. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 134 A. GARM ET Figure 7. Type 3 seta. (A) Scanning electron micrograph of type 3 seta in dorsal row. Planes indicate approximate area of transmission electron micrographs. (B) Close-up of the tip. (C) Semi cross-section ca. 10 ; from tip. The cuticle is divided into six distinct layers (EC, Cu2-Cu5, ML not shown). Cu3 has prominent canals (CuC). Insert = close-up of lumen with ciliary compartment (CC) enclosed by the dendritic sheet (DS), one cell extension (CE). and a sparse extracellular matrix (ECM). (D) Cross-sec
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 134 A. GARM ET Figure 7. Type 3 seta. (A) Scanning electron micrograph of type 3 seta in dorsal row. Planes indicate approximate area of transmission electron micrographs. (B) Close-up of the tip. (C) Semi cross-section ca. 10 ; from tip. The cuticle is divided into six distinct layers (EC, Cu2-Cu5, ML not shown). Cu3 has prominent canals (CuC). Insert = close-up of lumen with ciliary compartment (CC) enclosed by the dendritic sheet (DS), one cell extension (CE). and a sparse extracellular matrix (ECM). (D) Cross-section in nonserrulate part of seta. Cuticle layers 2-5 have fused to form one more or less homogenous layer. Prominent lumen with large amount of extracellular matrix, eight to nine cell extensions, and a ciliary compartment with nine sensory cilia. (E) Cross-section just below the base of the seta. The ciliary compartment is enclosed by a dendritic sheet and 15-20 semicircular sheet cells of two types (SCI, SC2). The sheet cells are surrounded by extracellular matrix. Insert = close-up of ciliary compartment. (F) Cross-section ca. 50 /j,m after E. One cell has a large rootlet (LR); the other cells are sectioned in the region of the basal body (BB) or in the ciliary region (CR) or the paraciliary region (PR). A weak scolopale is seen (Sc). Arrowhead indicates extrusion of sheet cell enclosing sensory cell. (G) Cross section ca. 5 (urn after F. The putative chemosensory cells contain a fragmented rootlet (FR). The mechanosensory cell is in contact with the scolopale via desmosomes (arrowheads). Arrow indicates large ciliary rootlet. sumed from their arrangement and external morphology. The guard setae on P. argus are not serrate but simple (no outgrowths). Most other systems with crustacean mechano- sensitive setae studied so far are sensitive to movements of the surrounding water (Wiese, 1976; Heinisch and Wiese, 1987; Derby, 1989); but this does not seem to be the case with the
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
