3 ms·
Because nails and hair are produced at a fixed site. The nail itself is dead cells and do not grow.
by huytersd 2y ago
Because nails and hair are produced at a fixed site. The nail itself is dead cells and do not grow.
- gumby 2y agoThat isn't the question (in a prior job I studied the physiology of the nail unit). Most cells don't normally have an orientation, so you'd think that thefollicle would push out a hair in some random direction, sometimes towards the outside world and sometimes in the direction of your bones. Obviously they don't (!) but the question is how? The nail is the same: the lunula emits these keratinocytes in only one direction; even more weirdly it's a planar structure.
- throwup238 2y ago> Obviously they don't (!) but the question is how? Don't cells "just" orient themselves using mechanotransduction [1] or am I missing something? That's a bit hand wavey but since cells don't form 3d structures in tissue themselves, they orient against the extracellular matrix using mechanotransduction and other growth factors. The development of multicellular life was essentially cells learning how to orient themselves into a digestive tract. [1] https://en.wikipedia.org/wiki/Mechanotransduction https://en.wikipedia.org/wiki/Mechanotransduction