May I know something about embryo development

[Hayat]

I want to know which one formed before the other in the embryo, the flesh or the bones ? And what is the scientific reference for the answer ?

[Darby]

Your terms are too vague to be answerable - what is "flesh" and what is "formed"?

Is some sort of differentiation the same as "formed," or does the structure need to be functional? Is the initial cartilaginous layout of the skeleton enough to be "bones forming," even though that tissue will be broken down and replaced?

[kanzure]

The embryonic limb starts with this mesenchymal core, and myocytes migrate from another location to the limb, so when we are talking about cartilage we are mainly talking about this undifferentiated mass of cells in what is known as the "progress zone." Coincidentially, to answer your question, the progress zone is directly beneath an ectodermal layer (the layer that generates the epidermis, nervous system, etc.)

Bones are developed from the process known as endochondral ossification, in which the cartilage is replaced by bone- starting from the diaphyses (centers) and spreading outward.

Sorry for the absence of links, the forum prevents it.

- Bryan