Biovularity and "coalescence of primary follicles" in ovaries with mature teratomas

Several theories have been postulated regarding the origin of ovarian terat omas, including incomplete twinning, neoplastic proliferation of sequestere d totipotent blastomeres or primordial cells, derepression of totipotent ge netic information in the nuclei of somatic cells, and parthenogenetic devel opment of germ cells. At present parthenogenetic development of ova is the most widely accepted theory, primarily because of the presence of a 46 XX k aryotype in almost all mature teratomas. However, some authors have raised the possibility of fusion of ova in the mechanism of formation of ovarian t eratomas. We report the results of a study on ovarian tissue adjacent to 31 teratomas to assess the frequency of biovularity, which could provide evid ence favoring the last theory. On the whole we found biovularity in 26 ovar ies of young patients (mean age, 27 years) with variable numbers of biovula r follicles ranging from 1 in 4 cases to more than 10 in 2 cases; the numbe r of biovular follicles depended on the quantity of ovarian tissue examined as well as on the total number of ova in the tissue. In multiple occasions 2 ova were included within a single follicle; in 24 ovaries the biovularit y was correlated with coalescence of primary follicles characterized morpho logically by all ovoid or hourglass-like shape that resulted from cohesion of 2 follicles. As control cases, 30 ovaries of patients with atl average a ge of 28 years were examined (12 removed for endometriosis, 8 for serous cy stadenoma, 7 for tubal pregnancy and 3 for acute salpingo-oophoritis). Only 1 ovary with endometriosis contained a single biovular follicle. The resul ts suggest that ovarian teratoma development may result from fusion of ova in ovaries containing biovularity and phenomena of coalescence of primary f ollicles.