Reproduction in Domestic Animals

Dominant Follicle Selection in Cows, Mares and Women 53Table 1. Summary table of granulosa cell genes expressed at highest levels in the largest cohort follicle following emergence, or in the newlyselected dominant follicle compared to the most oestrogenic cohort follicle before selection and(or) the largest subordinate follicle (Evans et al.2004; Forde et al. 2008; Mihm et al. 2008; Zielak et al. 2007). Such identified genes are proposed as gene candidates for the regulation of DFselection in cowsBovine candidate genesfor DF selection Intracellular role Molecular approach ReferenceCell differentiationCYP19A1 a Estradiol synthesis, cell differentiation Custom microarray andqRT-PCR, SAGE andqRT-PCRDQ004742Uncharacterized, splice variant foraromataseGADD45BCell differentiation, response to cellularstress, apoptosisEvans et al. (2004),Mihm et al. (2008)SAGE and qRT-PCR Mihm et al. (2008)SAGE and qRT-PCR Mihm et al. (2008)GSTA2 Steroid synthesis, antioxidant SAGE and qRT-PCR Mihm et al. (2008)INHA Cell differentiation, inhibin synthesis SAGE and qRT-PCR Mihm et al. (2008)LHCGRGonadotrophin receptor, cell differentiationCustom microarray andEvans et al. (2004)qRT-PCRTBC1D1 Cell differentiation, proliferation Custom microarray andZielak et al. (2007)qRT-PCROvary-specific acidic proteinUncharacterized but linked to highSAGE and qRT-PCR Mihm et al. (2008)oestradiol synthesis in pre-ovulatoryfolliclesCell proliferation, apoptosisCCND2 Cell proliferation SAGE and qRT-PCR Mihm et al. (2008)MCL-1 Cell proliferation, antiapoptotic factor Custom microarray andEvans et al. (2004)qRT-PCRMIF Cell proliferation, antiapoptotic factor SAGE and qRT-PCR Mihm et al. (2008)Signal transductionANXA2 Tissue development, signal transduction SAGE and qRT-PCR Mihm et al. (2008)BCAR1 Signal transduction, cell proliferation Custom microarray andForde et al. (2008)qRT-PCRCALM2 Signal transduction SAGE and qRT-PCR Mihm et al. (2008)CLIC1 Signal transduction, chloride transport SAGE and qRT-PCR Mihm et al. (2008)Protein, DNA and RNA synthesisDICE-1Nuclear processes (DNA repair, transcription,Custom microarray andEvans et al. (2004)RNA splicing)qRT-PCRRFC4 Nuclear processes (DNA repair) SAGE and qRT-PCR Mihm et al. (2008)SFRS9 Nuclear processes (RNA splicing) SAGE and qRT-PCR Mihm et al. (2008)SLC22A17 Protein synthesis, ion transport SAGE and qRT-PCR Mihm et al. (2008)a Gene symbols are presented.ConclusionsThe similarities in follicle wave dynamics, the transientFSH rise and its regulation, follicular acquisition ofFSH and LH-responsiveness, and in the differentialpattern of IGF binding protein expression in cohort andDFs are striking between the three monovulatoryspecies. Differences exist mainly between cows andwomen in the follicle wave pattern, between womenand the two animal species in the extent of the FSHdecline, and in the inhibin forms secreted by cohortfollicles, and possibly also in the specific form of IGFbinding protein reduced in DF. Because of the considerableadvantage of large, relatively easily accessiblefollicles, mares present themselves as well-suited forfunctional experiments involving in vivo sampling oradministration of candidate substances. However, thebovine model is most easily monitored, extremely wellcharacterized,and has the advantage that its genomehas been sequenced allowing comparative molecularstudies with human or rodent models of follicle differentiationnot possible so far in other animal species. Inaddition, the bovine model has recently been used todetermine the relationship between low and high cohortfollicle numbers, the primordial follicle pool, andresponse to superovulatory treatment (Ireland et al.2007a,b). Thus, using selected heifers or cows as a modelof low antral follicle numbers may represent an excitingopportunity to study effects of reduced primordial poolsize on future cohort follicle or DF function simulatingevents in pre-menopausal women.ReferencesAcosta TJ, Gastal EL, Gastal MO, Ginther OJ, 2004:Differential blood flow changes between the future dominantand subordinate follicles precede diameter changesduring follicle selection in mares. Biol Reprod 71, 502–507.Acosta TJ, Hayashi K-G, Matsui M, Miyamoto A, 2005:Changes in follicular vascularity during the first follicularwave in lactating cows. J Reprod Dev 51, 273–280.Adams GP, Matteri RL, Kastelic JP, Ko JCH, Ginther OJ,1992: Association between surges of follicle-stimulatinghormone and the emergence of follicular waves in heifers.J Reprod Fertil 94, 177–188.Adams GP, Kot K, Smith CA, Ginther OJ, 1993: Selection ofa dominant follicle and suppression of follicular growth inheifers. Anim Reprod Sci 30, 259–271.Ó 2008 The Authors. Journal compilation Ó 2008 Blackwell Verlag