: The Blueprint of Life

Your transition from a flat disk to a complex human happened in a single, wild week.

This is week three of embryonic development, where a process called gastrulation turns you from two

boring layers into three vital ones. This triggers everything. A master structure called the notochord

forms, acting like a blueprint that tells your spinal cord and brain exactly where

to grow. At the same time, your heart tubes fuse and actually start beating around

day twenty-one. It even decides your left from your right. Without this week,

you would literally just be a microscopic puddle of cells.