壁细胞

The sperm originate in gonial cells (spermatogonia) in the walls of seminiferous tubules.

精子产生于输精管壁的性母细胞（精原细胞）。

Here PMN's that are marginated along the venule wall (arrow) are squeezing through the basement membrane (the process of diapedesis) and spilling out into extravascular space.

图示边集于小静脉壁的中性粒细胞（箭头所示）正出基底膜（渗出），游走到血管外。