Final answer:
Pluripotent stem cells can develop into any human cell type but cannot form a complete fetus, originating from the inner cell mass of the blastocyst stage after fertilization.
Step-by-step explanation:
The cells you are asking about, present several days after fertilization and can develop into any cell type but cannot become a fetus, are called pluripotent stem cells. These cells originate from the totipotent cells of the inner cell mass within the blastocyst, which is formed approximately 3 days after fertilization. While totipotent stem cells have the ability to develop into any cell type, including a whole organism, pluripotent stem cells can differentiate into any cell type of the human body but are not capable of developing into a full organism. Later, these pluripotent cells diversify further into multipotent cells, which can give rise to cells of a particular cell lineage or family.