Venodilation in most of the tissue due to

(Decreases O2 tension): Ref: Mechanisms of clinical signs - Google Books Result books.google.co.in/books?isbn=072958075xMark Dennis, William Talbot Bowen, Lucy Cho - 2012 - MedicalLivedo Reticularis is essentially increased visibility of the venous plexus of the skin. Venodilatation of the vessels and deoxygenation of blood in the plexus are two main factors. In general venodilatation is caued by altered autonomic nervous system function; circulating factors that cause Venodilation; or in response to local hypoxia. Venodilation allows more venous blood to be present in engorged venules, making them larger and easier to see through the skin. Deoxygenation is principally caused by decreased cutaneous perfusion which can be as a result of decreased arteriolar inflow (may be due to vasopasm due to cold, ANS activity, arteriolar thrombosis or increased blood viscosity); or decreased venous outflow (may be due to venous thrombosis, increased blood viscosity)