Document Detail

Histological assessment of selected blood vessels of the phocid seals (northern elephant and harbour seals).
MedLine Citation:
PMID:  20331589     Owner:  NLM     Status:  MEDLINE    
Phocid seals exhibit vascular adaptations that allow them to undertake prolonged deep dives. These vascular adaptations are either unique to phocids, or are modified vascular equivalents to those present in terrestrial mammals. One such adaptation, the aortic bulb, is a spherical enlargement of the ascending aorta specific to phocid seals. Its histological make-up consists of a reinforced tunica media with circular and longitudinal layers of elastic fibres. This reinforcement enables multi-axial deformation of the aortic bulb, thus complementing its function as a prominent elastic reservoir or 'windkessel'. A second adaptation, the hepatic sinus, is an asymmetrical dilation of the abdominal portion of the caudal vena cava and accompanying hepatic veins. The hepatic sinus is comprised of a relatively thin tunica media, with a scant smooth muscle component. The bulk of the sinus wall is comprised of tunica adventitia. A third vascular adaptation distinctive to the phocids is the pericardial venous plexus, composed of convoluted veins circumnavigating the perimeter of the heart. Microscopically, these veins have a thick tunica media and also contain valves. Smaller arteries, venules and distinct capillary beds are observed interspersed in-between these veins. It can be hypothesized, that in seals, certain vascular embryonic development may be arrested at an earlier embryonic stage, resulting in these unusual vascular formations. These modifications play a vital role in blood pressure regulation and distribution of oxygenated blood during prolonged deep diving. The purpose of this work was to elucidate the histological aspects of these unique vascular modifications and relate them to specific function.
H Smodlaka; W Khamas; S Tkalcic; T Golub; L Palmer
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Publication Detail:
Type:  Journal Article     Date:  2010-03-11
Journal Detail:
Title:  Anatomia, histologia, embryologia     Volume:  39     ISSN:  1439-0264     ISO Abbreviation:  Anat Histol Embryol     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-26     Completed Date:  2010-11-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7704218     Medline TA:  Anat Histol Embryol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  178-85     Citation Subset:  IM    
College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA 91766-1854, USA.
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MeSH Terms
Adaptation, Physiological*
Aorta / anatomy & histology
Arteries / anatomy & histology
Blood Pressure
Blood Vessels / anatomy & histology*
Diving / physiology*
Heart / anatomy & histology
Pericardium / anatomy & histology
Phoca / anatomy & histology*,  physiology
Seals, Earless / anatomy & histology*,  physiology
Tunica Media / anatomy & histology
Veins / anatomy & histology
Venae Cavae / anatomy & histology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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