An ultrastructural study of the rabbit intraovarian lymphatic capillaries after ovulatory stimulus

: Fine distribution and ultrastructural changes in intraovarian lymphatics were studied at accurately timed intervals after the injection of human chorionic gonadotropin (hCG). Four and six hours after hCG injection, edema around the lymphatic capillaries in the theca externa followed that around the blood capillaries. The lymphatic capillaries were markedly dilated and displayed wide openings between neighboring endothelial cells in them. At these stages, lysosome disappeared from the lymphatic endothelium, while macrophages with numerous lysosomes appeared around the lymphatic capillaries and some of them entered the lumen. Eight hours after hCG injection, the ultrastructure of the lymphatic capillaries resumed the appearance of their pre-injection stage. Three days after hCG injection, lymphatic capillaries were observed among the theca lutein cells, but not among the granulosa lutein cells. Edema around the lymphatic capillaries and openings between neighboring endothelial cells reappeared as shown 4 and 6 hours after hCG injection. Five and seven days after hCG injection, macrophages and degenerated lutein cells were observed in the lymphatic capillaries. Fourteen days after hCG injection, lymphatic endothelium began to degenerate, but that of the blood capillaries showed no degenerative signs. These results suggest that the functions of the lymphatic capillaries are absorption and transport of excess fluid, waste products and hormones.