title: Venous structures associated with thermoregulation of phocid seal reproductive organs.
abstract: BACKGROUND
  Seal reproductive systems are surrounded by thermogenic muscle and insulating blubber, suggesting elevated temperatures at the gonads and uterus. In the limbs of terrestrial mammals, cooled blood returning from superficial veins is mixed proximally with warm blood returning from deep veins. Thus, mixed cool-superficial and warm-deep venous blood from the hind limbs is returned to the central circulation.
  
  
  METHODS
  We describe structures observed in salvaged carcasses of harbor (Phoca vitulina), gray (Haliochoerus gryphus), harp (Phoca groendlandica), hooded (Cystophora cristata), and ringed (Phoca hispida) seals. Vessels were identified by dissection of injected and uninjected material.
  
  
  RESULTS
  In contrast to terrestrial mammals, phocid seals have anastomoses between the veins of the distal hind limb and the pelvis which allow large volumes of cool blood returning from the skin surface of the flipper to enter the gluteal, pelvic, or pudendo-epigastric veins. This provides a cool-superficial venous return that remains separate from the warm-deep venous return of the femoral veins. The cooled venous blood from the hind flippers supplies venous plexuses lining the inguinal region and the abdominal and pelvic cavities.
  
  
  CONCLUSIONS
  Cooled blood may prevent hyperthermic insult to seal reproductive systems.
authors.affiliation: Marine Mammal Program, U. S. National Museum of Natural History, Washington, DC, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Rommel
authors.forename: G A
authors.initials: GA
authors.lastname: Early
authors.forename: K A
authors.initials: KA
authors.lastname: Matassa
authors.forename: D A
authors.initials: DA
authors.lastname: Pabst
authors.forename: W A
authors.initials: WA
authors.lastname: McLellan
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology / Q000098:blood supply; D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D001842:Bone and Bones / Q000033:anatomy & histology; D004285:Dogs; D005260:Female; D008297:Male; D010388:Pelvis / Q000033:anatomy & histology / Q000098:blood supply; D046048:Seals, Earless / Q000033:anatomy & histology*; D013737:Testis / Q000033:anatomy & histology / Q000098:blood supply*; D014599:Uterus / Q000033:anatomy & histology / Q000098:blood supply*; D014680:Veins / Q000033:anatomy & histology