So we have the internal cavity, the lumen of the seminphilus tubule and this red portion is the wall of the seminaries seminipherous tubule. Now, if we further zoom in on a portion of the wall, we get the following diagram. And this is the diagram that describes the process of spermatogenesis, how sperm cells are actually formed. So the red portion is the wall of the seminefriendly stewart. This is the basement membrane and this is the interstitulum. It's the interstitial space.