RNAs are the direct products of genes, and these small RNAs can bind to other specific messenger RNA (mRNA) molecules and either increase or decrease their activity, for example by preventing an mRNA from producing a protein.
What causes stretch marks? Stretch marks are caused when the skin rapidly stretches as a result of sudden growth or weight gain. The stretching causes the middle layer of skin (dermis) to tear, allowing the deeper skin layers to show through, forming stretch marks. The dermis contains strong, inter-connected fibres that allow your skin to stretch as your body grows.
Stretch marks can be visible on body parts including the tummy, thighs, hips, breasts, upper arms, and lower back. The marks form in the middle layer of the skin; when there is a constant stretch, the layer tears, leaving stretch marks. This type of scarring happens when the skin cannot bounce back after a period of intense growth, be that due to pregnancy, weight gain, or during puberty.