. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MOUTH CLOSURE IN BEROE 465. Figure 2. Zone of adhesion between Mg-rela\ed lip segments of Btvwsp. under imposed tension (large arrows). A,B. The paired lip segments (left and right) are joined symmetrically along a zone (arrowheads) of stretched stomodaeal walls (w). The lip edges and furrowed macrociliary fields (M) are at the top; the stomodaeum (s) is down. Note that the attachment zone is located a short distance aboral to the macrociliary fields. B, Continued tension narrows the adhesive contact between the stretched li
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MOUTH CLOSURE IN BEROE 465. Figure 2. Zone of adhesion between Mg-rela\ed lip segments of Btvwsp. under imposed tension (large arrows). A,B. The paired lip segments (left and right) are joined symmetrically along a zone (arrowheads) of stretched stomodaeal walls (w). The lip edges and furrowed macrociliary fields (M) are at the top; the stomodaeum (s) is down. Note that the attachment zone is located a short distance aboral to the macrociliary fields. B, Continued tension narrows the adhesive contact between the stretched lip surfaces (arrowheads). A short time later the lips snapped apart. C, Face view of the adhesion zone between stretched, separating stomodaeal walls (w) by darkfield microscopy. The adhesive contact runs medially (arrowheads) and scatters more light than the stretched surfaces. Scale bar: A,B. 165 j/m; C, 110 nm. First pattern of mouth adhesion: B. sp. Treatment of B. sp. with excess MgCl: abolishes con- traction of the body wall muscles and blocks neurally me- diated ciliary responses ( ciliary inhibition). Mg-relaxed animals swim forward continuously with their mouth closed. The lips resist being pulled apart with forceps, as if they were stuck shut. After being forcibly opened, how- ever, the stomodaeal walls and mouth of MgCl:-anaes- thetized animals gradually close, and the lips re-seal within 10-15 min. Similar observations were made on dissected oral ends. These findings show that mouth closure is functionally reversible and requires neither muscular nor nervous activity to maintain or re-establish Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Fran
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