You are a doctor treating a patient who has recently experienced paralysis in his lower body. he asks you to give him more information about the use of adult stem cells and embryonic stem cells as possible treatment

you must use the word "pluripotent" and multipotent" and you list two advantages and two disadvantages of each

The laboratories have initiated Phase 1 clinical trials for the use of human pluripotent embryonic stem cells to treat paralyzed patients following spinal cord injury. The first step is to estimate the risks and tolerance of cell transplantation in a man. The fate of stem cells (multipotent or pluripotent) in the body is still poorly understood, and it is not excluded that uncontrolled cell multiplications occur, leading to the appearance of teratomas (tumor developed from pluripotent cells).

Advantages are:

* The safety of the cells also seems to be proven (in short term)

* Rats transplanted seven days after the injury had benefited from reactivation of myelinization of neurons by oligodendrocytes, attenuation of motor neuron loss and improvement of limb motor function.

The disadvantages are:

* Constraints of the ethical and religious order, it is necessary the consent and the approval of the donor and the recipient for the transplant to take place.

* The development of the technique is still new, there is a chance that side effects of the transplant appear years after the operation.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.