文章基本信息

标题：Viviparous stingrays avoid contamination of the embryonic environment through faecal accumulation mechanisms
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作者：Taketeru Tomita ; Masaru Nakamura ; Yasuhisa Kobayashi 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2020
卷号：10
期号：1
页码：1-7
DOI：10.1038/s41598-020-64271-2
出版社：Springer Nature
摘要：In viviparous (live-bearing) animals, embryos face an embryo-specific defecation issue: faecal elimination in utero can cause fatal contamination of the embryonic environment. Our data from the viviparous red stingray (Hemitrygon akajei) reveals how viviparous elasmobranchs circumvent this issue. The exit of the embryonic intestine is maintained closed until close to birth, which allows the accumulation of faeces in the embryonic body. Faecal accumulation abilities are increased by (1) the large intestine size (represents about 400–600% of an adult intestine, proportionally), and (2) the modification in the intestinal inner wall structure, specialized to increase water uptake from the faecal matter. According to the literature, faecal accumulation may occur in embryos of the lamniform white shark as well. The reproductive biology of myliobatiform stingrays and lamniform sharks is characterized by the onset of oral feeding before birth (i.e. drinking of uterine milk and eating of sibling eggs, respectively), which is expected to result in the production of large amounts of faeces during gestation. The strong ability of faecal accumulation in these lineages is therefore likely an adaptation to their unique embryonic nutrition mechanism.