vas rectum

noun[usually plural]4

1. •
   One of a number of straight vasa (tubes).
2. •
   Any one of many straight capillaries in the kidney that branch off from the arteriolae efferentes (efferent arterioles) of juxtamedullary nephrons, enter the medulla, and surround the loop of Henle, where they function to absorb water and to secrete salt and urea into the renal interstitium, thereby facilitating the production of concentrated urine.

   • Long and almost straight vessels (vasa recta), into which the efferent vessel of those tufts situated at the bases of the pyramids, divides. — 1858
3. •
   Any one of numerous straight arteries that branch off from the arcades of the mesentery of the jejunum and ileum whence they head toward the small intestine.

   • Bleeding from colonic diverticula is caused by rupture of the underlying vas rectum. — 1990
4. •
   (old-fashioned) A straight seminiferous tubule conveying semen from its pertaining tubulus seminiferus contortus (convoluted seminiferous tubule) to the rete testis of the testicle that contains it; now more commonly called the tubulus seminiferus rectus (straight seminiferous tubule).

   • A yellowish semen is generated in the vascula serpentina, is sent down into the vasa recta, and thence deposited in the rete under the albuginea. — 1750