Uterine epithelial changes during placentation in the viviparous skink Eulamprus tympanum
Uterine epithelial changes during placentation in the viviparous skink Eulamprus tympanum
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DOI：
10.1002/jmor.10520
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发表时间：
2007-05
影响因子：
1.5
通讯作者：
S. M. Adams;S. Lui;S. M. Jones;M. Thompson;C. Murphy
中科院分区：
文献类型：
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作者：
S. M. Adams;S. Lui;S. M. Jones;M. Thompson;C. Murphy
我们用扫描电子显微镜（SEM）和透射电子显微镜（TEM）来描述完整的个体发育的简单胎盘和发展的卵黄囊胎盘和绒毛尿囊胎盘从非生殖通过产后阶段在母体子宫上皮的澳大利亚石龙子，Eulamprus鼓室。我们选择了E。鼓膜是一个简单的，非侵入性胎盘的物种，我们知道，在妊娠期间几乎没有净营养吸收，以发展关于胎盘功能的假设，并确定卵生和胎生条件之间的任何差异。胎盘从胚胎29期开始分化为绒毛膜尿囊胎盘和卵黄囊胎盘;这两种胎盘都是简单的结构，没有专门的母胎连接特征。子宫上皮细胞不是Claire Weekes先前描述的鳞状细胞，而是柱状细胞，随着妊娠的进展，由于下方毛细血管的压力而变得越来越细。当雌性无生殖能力时，子宫腔表面是平坦的，含有电子致密囊泡的微绒毛细胞部分掩盖了纤毛细胞。随着卵黄发生的进展，微绒毛细胞的肥大程度比非生殖雌性的要轻。排卵和受精后，围绕卵子周围的子宫上皮没有区域分化。第一次分化，与绒毛尿囊胎盘和卵黄囊胎盘有关，发生在胚胎阶段29，并持续到阶段39。随着妊娠的进行，子宫绒毛尿囊胎盘形成脊状突起，微绒毛细胞肥大程度减轻，纤毛细胞减少，下方血管增大，子宫表面的腺体开口更加明显。相反，卵黄囊胎盘没有特殊的折叠，细胞具有随机的方向，微绒毛细胞在整个妊娠期间保持肥大。然而，随着妊娠的进行，纤毛细胞变得不那么丰富，在绒毛尿囊胎盘中也可以看到。子宫腔内可见分泌囊泡。所有胎盘分化和细胞细节在第40期丢失，子宫结构在2周内恢复到非生殖状态。循环孕酮浓度开始在卵黄发生后期上升，在胚胎期28-30达到峰值，并在妊娠后期35期后下降。产卵和胎盘分化的时间之间的一致性表明，卵生和简单的胎盘胎生有鳞动物在子宫妊娠期间的相似性。J. Morphol.，2007.© 2007 Wiley利斯公司
We used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to describe the complete ontogeny of simple placentation and the development of both the yolk sac placentae and chorioallantoic placentae from nonreproductive through postparturition phases in the maternal uterine epithelium of the Australian skink, Eulamprus tympanum. We chose E. tympanum, a species with a simple, noninvasive placenta, and which we know, has little net nutrient uptake during gestation to develop hypotheses about placental function and to identify any difference between the oviparous and viviparous conditions. Placental differentiation into the chorioallantoic placenta and yolk sac placenta occurs from embryonic Stage 29; both placentae are simple structures without specialized features for materno/fetal connection. The uterine epithelial cells are not squamous as previously described by Claire Weekes, but are columnar, becoming increasingly attenuated because of the pressure of the impinging underlying capillaries as gestation progresses. When the females are nonreproductive, the luminal uterine surface is flat and the microvillous cells that contain electron‐dense vesicles partly obscure the ciliated cells. As vitellogenesis progresses, the microvillous cells are less hypertrophied than in nonreproductive females. After ovulation and fertilization, there is no regional differentiation of the uterine epithelium around the circumference of the egg. The first differentiation, associated with the chorioallantoic placentae and yolk sac placentae, occurs at embryonic Stage 29 and continues through to Stage 39. As gestation proceeds, the uterine chorioallantoic placenta forms ridges, the microvillous cells become less hypertrophied, ciliated cells are less abundant, the underlying blood vessels increase in size, and the gland openings at the uterine surface are more apparent. In contrast, the yolk sac placenta has no particular folding with cells having a random orientation and where the microvillous cells remain hypertrophied throughout gestation. However, the ciliated cells become less abundant as gestation proceeds, as also seen in the chorioallantoic placenta. Secretory vesicles are visible in the uterine lumen. All placental differentiation and cell detail is lost at Stage 40, and the uterine structure has returned to the nonreproductive condition within 2 weeks. Circulating progesterone concentrations begin to rise during late vitellogenesis, peak at embryonic Stages 28–30, and decline after Stage 35 in the later stages of gestation. The coincidence between the time of oviposition and placental differentiation demonstrates a similarity during gestation in the uterus between oviparous and simple placental viviparous squamates. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.