Intraovarianism. Local mechanisms that affect follicle and luteal dynamics in heifers and women†

Intraovarianism is represented by greater follicle activity in right ovary (RO) than left ovary (LO) during the two or three follicular waves per interovulatory interval in heifers and the ovulatory wave in women. In each species, selection between the dominant follicle (DF or F1) and future largest subordinate follicle (F2) is manifested by diameter deviation. The RO has more ≥6 mm predeviation follicles in heifers, more 2-10 mm predeviation follicles in women, and greater frequency of ovulation in each species. The RO propensity for ovulation likely develops before birth or at least before sexual maturity as indicated by (1) heavier RO with more follicles in recently born calves and heavier right fetal gonad with more DNA content in humans and (2) greater RO frequency for largest follicle of a wave in sexually immature heifers and for first ovulation of puberty. In heifers, intraovarianism is also expressed by (1) two-way enhancement effect between DF and corpus luteum (CL) when in same ovary, (2) regression of predeviation follicles when adjacent to the regressing CL, (3) more frequent location of F2 during predeviation in ovary that contains F1, (4) greater diameter increase during recovery of subordinate follicles when in RO with the future DF, and (5) effect of an intraovarian pattern on the pattern in the next wave. The nature of these forms of intraovarianism is not known but may be physical rather than from local passage of factors between structures. Intraovarianism should be considered when studying systemic hormonal effects on ovarian dynamics.