**2.2 Endocrine Gland derived Vascular Endothelial Growth Factor (EG-VEGF)**

Human endocrine gland derived vascular endothelial growth factor is a secreted angiogenetic mitogen growth factor expressed in the steroidogenic glands, ovary, testis, adrenal and placenta. It induces proliferation, migration and fenestration (formation of membrane discontinue) in capillary endothelial cells derived from endocrine glands. Human EG-VEGF is a 9.6 kDa protein consisting of 86 amino acid residues. Endocrine gland-derived VEGF (EG\_VEGF) belongs to the prokineticin family. It is also known as prokineticn 1 (PK1). Although EG- VEGF is structurally distinct from VEGF, they induce similar angiogenic response in the ovary. The EG- VEGF acts through G-protein couplesd receptors, pkr1.

EG-VEGF was found to be expressed in non-endocrine tissues including endometrium: in human, it is highly expressed during the secretory phase of the menstrual cycle, when angiogenesis occurs. Lee et al evaluated the expression of EG-VEGF and its receptors in eutopic and ectopic endometrial tissues. A significant increase in molecule expression was found in the stromal cells of ectopic endometrium. It is possible that the stromal cells may synthesize EG-VEGF or that it is synthesize in the epithelial cells but is accumulated in the extracellular matrix of stroma. The endocrine gland-vascular endothelial growth factor, through its heparin- binding domain can, as VEGF, accumulated in the extracellular matrix (Lee K et al, 2010).
