Superovulatory Response of One Ovary Is Related to the Micro- and Macroscopic Population of Follicles in the Contralateral Ovary of the Cow

Abstract

We hypothesized that the ovulatory response of one ovary to FSH would be related positively to the size of the primordial and growing pools of follicles in the other ovary. Nonlactating cows (n = 26) were unilaterally ovariectomized and 2 days later were superovulated. The superovulatory response was classified as Low (< 5 corpora lutea [CL]), Medium (5-14 CL), or High (> 14 CL). Surface follicles on the ovary removed before superovulation were classified as small (1-3 mm), medium (3-7 mm), or large ( > 7 mm), and the ovary was then fixed and serially sectioned. Follicles </= 1 mm in diameter in 388 +/- 38 fields (2 x 2 mm) per cow were classified as primordial, primary, secondary, or tertiary. By classification, Suboptimal ovaries contained < 100 follicles </= 1 mm and Optimal ovaries contained > 250 follicles </= 1 mm. Number of CL was correlated positively with total number of primordial, tertiary, and medium surface follicles. Number of Empty fields (2 x 2-mm fields containing no follicles) was correlated negatively with superovulatory response and number of primordial follicles. Number of CL was related to number of tertiary follicles in a positive linear manner and the number of medium follicles in a positive quadratic manner (r 2 = 0.66). Numbers of primordial, tertiary, small surface follicles, medium surface follicles, and total surface follicles were lower (p </= 0.06) in the Low superovulatory response group than in the Medium or High group. Suboptimal ovaries had fewer small surface follicles and fewer CL than Optimal ovaries (p < 0.05). We conclude that superovulatory response in cattle is related positively to the pools of primordial and growing follicles in the bovine ovary.

Anti-Müllerian Hormone (AMH) and fertility management in agricultural species

“…Such responsiveness is negatively associated with aging and is linked to a reduction in number of follicles and oocytes in ovaries in women (Beckers et al 2002, Styer & Toth 2011, Dewailly et al 2014 and in cattle (Kawamata 1994, Cushman et al 1999, Taneja et al 2000, Singh et al 2004. We documented for the first time that young adult cattle with low AFC have a diminished responsiveness to superovulation (lower number of corpora lutea and of recovered embryos/unfertilized oocytes) and produced fewer high-quality embryos compared to age-matched cattle with high AFC (Ireland et al 2007).…”

“…This could explain why granulosa cells in cattle with a low AFC were refractory to FSH action and consequently produced less AMH compared to granulosa cells from cattle with a high AFC. In addition, the refractoriness of granulosa cells to FSH could also at least partially explain why cattle (Kawamata 1994, Cushman et al 1999, Taneja et al 2000, Singh et al 2004, Ireland et al 2007) and women (Beckers et al 2002, Broekmans et al 2006, Styer & Toth 2011, Dewailly et al 2014) with a small ovarian reserve and correspondingly chronically high FSH secretion during reproductive cycles respond poorly to FSH stimulation during assisted reproductive technologies.…”

Changes in granulosa cells' gene expression associated with increased oocyte competence in bovine

“…The application of all time periods to each individual animal was designed to minimize individual variations in the genomic response. This design is even more important in the context of known variability in the response to hormones both across and within individuals (Kawamata 1994, Cushman et al 1999, Rico et al 2009). The physiological observations of oocyte quality as reflected by the blastocyst rates across coasting duration indicates an initial increase (20-68 h) followed The granulosa cell expression during this period of increasing competence is associated with expression of genes leading to apoptosis increases (FOXO3, STAT6, and CASP8) and cellular proliferation decreases (TP53, SMARCB1, STAT4, and CCL2).…”

Superovulation in cattle: practical aspects of gonadotropin treatment and insemination

“…The number of small follicles 3-6 mm in diameter on both ovaries before the superovulatory treatment was found to be significantly correlated with the numbers of corpora lutea after superovulation (r = 0.440, P < 0.001), total recovered ova (r = 0.503, P < 0.001) and transferable recovered embryos (r = 0.482, P < 0.001). More recently, Cushmann et al [12] found that the number of CL is correlated positively with the total number of primordial, tertiary, and medium surface follicles. The number of CL is related to the number of tertiary follicles in a positive linear manner and the number of medium follicles in a positive quadratic manner.…”