Collagen is produced in the human body until natural aging occurs, whereas elastin is mainly produced during the fetal period. Collagen has the main property of providing structures with strength, whereas elastin will allow the structures which contain it to stretch and return to their initial form without damage
From what I know, collagen/elastin ratio as well as the collagen and elastin structures change with age [3,4,5,6]. The elasticity of the skin increases with atrophy of the collagen fiber bundles, the related flattening of the rete ridges, and the thickening of the dermal elastic fiber.
Rough endoplasmic reticulum contains ribosomes, while smooth endoplasmic reticulum does not contain ribosomes. The ribosomes are what give rough endoplasmic reticulum its characteristic "roughness."
