(Downloading may take up to 30 seconds.
If the slide opens in your browser, select File -> Save As to save it.)
Click on image to view larger version.

Fig. 1. The pharyngeal pouch endoderm supports a two-dimensional web of
supra-cellular actin cables. Side views of embryos (A-F) where Bmp7
expression (A-C) within the pharyngeal pouch endoderm has been used to
highlight the elaboration of pouches along the proximodistal axis and
phalloidin staining (D-F) has been used to visualise f-actin within the pouch
endoderm. (A) At stage 14, two pharyngeal pouches (1pp and 2pp) have formed
and begun to elongate along the proximodistal axis. (B) At stage 15, the third
pharyngeal pouch (3pp) is evident. (C) At stage 18, all three pouches (1pp,
2pp and 3pp) have further elongated and display typical narrow slit-like pouch
morphology. (D-F) Localised accumulation of actin is seen within the endoderm
of each pouch as they undergo proximodistal elongation. (G) High magnification
view of the third pharyngeal pouch (3pp) shows actin organised into a
supracellular actin cable (red arrowhead), assembled along the apical margin
of the endodermal cells (basal margin indicated by an asterisk). (H)
Longitudinal section through the pharyngeal region, (at level indicated in F),
showing pouches as distinct outpocketings of endoderm. The pharyngeal endoderm
is described as pouch endoderm (PE) or interpouch endoderm (IPE). A
two-dimensional web of supracellular cables, which follows the lumenal
contours of the pouch endoderm, appears to be localised to regions where
pouches are forming (red arrowhead) or have just formed, but at lower
abundance in the interpouch endoderm (IPE). OV, otic vesicle; aa, arch artery.
Anterior is towards the left.