A number of in vivo assays have bee

A number of in vivo assays have been proposed to studyangiogenesis. These assays utilized various animal species includingmammals (e.g. rats, mice), birds (e.g. chicken, quail), and fish (namelyzebra fish). Chorioallantoic membrane (CAM) is a highly vascularizedtissue of the avian embryo, specialized in respiration [6]. It is formedby the fusion of the (splanchnic) mesodermal layer of the allantoisand the adjacent (somatic) mesodermal layer of the chorion. Thisdouble layered mesoderm has a very rich vascular network. Theextracellular matrix of the CAM promotes angiogenesis through itscontent of fibronectin, laminin and collagen type IV, and thedistribution of specific glycosaminoglycans. The CAM model haslong been preferred for the studies on tumor angiogenesis andmetastasis, as well as the studies of the macromolecules withangiogenic or antiangiogenic activity. After stimulation with anangiogenic compound, the vessel density increases whereas thevessels become less dense and eventually disappear with anantiangiogenic compound [7]. Because of its simplicity and low cost,CAM is the most commonly utilized in vivo angiogenesis model [2].There are several forms of LMWH available for clinical practice.Nadroparin, enoxaparin, tinzaparin, and bemiparin are some of theseforms. In the present study, we aimed to demonstrate and comparethe antiangiogenic potency of these four types of LMWH in the chickembryo chorioallantoic membrane (CAM) model.