Coccyx is a curved, semi flexible lower end of the backbone (vertebral column) in humans, representing a vestigial tail. It is composed of three to five successively smaller caudal (coccygeal) vertebrae. The first is a relatively well-defined vertebra and connects with the sacrum; the last is represented by a small nodule of bone. The spinal cord ends above the coccyx. In early adulthood the coccygeal vertebrae fuse with each other; in later life the coccyx may fuse with the sacrum. Coccyx, the last bone in the vertebral column was mentioned in many Hadiths that this bone is the origin of humans and the seed from which they will be resurrected on the Day of Judgment and that this part doesn’t decay in the earth.

Stages of foetus formation:
When the sperm fecundate the ovule, foetus formation starts. The fecundated ovule or the zygote divides into 2 cells, and each cell divides into another 2 cells. Cells division and growth continue until the formation of the embryonic disk that contains 2 layers:

• External “Epiblast”: contains the cytotrophoblasts that fix the embryo in the uterus wall and enable its nutrition from the blood and the secretions of the glands of the uterus wall.

• Internal “Hypoblast”: From which the foetus is formed with the Will of Allah The Almighty. On the day15 the primitive streak appears in the dorsal aspect of the embryo with a pointed end called the primitive node.

The side on which the primitive streak appears is known as the back of the embryonic disc. From the primitive streak and node all the foetus tissues and organs are formed as follows:

• The Ectoderm: gives the skin and the central nervous system

• The Mesoderm: gives the digestive tract smooth muscles, the skeletal muscles, the circulation system, the heart, the bones the sexual and urinary systems (except the bladder), the subcutaneous tissues, the lymphatic system, the spleen and the cortex.

• The Endoderm: the linings of the digestive tract and the respiratory system, the organs related to the digestive tract (ex: liver and pancreas), the bladder, the thyroid gland, the hearing canal.
After that, the primitive streak and node become emaciated and reside in the sacral zone, in the last vertebrae, so that the coccyx is formed.

Foetus malformation is a proof that the coccyx contains the mother cells for all the human tissues:

After the creation and formation of the foetus from the primitive streak and the primitive node, those reside in the last vertebrae of the sacrum (the coccyx) and retain their characteristics. If those are motivated somehow, they start to grow similarly to the foetus growth and so give a tumour (Teratoma) that resembles a defective foetus with some organs fully formed (hands or feet with nails). Therefore the sacrum indeed contains the mother cells and what the prophet (PBUH) said about the Resurrection of humans from their coccyx on the Day of Judgment has been proved.

The conclusion: the coccyx contains the primitive streak and primitive node and those are able to grow giving the three layers that form the foetus: ectoderm, mesoderm and endoderm and so can give all the organs as the surgeon when opening the tumour previously mentioned found fully formed organs inside it like teeth, hair…

Humans can be then recreated from their coccyx that contains the primitive streak and node of the overall potential.

And so the coccyx can not get decayed:
Researchers found that foetus cells’ formation and organisation are exerted by the primitive streak and node and before their formation no cells’ differentiation could have taken place. One of the most famous researchers who proved this was the German scientist Hans Spemann.

After his experiments on the primitive streak and node he found that those organise the creation of the foetus and so he called them “The primary organiser”. He cut this part from one foetus and implanted it in another one in the primary embryonic stage (third and fourth week). This lead to the formation of a secondary foetus in the guest body due to the influence and organisation exerted by the surrounding guest’s cells on the implant.

The German scientist started his experiments on the amphibians by implanting the primary organiser in a second foetus, which led to the growth of a secondary embryo. The implantation of the cut primary organiser was in another foetus of the same age under the Epiblast layer and lead to the apparition of a secondary embryonic anlage.

In 1931, when Spemann crushed the primary organiser and implanted it again, the crushing did not affect the experiment as again, a secondary embryonic anlage grew.

In 1933, Spemann and other scientists conducted the same experiment but the primary organiser was boiled this time. A secondary embryonic anlage grew in spite of the boiling showing that the cells were not affected. In 1935, Spemann was awarded the Nobel Prize for his discovery of the Primary Organiser.

Narrated By Al-Amash: Abu Huraira said, "Allah's Apostle said, 'Between the two sounds of the trumpet, there will be forty." Somebody asked Abu Huraira, "Forty days?" But he refused to reply. Then he asked, "Forty months?" He refused to reply. Then he asked, "Forty years?" Again, he refused to reply. Abu Huraira added. "Then (after this period) Allah will send water from the sky and then the dead bodies will grow like vegetation grows, There is nothing of the human body that does not decay except one Bone; that is the little Bone at the end of the coccyx of which the human body will be recreated on the Day of Resurrection." (Shahi Bukhari)