EUTHERIAN-LIKE REPRODUCTIVE SPECIALIZATIONS IN A VIVIPAROUS REPTILE
EUTHERIAN-LIKE REPRODUCTIVE SPECIALIZATIONS IN A VIVIPAROUS REPTILE
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DOI：
10.1073/pnas.81.15.4860
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发表时间：
1984-01-01
期刊：
影响因子：
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通讯作者：
BEUCHAT, CA
中科院分区：
文献类型：
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作者：
BLACKBURN, DG;VITT, LJ;BEUCHAT, CA
巴西胎生短尾蜥蜴Mabuya Heathi展示了一套被广泛认为仅限于真兽类哺乳动物的生殖专门化。这种石龙蛋排卵是已知的最小的爬行动物卵(.simeq.直径1.0毫米)。胎盘运输占围产期胎儿干质量的99%，这意味着胎盘营养程度比任何其他非哺乳动物脊椎动物的报告都要大。胎盘的形态和胎儿生长的时间与母婴营养转移中的绒毛尿囊胎盘有关。在胚胎干重显著增加之前，卵黄囊胎盘开始退化。性腺早熟和将生殖投资推迟到排卵后才能使雌性在3-4个月内怀孕。年龄，早在达到完全的成人身体大小之前。
The viviparous Brazilian scincid lizard Mabuya heathi exhibits a suite of reproductive specializations widely believed to be confined to the eutherian mammals. This skink ovulates the smallest known reptilian egg (.simeq. 1.0 mm in diameter). Placental transport accounts for > 99% of the dry mass of the periparturient fetus, representing a degree of placentotrophy proportionately greater than that reported in any other non-mammalian vertebrate. Placental morphology and the timing of fetal growth implicate the chorioallantoic placenta in maternal-fetal nutrient transfer. The yolk sac placenta regresses prior to any major increase in embryonic dry mass. Precocial gonadal maturation and postponement of reproductive investment until well after ovulation enables females to become pregnant at 3-4 mo. of age, long before attainment of full adult body size.