The contraction of small arteries in the perimetrium by presurgical medication with the luteinizing hormone-releasing hormone agonist to patients with leiomyomas: an electron and immunoelectron microscopy.

The remarkable contraction of small arteries occurred in the perimetrium of the uteri with leiomyomas by a presurgical medication P6th the luteinizing hormone-releasing hormone (LHRH) agonist (buserelin). The contracted vessels showed a significant increase in number of the Weibel-Palade (WP) bodies which occasionally underwent the degranulation and the discharge in a manner of exocytosis. By immunoelectron microscopy, localizations of endothelin (ET)-1 immunoreactive gold particles on the WP bodies as well as on cisterns of the rough endoplasmic reticulum (rER) and Golgi apparatus were pronounced in the buserelin-medicated group when compared to the non-medicated one. These findings indicate that the increase of the WP bodies storing ET-1, of which synthesis in the rER-Golgi system enhances, predominantly occurred in the small arteries in the perimetrium by the buserelin-medication prior to the hysterectomy. ET-1, released into the subendothelial layer, seems to play an important role in the contraction of the vascular media in a manner of paracrine.