It is estimated that intra-uterine growth restricted piglets represent 25 % of the total number of piglets born. Growth restricted female pigs have impaired reproductive performance postnatally. HHowever, when during gestation this phenotype arises is not known. With this study, the aim was to improve the understanding of foetal ovarian development in normal and small foetuses throughout gestation. Female Large White X Landrace foetuses were obtained at gestational day (GD) 45, 60 and 90 (n = 5–6 litters/GD). Histological analysis of GATA4 stained foetal ovaries at GD60 and 90 indicated there were fewer primary follicles (P ≤ 0.05) in the foetuses weighing the least compared to those with a weight similar to the mean for the litter (CTMLW) at GD90. Plasma oestradiol concentrations were less in the foetuses with lesser weights compared with greater weight foetuses at GD90 (P ≤ 0.05). The RNA was extracted from ovaries of the lesser weight and CTMLW foetuses at GD45, 60 and 90 and qPCR was performed to quantify relative abundance of 12 candidate mRNAs for which encoded proteins that modulate ovarian function and development. Gestational changes in relative abundances of CD31, PTGFR, SPP1 and VEGFA mRNA transcripts were observed. Relative abundance of KI67 (P = 0.066) and P53 (P ≤ 0.05) was less in ovaries of the lesser weight compared to CTMLW foetuses at GD60. There was a lesser relative abundance of PTGFR mRNA transcript in ovaries from the foetuses with lesser weight compared to CTMLW foetuses at GD45 and 60 (P ≤ 0.05). These findings indicate that postnatal differences in the reproductive potential of growth restricted females are programmed early in gestation. It is hoped that further investigation will improve the understanding of the relationship between prenatal reproductive development and postnatal reproductive performance.

据估计，宫内生长受限的仔猪占出生仔猪总数的 25%。生长受限的母猪在出生后会损害繁殖性能。然而，在妊娠期间这种表型何时出现尚不清楚。通过这项研究，目的是提高对整个妊娠期间正常和小胎儿的胎儿卵巢发育的了解。在妊娠日 (GD) 45、60 和 90 ( n = 5–6 窝/GD)获得雌性大白 X 长白胎儿。GD60 和 90 时 GATA4 染色的胎儿卵巢的组织学分析表明初级卵泡较少（P≤ 0.05) 在 GD90 时，与体重与窝平均值 (CTMLW) 相似的胎儿相比，体重最轻的胎儿。在 GD90 时，与体重较大的胎儿相比，体重较轻的胎儿的血浆雌二醇浓度较低 ( P ≤ 0.05)。在 GD45、60 和 90 时从体重较轻的卵巢和 CTMLW 胎儿中提取 RNA，并进行 qPCR 以量化 12 种候选 mRNA 的相对丰度，这些 mRNA 编码了调节卵巢功能和发育的蛋白质。观察到CD31、PTGFR、SPP1和VEGFA mRNA 转录物相对丰度的妊娠变化。KI67 的相对丰度( P = 0.066) 和与 GD60 的 CTMLW 胎儿相比，体重较轻的卵巢中的P53 ( P ≤ 0.05) 较低。与 GD45 和 60 的 CTMLW 胎儿相比，体重较轻胎儿的卵巢中PTGFR mRNA 转录物的相对丰度较低（P ≤ 0.05）。这些发现表明，生长受限雌性的生殖潜力的出生后差异在妊娠早期就已被编程。希望进一步的调查能增进对产前生殖发育与产后生殖性能关系的认识。