placulan.
/ˈplakjᵿlə/, U.S. /ˈplækjələ/ Zoology.
A disc-shaped embryo, occurring as a developmental stage in urochordates and some sponges; a hypothetical primitive metazoan resembling this.
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the world > life > biology > biological processes > procreation or reproduction > embryo or fetus > [noun] > types of at specific stage
colliquament1712
cleavage-cavity1879
placula1884
neoembryo1887
1884 A. Hyatt in Proc. Boston Soc. Nat. Hist. 23 89 The primitive differentiation of the placula into two layers is established in what we have designated the diploplacula.
1884 A. Hyatt in Proc. Boston Soc. Nat. Hist. 23 97 The embryo of Calcispongiæ is also a placula until the same stage.
1886 Encycl. Brit. XX. 420/2 The passage from Protozoa to Metazoa was, according to Bütschli, effected neither by planulan nor gastrula but by a disk-like ‘placula’.
1887 Amer. Naturalist 21 350 Blastospheres..in some cases would represent swollen-up placulæ.
1958 Chambers's Techn. Dict. (ed. 3) 648 Placula, a flattened blastula with reduced segmentation cavity occurring in the development of some Urochorda.
1992 Jrnl. Marine Biol. Assoc. 72 783 The blastula developed into a dorso-ventrally flattened placula at the 70-cell stage.
Derivatives
ˈplacular adj. rare = placulate adj.Apparently only attested in dictionaries or glossaries.
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the world > life > biology > biological processes > procreation or reproduction > embryo or fetus > [adjective] > types of at specific stage
placulate1884
placular1890
1890 Cent. Dict. Placular.
ˈplaculate adj. rare having the form of a placula; disc-shaped.
ΘΚΠ
the world > life > biology > biological processes > procreation or reproduction > embryo or fetus > [adjective] > types of at specific stage
placulate1884
placular1890
1884 A. Hyatt in Proc. Boston Soc. Nat. Hist. 23 150 A full-grown, primitive, placulate form.
This entry has been updated (OED Third Edition, June 2006; most recently modified version published online March 2022).
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n.1884