PhD thesis
PhD thesis
PhD thesis
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70 Submitted manuscript<br />
Chapter IV<br />
Same stage as in J with animal view onto the future dorso-anterior part of the larva. The two<br />
fields of TtrNot expressing cells which are interconnected by a narrow band of TtrNot expressing<br />
cells (arrowhead) are visible. (L) Elongated gastrula with small blastopore (asterisk). The TtrNot<br />
expressing cells are distributed equally along the posterior part of the future larval apical lobe.<br />
(M) Ventral view of an early three-lobed larva with apical tuft (at), anterior lobe (al), mantle lobe<br />
(ml), and pedicle lobe (pl). The blastopore (asterisk) is closed. The border between ectoderm<br />
(ec) and mesoderm (ms) is visible in the mantle and pedicle lobe. TtrNot expressing cells are<br />
distributed in the posterior part of the apical lobe (indicated by the dashed line). (N) Ventroanterior<br />
view of a larva with all larval lobes fully established: apical lobe (al), mantle lobe (ml),<br />
pedicle lobe (pl). The blastopore (asterisk) is closed and TtrNot expressing cells are distributed<br />
in a ring along the posterior part of the apical lobe. (O) Dorsal view of a fully differentiated<br />
larva with apical lobe (al), mantle lobe (ml), pedicle lobe (pl), and setae (s). TtrNot is no longer<br />
expressed. (P) Posterior view of a juvenile at 360 hours after settlement (hps) with pedicle (p),<br />
anlage of both valves (v) ,and larval setae (s), which extend beyond the valves. TtrNot is not<br />
expressed.<br />
Fig. 4 Cdx expression in<br />
Terebratalia transversa. Scale bars<br />
equal 50 µm, age is given in hours<br />
after fertilization (hpf). (A) Gastrula<br />
stage, TtrCdx (purple) is expressed in<br />
the ectoderm of the posterior pole of<br />
the blastopore (asterisk). (B) Gastrula<br />
stage slightly older than the one in A,<br />
TtrCdx expression on the posterior<br />
side of the blastopore (asterisk) is<br />
more intense than in A. (C) Maximum<br />
projection image of a confocal<br />
reflection scan of a specimen with<br />
similar expression pattern as in B,<br />
showing that TtrCdx is still limited to<br />
the ectoderm. (D) Early larva with<br />
modest expression of TtrCdx (arrow)<br />
in the ventral part of the future mantle<br />
lobe (ml), immediately posterior to<br />
the blastopore (asterisk). The future<br />
apical lobe (al) and posterior lobe (pl)<br />
can already be distinguished. (E) Early<br />
three-lobed larva with apical lobe (al),<br />
mantle lobe (ml), and pedicle lobe<br />
(pl). TtrCdx (arrow) is expressed in<br />
the posterior part of the mantle lobe,<br />
further posterior from the almost closed blastopore (asterisk) than in previous stages. The<br />
larval apical lobe (al), mantle lobe (ml), and pedicle lobe (pl) are further developed. (F) Fully<br />
established larva with expression of TtrCdx (arrow) in the center of the ventral part of the mantle<br />
lobe (ml). Apical lobe (al), mantle lobe, and pedicle lobe (pl) are fully developed and four sets<br />
of larval setae (se) extend from the mantle lobe.