. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AURICULARIAN NERVOUS SYSTEM 457 %--. CSZte? '- »«• FIGURE 24. Transverse section through the epidermis at the apical end of an auricularia larva showing nerve cells (n) and axons (a) that are not within the circumoral ciliary band. TEM. Bar = 2 /urn. FIGURE 25. Detail of nerve cell from the epidermis at the apical end of a larva. TEM. Bar = 1 nm. FIGURE 26. Detail of axons underlying the epidermis at the apical end of a larva. TEM. Bar = ^m. FIGURE 27. Section through a blastocoelar mesenchyme cell associated with the ci
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AURICULARIAN NERVOUS SYSTEM 457 %--. CSZte? '- »«• FIGURE 24. Transverse section through the epidermis at the apical end of an auricularia larva showing nerve cells (n) and axons (a) that are not within the circumoral ciliary band. TEM. Bar = 2 /urn. FIGURE 25. Detail of nerve cell from the epidermis at the apical end of a larva. TEM. Bar = 1 nm. FIGURE 26. Detail of axons underlying the epidermis at the apical end of a larva. TEM. Bar = ^m. FIGURE 27. Section through a blastocoelar mesenchyme cell associated with the circumoral ciliary band. TEM. Bar = 1 /urn. system (Mortensen, 1920; Garstang, 1939; Strathmann, 1971, 1975). Strathmann (1971) observed that in the presence of excess MgCl2, an inhibitor of synaptic trans- mission in some animals, overall reversals of the ciliary band, rejection of particles from the esophagus, and localized reversal associated with feeding were blocked. The principal effector organs of the larva are the ciliated cells of the ciliary bands and the musculature of the esophagus. The neural components observed in this study are associated with larval effectors and probably function primarily in coordinating swimming and feeding behaviors of the larva. Conceivably the nervous system mediates overall ciliary reversals and coordinates reverse peristalsis of the esophageal musculature with reversals. It is also possible that the nervous system mediates the localized ciliary reversals involved with particle capture. The sparse distribution of nerve cells within the ciliary band would argue against such a hypothesis as it would be expected that the spacing of the cells would approximate the length of band involved in a localized reversal. Although this distance is not known for sure (Strathmann, 1971), it would appear to be much shorter than the 50 to 150 pm observed between nerve cells of glyoxylic acid treated specimens. The nervous system of the echinopluteus has
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
