First of all, it does not end up at the same position exactly, that’s why we are so different and why are the anatomy books so big 😉 😀

Muscles, veins, organs and stuff end up into astonishingly similar positions in almost all healthy invidivduals if you take into account their extraordinary complexity. It is pretty amazing how similar body proportions and structures everybody has in the end. Even if you take a two-metre tall person and 1,5 m tall one, the proportions and locations of different body parts are very similar.

All this is due to multiple and extremely complex mechanisms. In the early stages it involves the cleavage of embryonal cell groups, development of different cell layers (germ layers) and formation of some crucial body structures such as the neural tube and the notochord in chordate animals. Until this and even bit further, all vertebrates follow a very identical developmental path.

How the eyes end up in the head and digits to the end of arms is dictated by such mechanisms as polar differentation, epiboly, delamination and ingression, as well as by specific apoptosis patterns and up-/downregulation of developmental gene regions.

One crucial feature is the formation of the cell layers ectoderm, endoterm and mesoterm, which eventually develop into organs and other body parts by very specific events of cleavage, splitting, folding and such.

So even though the cells do not end up excatly in the same positions in different persons, it is pretty astonishing how consistently this process happens in almost every individual.

Actually, I do 🙁 How did you know? 😕

Signaling I think is the most important. It is the expression of a gene that makes a specific protein that "signals" the next developmental process. It is all very complicated, thus a developmental biology textbook could show you what is known so far (which isn’t alot, as the explosion of noncoding RNA as regulators in the developmental process have now opened our eyes even more), but it is the signaling factors that I think is important. They are the directions of the developmental process, with the genes (coding and noncoding) in the DNA supplying the items for the directions.
Another thing that is amazing is the gradients of these signaling factors. How one cell will affect the cells that touch it, but no other cell. Creating lines of definition, which in turn will turn on/off a transcription factor that defines just those cells. Demarcation of one kind of cell to a different kind of cell in the same tissue/organ.
Funny that you mention aorta. The heart is looped in development, and in a asymmetrical way. Certain genes (Nodal is one at the very beginning that forms a left side gradient in the embryo) need to be turned on, and cilia (dyenin) needs to be expressed to "push" the tube a certain way.

yes its a fact that the human has not a exact cell positions.due to the this every human looks different so this not happen that the every human have a exact cell positioning.The cells can be grown to polarize directly on the device and then correctly placed by an integrated micro-positioning system in order to perform apical TIRF microscopy, without the need for an additional weight to force the apical membrane of the cells into the region of the evanescent wave.