By the end of the sixth week of pregnancy, the fetal skeleton begins to form as cartilage spreads throughout the fetus. This marks a crucial transition from the prior mudghah or "lump of flesh" stage, where the fetus lacked human features, into the "bone" phase, during which skeletal bones start to develop. This skeletal framework provides the foundation for a recognizable human form, transitioning from a simple lump to a more defined structure. By the seventh week, the fetus has the basic outlines of human features, including limbs, which give the fetus a distinct appearance. In describing this development, the Qur’an states:
then We developed the drop into a clinging clot, then developed the clot into a lump ˹of flesh˺, then developed the lump into bones, then clothed the bones with flesh, then We brought it into being as a new creation. So Blessed is Allah, the Best of Creators.23:14
This verse aligns with the observed stages of fetal development, where the skeleton forms before muscles and flesh surround it, giving the fetus its human shape. The quick succession of events—forming cartilage, then bones, then muscles—is emphasized in the Arabic with a conjunction that implies rapid progression, reflecting the accelerated pace of these changes. Additionally, a narration from the Prophet Muhammad, peace be upon him, reported in Sahih Muslim, describes that at around forty days, the angel assigned to the fetus begins shaping it, forming features such as eyes, ears, skin, and bones. This transformation aligns with the sixth week in modern embryology, marking the transition from an unshaped mass of flesh to a structured form. By day 40 to day 45, the fetus's human characteristics begin to manifest, making this phase a significant demarcation line in its development. This emergence of a human shape after the bone structure forms is an indication of Divine knowledge within the Qur’an, corresponding accurately with discoveries that science only revealed centuries later.
