Morphology and functional characteristics of human ovarian microvascular endothelium

Corpus luteum formation is characterized by a period of extensive vasculari zation, as capillaries in the thecal layer of the collapsed follicle follow ing ovulation invade the previously avascular granulosa layer. In order to study these processes in vitro we have developed an endothelial cell prepar ation from the specific microvasculature of the ovarian follicle. Follicula r aspirates, obtained at oocyte collection for in-vitro fertilization (IVF) , were filtered to obtain fragments of follicle wall. These were set in Mat rigel and then cultured allowing the growth of capillary-like structures th rough the matrix, Upon emergence from the Matrigel the growing cells formed monolayers with the characteristic cobble-stone morphology of endothelial cells. Immunocytochemistry demonstrated the presence of a range of endothel ial-specific markers including von Willebrand factor (vWF), Ulex europeus a gglutinin (UEA)-1, CD31 and E-selectin, as well as VCAM-1, which is normall y associated with stimulated endothelial cells. RT-PCR analysis showed the expression of two receptors for vascular endothelial growth factor (flt-1 a nd KDR), and the endothelial nitric oxide synthase, adding further evidence of their identity as human ovarian microvascular endothelial cells (HOMEC) . Thus, the novel preparative procedure described now allows the generation of HOMEC cultures from readily available material resulting from IVF proce dures.