aplacental


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Related to aplacental: ovoviviparous, viviparous

a·pla·cen·tal

 (ā′plə-sĕn′tl)
adj.
Having no placenta, as marsupials and monotremes.

aplacental

(ˌeɪpləˈsɛntəl; ˌæplə-)
adj
(Zoology) (of monotremes and marsupials) having no placenta
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.aplacental - having no placentaaplacental - having no placenta; "monotremes and marsupials are aplacental mammals"
placental - pertaining to or having or occurring by means of a placenta; "all mammals except monotremes and marsupials are placental mammals"
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References in periodicals archive ?
On the basis of examination of a small number of reproductive tracts, velvet dogfish have been described as aplacental viviparous sharks that fit the type-II yolk-sac reproductive mode (in which several embryos with attached yolk sacs are contained in utero without uterine compartments) (Otake, 1990).
(2014) in embryos of placental and aplacental sharks, and is probably due to a lower content of inorganic than organic Hg, which has a high degree of affinity for the thiol groups of the muscle tissues (Soares et al., 2011).
Short gestation periods are been described for aplacental viviparous batoids of the families Urolophidae and Urotrygonidae (Wourms 1977; Hamlett & Koob, 1999).