Rae M T, Palassio S, Kyle C E, Brooks A N, Lea R G, Miller D W, Rhind S M
Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
Reproduction. 2001 Dec;122(6):915-22.
Gonad development in female sheep fetuses is thought to occur in a number of key stages. The aim of this study was to determine the effects of maternal undernutrition, applied at one or more of these critical stages, on fetal ovarian development. Groups of ewes (n = 11-19) were fed rations providing either 100% (high; H) or 50% (low; L) of energy requirements for live weight maintenance during selected 'windows' during gestation. Control ewes (HH and HHH) were fed the H ration from mating until they were killed at days 50, 65 (HH) or 110 (HHH) of gestation, whereas ewes of other groups were fed the L ration for the periods between day 0 and day 30 of gestation (LH and LHH), day 31 and day 50 or 65 of gestation (HL and HLH), day 65 and day 110 of gestation (HHL) or day 0 of gestation until the animals were killed (LL and LLL). At day 50 of gestation, there was no effect of nutritional treatment on mean fetal mass but compared with HH animals, mean fetal ovarian mass was significantly lower in HL (P < 0.05) and LL (P < 0.001) animals. At day 65 of gestation, there were significantly fewer germ cells (P < 0.05) at the resting, diplotene stage of initial meiosis in LL animals than there were in HH animals, indicating delayed germ cell maturation and onset of meiosis. Qualitative assessment of proliferative cell nuclear antigen immunostaining indicated that, at day 50 of gestation, staining was located predominantly in the germ cells, whereas by day 65 of gestation, staining was confined predominantly to somatic cells. Undernutrition in each one of these windows was associated with delayed ovarian follicular development (P < 0.05-0.001) as measured by development of the granulosa cell layer at day 110 of gestation. This study demonstrates that undernutrition before and during folliculogenesis can delay fetal follicular development.
雌性绵羊胎儿的性腺发育被认为发生在多个关键阶段。本研究的目的是确定在这些关键阶段中的一个或多个阶段施加母体营养不足对胎儿卵巢发育的影响。在妊娠期间的选定“窗口期”，将母羊分组（n = 11 - 19），分别给予维持体重所需能量的100%（高；H）或50%（低；L）的日粮。对照母羊（HH和HHH）从交配开始就饲喂H日粮，直到在妊娠第50、65天（HH）或110天（HHH）处死，而其他组的母羊在妊娠第0天至第30天期间（LH和LHH）、妊娠第31天至第50或65天期间（HL和HLH）、妊娠第65天至第110天期间（HHL）或妊娠第0天直至动物被处死（LL和LLL）饲喂L日粮。在妊娠第50天，营养处理对平均胎儿体重没有影响，但与HH组动物相比，HL组（P < 0.05）和LL组（P < 0.001）动物的平均胎儿卵巢重量显著降低。在妊娠第65天，LL组动物处于减数分裂初始静止双线期的生殖细胞数量明显少于HH组动物（P < 0.05），表明生殖细胞成熟延迟和减数分裂开始延迟。增殖细胞核抗原免疫染色的定性评估表明，在妊娠第50天，染色主要位于生殖细胞中，而到妊娠第65天，染色主要局限于体细胞。通过妊娠第110天颗粒细胞层的发育来衡量，这些窗口期内的每一次营养不足都与卵巢卵泡发育延迟有关（P < 0.05 - 0.001）。本研究表明，卵泡发生之前和期间的营养不足会延迟胎儿卵泡发育。
