. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 132 A. GARM ET AL. rows terminating 5 /urn from the setal tip, which lacks pores (Fig. 6A, B). The setules are serrate and decrease in size towards the tip of the seta. The socket forms an intracuticu- lar articulation, and the membranous area is prominent, which adds flexibility to the seta. Internal morphology Type 1 setae (Fig. 4) are innervated by five to nine sensory cells (mean = , n = 10), each of which gives rise to one moditied cilium (Fig. 4D). The unbranched cilia continue to the tip of the seta and contain rel
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 132 A. GARM ET AL. rows terminating 5 /urn from the setal tip, which lacks pores (Fig. 6A, B). The setules are serrate and decrease in size towards the tip of the seta. The socket forms an intracuticu- lar articulation, and the membranous area is prominent, which adds flexibility to the seta. Internal morphology Type 1 setae (Fig. 4) are innervated by five to nine sensory cells (mean = , n = 10), each of which gives rise to one moditied cilium (Fig. 4D). The unbranched cilia continue to the tip of the seta and contain relatively few strands of microtubules (Fig. 4C). Two of the sensory cells contain a large rootlet in their distal end of the cell proper (Fig. 4F, LR), while the other cells have small fragmented rootlets. The numerous sheet cells (>20) tend to lie in semicircles around the bundle of modified cilia (Fig. 4E) and fall into two types. The majority are rather electron- lucent, but two to four of them are electron-dense and contain many vacuoles (Fig. 4E, asterisk). The innermost sheet cell contains a scolopale (Fig. 4F) and forms a den- dritic sheet, which encircles the cilia from just below the basal part of the seta to the distalmost 20 /u,m. In the region of the scolopale, the innermost sheet cell makes a projection that suiTounds one of the sensory cells with a large rootlet (Fig. 4F). The extracellular matrix within the lumen of the dendritic sheet is electron-dense. The next five to eight sheet cells send projections into the lumen of the setal shaft (Fig. 4D), and one of these projections continues to within at least 20 ju,m below the tip (Fig. 4C). We could not identify which sheet cell makes this projection. An extracellular matrix encircles both the ciliary compartment and the cell projec- tions in the setal lumen. The extracellular matrix is most prominent at the base and barely detectable near the tip (Fig. 4C). It contains both electron-dense and electron-lucent area
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
