. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 40 S. P. LEYS AND H. M. REISWIG. Figure 8. Cell movement in tissue strands (video microscopy). A highly retractile cell (arrowheads) was traced as it moved for 3(1 ^m along a tissue strand at /ynvs'1. Time of frames: (A) (I min: (B) 5 min; (C) 15 min. Bar: 100 ^m. chymal cells in turbellarians are thought to act as a sort of stationary intraccllular circulatory system (Pedersen, 1961); and acid phosphatase staining has shown that amehocytes in the hemal lacuna of crinoids (again, a col- lagen-filled pathway) are involv
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 40 S. P. LEYS AND H. M. REISWIG. Figure 8. Cell movement in tissue strands (video microscopy). A highly retractile cell (arrowheads) was traced as it moved for 3(1 ^m along a tissue strand at /ynvs'1. Time of frames: (A) (I min: (B) 5 min; (C) 15 min. Bar: 100 ^m. chymal cells in turbellarians are thought to act as a sort of stationary intraccllular circulatory system (Pedersen, 1961); and acid phosphatase staining has shown that amehocytes in the hemal lacuna of crinoids (again, a col- lagen-filled pathway) are involved in digestion and trans- port of nutrients (Hein/eller and Welsch, 1997). We cannot rule out a role for the tissue strands in contracting the ostia and water canals to control water flow as suggested for the elongate cells in Verongici (Va- celet, 1966): nonetheless, there is little evidence to sup- port this hypothesis. Although some cells in the strands have what appears to be a highly developed actin cy- toskeleton, and the strands recoiled gently after being cut, none of the strands were wrapped around the water canals or ostia sufficiently to be able to reduce water flow if contracted. Furthermore, localized patches of elongate cells were present in valve- or sphincter-like structures around the water canal system, and these quite possibly function in controlling water flow through the sponge as suggested by Vacelet (1966). and by Reiswig (1971) for those sponges in which flow is not controlled by flagellar activity. The facts that video microscopy did not reveal all cells in the strands to be moving, and that not all cells in the strands are elongate, could also be taken as evidence against the transport hypothesis. But the thickness (100 jjm} of the strands allowed only a few cells at the edges of strands to be observed at high magnification by video microscopy. Despite the low magnification and use of epi-illumination. a few of the highly refractile cells could be cle
Size: 1146px × 2179px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
