摘要:

The organization of the roots, ganglia and peripheral distribution of the rami of the cranial nerves of larval and juvenile Senegal bichirs was examined with a wide range of techniques, including gross dissection and histological preparations. The profundal nerve of bichirs is completely separate from the trigeminal nerve and innervates the skin overlying the orbit and snout, and there is no evidence that a superficial ophthalmic ramus of the trigeminal nerve exists. Bichirs appear to retain all six pairs of lateral line nerves that characterized the earliest gnathostomes, but the sensory ganglia of the anterodorsal and otic lateral line nerves have fused, and the sensory ganglia of the anterodorsal and anteroventral lateral line nerves are partially fused, which appears to be a shared derived character of ray-finned fishes. The anteroventral lateral line nerve of bichirs retains mandibular and opercular rami, a primitive feature shared with other bony fishes, and the fibers of the opercular ramus innervate all postotic ampullary organs. Surprizingly, bichirs, unlike most nonteleost bony fishes, have lost the spiracular organ. The lateral ramus of the posterior lateral line nerve of bichirs is divided into a pars dorsalis and a pars ventralis, which appears to be a shared derived character of bony fishes. The glossopharyngeal and vagal nerves of bichirs exhibit lateral and medial sensory ganglia, and this appears to be a shared derived character of bony fishes. The posttrematic rami of the glossopharyngeal nerve and both the pre- and posttrematic rami of the vagal nerve of bichirs are divided, which appears to be a shared derived feature of bony fishes. The hypobranchial nerve of bichirs is unusual in that it is formed by only two spinal nerves, a pattern also seen in gars, but not other bony fishes, and apparently a uniquely derived character.

ISSN:0006-8977    

DOI:10.1159/000113229

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The organization of the roots, ganglia and peripheral distribution of the rami of the cranial nerves of larval and juvenile Senegal bichirs was examined with a wide range of techniques, including gross dissection and histological preparations. The profundal nerve of bichirs is completely separate from the trigeminal nerve and innervates the skin overlying the orbit and snout, and there is no evidence that a superficial ophthalmic ramus of the trigeminal nerve exists. Bichirs appear to retain all six pairs of lateral line nerves that characterized the earliest gnathostomes, but the sensory ganglia of the anterodorsal and otic lateral line nerves have fused, and the sensory ganglia of the anterodorsal and anteroventral lateral line nerves are partially fused, which appears to be a shared derived character of ray-finned fishes. The anteroventral lateral line nerve of bichirs retains mandibular and opercular rami, a primitive feature shared with other bony fishes, and the fibers of the opercular ramus innervate all postotic ampullary organs. Surprizingly, bichirs, unlike most nonteleost bony fishes, have lost the spiracular organ. The lateral ramus of the posterior lateral line nerve of bichirs is divided into a pars dorsalis and a pars ventralis, which appears to be a shared derived character of bony fishes. The glossopharyngeal and vagal nerves of bichirs exhibit lateral and medial sensory ganglia, and this appears to be a shared derived character of bony fishes. The posttrematic rami of the glossopharyngeal nerve and both the pre- and posttrematic rami of the vagal nerve of bichirs are divided, which appears to be a shared derived feature of bony fishes. The hypobranchial nerve of bichirs is unusual in that it is formed by only two spinal nerves, a pattern also seen in gars, but not other bony fishes, and apparently a uniquely derived character.

ISSN:0006-8977    

DOI:10.1159/000316272

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The organization of the roots, ganglia and peripheral distribution of the rami of the cranial nerves of larval and juvenile Senegal bichirs was examined with a wide range of techniques, including gross dissection and histological preparations. The profundal nerve of bichirs is completely separate from the trigeminal nerve and innervates the skin overlying the orbit and snout, and there is no evidence that a superficial ophthalmic ramus of the trigeminal nerve exists. Bichirs appear to retain all six pairs of lateral line nerves that characterized the earliest gnathostomes, but the sensory ganglia of the anterodorsal and otic lateral line nerves have fused, and the sensory ganglia of the anterodorsal and anteroventral lateral line nerves are partially fused, which appears to be a shared derived character of ray-finned fishes. The anteroventral lateral line nerve of bichirs retains mandibular and opercular rami, a primitive feature shared with other bony fishes, and the fibers of the opercular ramus innervate all postotic ampullary organs. Surprizingly, bichirs, unlike most nonteleost bony fishes, have lost the spiracular organ. The lateral ramus of the posterior lateral line nerve of bichirs is divided into a pars dorsalis and a pars ventralis, which appears to be a shared derived character of bony fishes. The glossopharyngeal and vagal nerves of bichirs exhibit lateral and medial sensory ganglia, and this appears to be a shared derived character of bony fishes. The posttrematic rami of the glossopharyngeal nerve and both the pre- and posttrematic rami of the vagal nerve of bichirs are divided, which appears to be a shared derived feature of bony fishes. The hypobranchial nerve of bichirs is unusual in that it is formed by only two spinal nerves, a pattern also seen in gars, but not other bony fishes, and apparently a uniquely derived character.

ISSN:0006-8977    

DOI:10.1159/000113230

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

We recently obtained the brain of a rare lemuroid primate, Cheirogaleus medius. The brain was not perfused before death, but rather fixed by immersion shortly thereafter. In both flat-mounted and transversely sectioned tissue, we were able to clearly demonstrate periodic zones of high cytochrome oxidase (CO) activity in the primary visual cortex, resembling the so-called 'blobs' described in many other primate species. Our results contrast with a previous report indicating that blobs are absent in Cheirogaleus medius and provide support for the view that blobs are an evolutionary specialization of primate visual cortex that evolved only once, early in primate history. In other aspects of architectonic organization, area V1 of this Cheirogaleus individual closely resembles that of other strepsirhine primates, such as Galago. We were able to identify additional divisions of cortex in this individual, including the middle temporal visual area (MT), auditory cortex, and the primary somatosensory area (S1 or area 3b). These observations indicate that valuable neuroanatomical information can, in favorable cases, be obtained from rare mammalian species that die of natural causes in captivity or which must be euthanized, even though the animals have not been perfused.

ISSN:0006-8977    

DOI:10.1159/000113231

出版商:S. Karger AG    

年代:1996

数据来源: Karger