File:EB1911 Lamellibranchia - development of Ostrea edulis.jpg

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Summary

Description
English: Development of the oyster Ostrea edulis. See legend below.
Date published 1911
Source “Lamellibranchia,” Encyclopædia Britannica (11th ed.), v. 16, 1911, p. 120, fig. 23.
Author Modified from Horst.
Permission
(Reusing this file)
Public domain This image comes from the 13th edition of the Encyclopædia Britannica or earlier. The copyrights for that book have expired in the United States because the book was first published in the US with the publication occurring before January 1, 1929. As such, this image is in the public domain in the United States.
English: Legend:
A, Blastula stage (one-cell-layered sac), with commencing invagination of the wall of the sac at bl, the blastopore.
B, Optical section of a somewhat later stage, in which a second invagination has begun—namely, that of the shell-gland sk.
bl, Blastopore.
en, Invaginated endoderm (wall of the future arch-enteron).
ec, Ectoderm.
C, Similar optical section at a little later stage. The invagination connected with the blastopore is now more contracted, d; and cells, me, forming the mesoblast from which the cœlom and muscular and skeleto-trophic tissues develop, are separated.
D, Similar section of a later stage. The blastopore, bl, has closed; the anus will subsequently perforate the corresponding area. A new aperture, m, the mouth, has eaten its way into the invaginated endodermal sac, and the cells pushed in with it constitute the stomodaeum. The shell-gland, sk, is flattened out, and a delicate shell, s, appears on its surface. The ciliated velar ring is cut in the section, as shown by the two projecting cilia on the upper part of the figure. The embryo is now a Trochosphere.
E, Surface view of an embryo at a period almost identical with that of D.
F, Later embryo seen as a transparent object.
m, Mouth.
ft, Foot.
a, Anus.
e, Intestine.
st, Stomach.
tp, Velar area of the prostomium. The extent of the shell and commencing upgrowth of the mantle-skirt is indicated by a line forming a curve from a to F.

N.B.—In this development, no part of the blastopore persists either as mouth or as anus, but the aperture closes—the pedicle of invagination, or narrow neck of the invaginated arch-enteron, becoming the intestine. The mouth and the anus are formed as independent in-pushings, the mouth with stomodaeum first, and the short anal proctodaeum much later. This interpretation of the appearances is contrary to that of Horst, from whom our drawings of the oyster’s development are taken. The account given by the American William K. Brooks differs greatly as to matter of fact from that of Horst, and appears to be erroneous in some respects.

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current17:56, 17 April 2019Thumbnail for version as of 17:56, 17 April 2019775 × 985 (261 KB)Bob Burkhardt{{Information |description ={{en|1=Development of the oyster ''Ostrea edulis''.}} |date =published 1911 |source =“Lamellibranchia,” ''Encyclopædia Britannica'' (11th ed.), v. 16, 1911, p. 120, fig. 23. |author =Modified from Horst. |permission ={{PD-Britannica}} }} Category:Ostrea edulis Category:Animal embryos
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