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Fig. 1. Blocking vegetal signaling produces permanent blastulae with an expanded
animal plate that differentiates as unpatterned neural tissue. (A-D,F)
Embryos injected with
-cadherin RNA. (A) DIC image of embryo (72
hour) injected with
-cadherin RNA. (B) Anti-serotonin
immunoreactive cells in a
-cadherin-injected embryo. Confocal stack of
the animal pole. (C) Anti-synaptotagmin immunoreactivity (SpSyn B) is
principally in neurites of the serotonergic cells. (D) Merged image of
B,C. (E) Merged image of control embryo (72 hours); serotonin (green)
and synB (magenta) co-localize in apical organ neurons and synB identifies
ciliary band neurons. (F) Detail of serotonergic and non-serotonergic
neurons of the animal plate of a
-cadherin RNA injected embryo (120
hours). (G) Anti-serotonin immunoreactive cells in embryo expressing
Gsk. Inset is DIC image. (H) Permanent blastula from animal cap
blastomeres with abundant unpatterned anti-serotonin immunoreactive cells.
Inset is DIC image. (I) Uninjected embryo (72 hours) expressing SpHnf6
(green) in ciliary band and SpNk2.1 protein (magenta). Only the animal plate
co-expresses these transcription factors. (J) A single confocal,
optical section at the midline showing a lateral view of the region
co-expressing SpHnf6 and SpNk2.1 (bracket). Enlargement of the region shown
with asterisk in inset. o, oral ectoderm; ab, aboral ectoderm. (K-M)
Recombined confocal image of
-cadherin RNA injected embryo from animal
pole. All of the thickened epithelial cells express SpHnf6 (K) and SpNk2.1
(L). (M) Merged image of (K,L). (N) Lateral view of a
-cadherin
RNA-injected embryo labeled with in situ RNA hybridization of SpHnf6 and
immunolocalization of SpNk2.1. Arrowheads indicate the border between thick
and thin epithelium. (O) Single confocal optical section of
-cadherin RNA-injected embryo. Serotonergic cells (green) express
SpNk2.1 (magenta), but SpNk2.1 is cytoplasmic rather than nuclear in these
cells (arrows). Scale bar: 20 µm.