The lymph vessels of the testis (Figure 38) and epididymis run in the spermatic cord into the abdominal cavity, and, from here, drain to the medial iliac and lumbar aortic lymph nodes, and, in rare cases, to the hypogastric lymph nodes as well.
The lymph vessels of the testis (Figure 31: w) form extremely numerous and extremely fine networks in the tunica albuginea (capsule). These lymph vessels fully penetrate the entire tunica albuginea and continue into the tunica albuginea lining the epididymis pouch and into the tunica albuginea of the epididymis (Figure 31: x). Due to this vascular structure, the lymphatic networks in the tunica albuginea of the epididymis pouch and the epididymis receive lymph from the networks in the tunica albuginea of the testis.
Numerous lymph vessels of varying sizes emerge from these lymphatic networks at the epididymis, particularly at its dorsal border and caput epididymis (head), and mostly accompany the blood vessels of the spermatic cord, forming rich, coarse networks, especially in the half of the spermatic cord facing the testis (see Figure 31). A smaller number of lymph vessels of the testis and epididymis either run in the mesorchium or accompany the ductus deferens (Figure 31: y’). All these lymph vessels are in proximity to each other at the inner inguinal ring, and at this location, there are 3 to 4 vessels.
From the inner inguinal ring, some of the lymph vessels run in the plica vasculosa in a craniodorsal direction towards the medial iliac lymph node (Figure 31: 1) and the lumbar aortic lymph nodes (Figure 31: 2, 2’). These lymph vessels usually drain to the caudal lumbar aortic lymph nodes (Figure 31: 2), though sometimes they also drain to the more cranially located lymph nodes (Figure 31: 2’), and, at times, even to those located at the renal artery and vein. Usually, the lymph vessels open into both the medial iliac and lumbar aortic groups of lymph nodes, less often only into the lumbar aortic lymph nodes.
Other lymph vessels (1 to 2 vessels) from this group accompany the ductus deferens (vas deferens) from the inner inguinal ring to the neck of the urinary bladder before turning to drain into the medial iliac lymph node (Figure 31: 1). More frequently, one of these lymph vessels will also drain into the hypogastric lymph nodes (Figure 31: 3), as shown in Figure 31.
Frequently, some of the lymph vessels draining from the testis to the lumbar aortic lymph nodes may fill with dye up to the renal capsule, where they connect with the lymph vessels of the renal capsule (Figure 31: 8). Furthermore, the lymph vessels of the testis were frequently observed (in about two-thirds of all examined dogs) to open directly, i.e. without having passed a lymph node, into the cisterna chyli. Usually, this behaviour was shown by 1 lymph vessel, while the other lymph vessels of the testis drained into the aforementioned lymph nodes. In other cases, the lymph vessels of the testis merged to a single vessel in the abdominal cavity, from which branches drained to the lymph nodes, but the vessel itself could be followed to the cisterna chyli (for details see Baum ).
Additionally, in 1 case, I observed 1 of the lymph vessels of the testis pierce the tunica vaginalis communis and, near the external inguinal ring, run towards the femoral canal to join its lymph vessels.