The ovarian and uterine ligaments: a light- and electron-microscopic study in the rat and guinea pig.

Abstract

Histological and histochemical light-microscopy techniques, supplemented by electron microscopy have been used to study the structure and autonomic innervation of the uterine and ovarian ligaments in the adult rat and guinea pig. In both species, the smooth muscle of the uterine ligament was continuous with that of the myometrium at the tubouterine junction and with the smooth muscle of the ovarian ligament. The musculature of the latter also extended into the mesosalpinx and the ovarian bursa, capsule and hilus. Using electron microscopy, smooth muscle cells of both ligaments were usually separated from their neighbours by small amounts of connective tissue, although regions of close approach between adjacent cells were frequently observed. In these areas, the plasma membranes of apposing smooth muscle cells were separated by 10–15 nm and were devoid of an intervening basal lamina. Concerning the arrangement of autonomic nerves, the smooth muscle of the uterine and ovarian ligaments in both species was not supplied by acetylcholinesterase-containing nerves. In the guinea pig, however, numerous noradrenergic nerves were observed amongst the smooth muscle cells of the uterine and ovarian ligaments, the mesosalpinx and the ovarian capsule and bursa. These findings were confirmed using the electron microscope, in which nerve terminal regions*containing characteristic small, dense-cord vesicles were encountered lying 50–100 nm from adjacent muscle cells. In contrast, the smooth muscle cells of the rat uterine and ovarian ligaments were devoid of a noradrenergic nerve supply. These results have been correlated with the observations of previous workers, and the significance of the present findings, particularly in relation to the functional activity of the adult uterine and ovarian ligaments, has been discussed.