ABSTRACT
The exception to the rule that physiological tissue growth and neovascularization are downregulated processes in the healthy adult is found in the female reproductive system (Gordon et al., 1995; Reynolds et al., 1992; Folkman, 1992; Findlay, 1986; Bassett, 1943). In fact, substantial turnover of tissues involving growth, remodeling, and regression is not just associated with pregnancy, but occurs also in the ovary and the uterus as part of the normal reproductive cycle. Tissue growth and formation of new blood vessels is particularly pronounced in the cyclic ovarian corpus luteum (CL). In large monovulatory species, the CL grows from approximately 200 mg ovulatory tissue to 3-5 g (3-4 cm diameter) within a week. Given that any tissue growth beyond approximately 1 mm3 in size requires adequate supply with blood vessels, it is easily conceivable that growth of the CL must involve a
massive burst of angiogenesis. In fact, the intensity of neovascularization and tissue growth in the CL is far greater than in any naturally occurring human tumor (Eberhard and Augustin, unpublished results).
