The efferent ducts lead from the rete testis to the epididymis.
Sperm moving through them aren't yet motile.
Even though they're morphologically normal, the sperm's capacity for independent movement hasn't yet developed. The efferent ducts therefore have a ciliated epithelium to help propel the sperm through. This epithelium is of different height in different parts of the ducts, and so in cross section, as you see it here, it has a peculiar "scalloped" appearance.The cilia are mainly on the taller cells of this columnar epithelium. It's worth noting that these are true cilia, i.e., they have an axonemal core and are capable of movement.
The efferent ducts are derived from pre-existing structures in the
embryo, specifically from the drainage ducts of the
mesonephros, the "middle kidney." Not all of the mesonephric
ducts get used, however. Some of them never get connected to the
developing gonads and for the most part degenerate with the rest of
the mesonephros. But remnants may remain, and you can see some of
them in this image, alongside the "successful" ones that
metamorphosed into efferent ducts. These abberant ducts are
vestiges of a long vanished mesopnephros and have no functional
significance. You may or may not see them in your particular
preparation.