i think the texture in the open space is not intentional. The texture looks like the result of the clay or the glaze cracking on a surface level after the piece came out of the kiln.
If you zoom in, you'll see that the texture does not resemble blood vessels or skin, as the angles and lines are not so organic. Right about in the middle of the open space, there is even an almost rectangular shape formed by the cracks, very inorganic, and further supporting the idea that the texture of the open space is either smugate nor organic.