Read More
Date: 27-7-2016
1254
Date: 14-8-2016
1541
Date: 17-1-2017
1204
|
Venous Valves
One-way valves are present in most veins. They are folds of the tunica intima, which protrude into the venous lumen like sails (leaflet valve, velum ) . The leaflet valves can be in the shape of a half-moon or a sickle. Their shapes of ten remind of a martin’s nest 1 . Most valves have two flexible leaflets, which freely move with the bloodstream. Valve leaflets are covered on both faces by a layer of endothelium with an underlying network of intersecting collagen fibers. This fiber network is anchored in the venous wall. The space between the venous wall and the outer edge of the velum (leaflet) is called valve sinus 2 . During normal blood flow through the vein, the leaflets lay against the venous wall, and the valve is open. The leaflet valve prevents the back flow of blood. Valve of a vein from the orbital sinus (pig).
1 Leaflet valve
2 Valve sinus
3 Endothelium of the orbit al sinus
Scanning electron microscopy; magnification: × 180
References
Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgart · New York .
|
|
"عادة ليلية" قد تكون المفتاح للوقاية من الخرف
|
|
|
|
|
ممتص الصدمات: طريقة عمله وأهميته وأبرز علامات تلفه
|
|
|
|
|
الأمين العام للعتبة العسكرية المقدسة يستقبل شيوخ ووجهاء عشيرة البو بدري في مدينة سامراء
|
|
|