Ventral Nerve Cord Transection in Crayfish: A Study of Functional Anatomy (original) (raw)
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Ultrastructural correlates of motor nerve regeneration in crayfish
Cell and Tissue Research, 1974
Identified motor neurons innervating distal limb muscles in the crayfish claw have been examined by light and electron microscopy after surgical interruption. The functionally competent distal segments of such axons, a few weeks after the operation, show enlarged glial sheaths that contain occasional small satellite axonal profiles (cf. Nordlander and Singer, 1972); evidence is presented that such profiles can arise
Molecular and Cellular Neuroscience, 2020
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Decerebration induced by surgical transection of cerebral ganglion of crayfish
International Journal of Research in Medical Sciences, 2020
Background: Since the neural structures of the crayfish brain closely resemble their equivalent in the mammals. This can be suggested by observing the similarity that exists in the brain divided by the surgical transection of the crayfish brain in which the protocerebrum remains attached to the first two cranial nerves, findings also described by Frederic Bremer in 1935 in cats with cerebral transection.Methods: Total 11 Adult male crayfish were trained to respond with defense reflex, the animals were placed in water at 0°C, remained without any movement, and subsequently through a small incision of 3 mm in diameter in the medial antero region and dorsal cephalothorax region, a surgical section of the cerebral ganglion was performed. Immediately after surgery, metal microelectrodes were implanted to collect the activity of the photoreceptors and visual fibers.Results: Once the defense reflex begins to recover in previously decerebrated crayfish, it means that it shows signs of recon...
Vascularization of the crayfish abdominal nerve cord
Journal of Comparative Physiology ? A, 1981
The anatomy of the vascular supply to the abdominal nerve cord of the crayfish Procambarus clarkii was investigated by filling the arterial supply with ink injected into the heart. The abdominal nerve cord was found to receive all of its blood supply from the ventral artery, which parallels the ventral midline of the nerve cord. Extensive vascularization of the abdominal nerve cord was revealed, with more major arterial inputs entering the ganglia than the connectives ). Both the neuronal somata and the neuropil are heavily vascularized . The connectives contained little of the fine vascularization found within the ganglia, and the roots were lightly and variably vascularized .
Degeneration and regeneration in crustacean peripheral nerves
Journal of Comparative Physiology, 1974
and physiological ( ) data from several crustacean species kept at 19-21~ show that isolated stumps of motor axons often survive intact for 150-250 days whereas sensory axonal segments usually degenerate within 20 days. Axonal segments of both motor and sensory axons that remain connected to their cell body generally remain functionally and morphologically normal after lesioning. No evidence was found for collatecal innervation of denervated muscles from intact motor neurons supplying nearby muscle masses, although the motor nerve terminals may not have completely degenerated. Evidence is presented that motor axons specifically re-innervate their original muscle mass if such re-innervation occurs within 90 days after lesioning. Regenerating sensory and motor fibers make appropriate CNS and peripheral connections so as to re-establish correctly a peripheral reflex found in intact animals .
Proceedings of the National Academy of Sciences, 1986
Axons in the larval sea lamprey can regenerate across the site of a spinal cord transection and form functioning synapses with some of their normal target neurons. The animals recover normal-appearing locomotion, but whether the regenerating axons and their synaptic connections are capable of playing a functional role during this behavior is unknown. To test this, "fictive" swimming was induced in the isolated spinal cord by the addition of D-glutamate to the bathing solution. Ventral root discharges of segments above and below a healed transection showed a high degree of phase-locking. This strongly suggests that the behavioral recovery is mediated by regenerated functional synaptic connections subserving intersegmental coordination of the central pattern generator for locomotion.
Neuroscience Letters, 1991
Glial nuclei have been reported to be incorporated into the axoplasm of surviving distal stumps (anucleate axons) weeks to months after lesioning abdominal motor axons in rock lobsters. We have not observed this phenomenon in crayfish medial giant axons (MGAs) which also survive for weeks to months after lesioning. Glial nuclei were not observed within MGAs perfused with a physiological intracellular saline. However, incorporation of glial nuclei was observed after MGAs were perfused with intracellular salines containing Fast green. From these and previously published data, we confirm that glial incorporation into axoplasm can occur, but we suggest that is is not a common mechanism used by crustaceans to provide for long-term survival of anucleate axons.
Brain, Behavior and Evolution, 2005
and 45 days after axotomy. These cells might share with glial cells the function of phagocytosis of cellular debris during the protocerebral tract degeneration. Quantitative analysis showed that the number of degenerating fi bers increased signifi cantly from 28 to 40 days after lesion, whereas the number of normal fi bers decreased accordingly. Measurements of cross-sectional areas of normal and degenerating axons showed that types II and III (medium) start to degenerate before type I (small). Type IV (large) axons do not degenerate, even after 40 days. Therefore, we can conclude that degeneration in these afferent fi bers starts late after axotomy, but proceeds at a faster rate afterwards until the complete degeneration of small and medium axons.
Experimental Neurology, 2003
The distributions of descending and ascending spinal projection neurons (i.e., spinal neurons with moderate to long axons) were compared in normal larval lamprey and in animals that had recovered for 8 weeks following a complete spinal cord transection at 50% body length (BL, normalized distance from the anterior head). In normal animals, application of HRP to the spinal cord at 60% BL (40% BL) labeled an average of 713.8 Ϯ 143.2 descending spinal projection neurons (718.4 Ϯ 108.0 ascending spinal projection neurons) along the rostral (caudal) spinal cord, most of which were unidentified neurons. Some of these neurons project for at least ϳ50 -60 spinal cord segments (ϳ36 -47 mm in animals with an average length of ϳ90 mm used in the present study). At 8 weeks posttransection, the numbers of HRP-labeled descending or ascending spinal neurons that extended their axons through the transection were about 40% of those in similar areas of the spinal cord in normal animals. Thus, in larval lamprey, axonal regeneration of descending and ascending spinal projection neurons is incomplete, similar to that found for descending brain neurons . The majority of restored projections were from unidentified spinal neurons that have not been documented previously. In contrast to results from several other lower vertebrates, in the lamprey ascending spinal neurons exhibited substantial axonal regeneration. Identified descending spinal neurons, such as lateral interneurons and crossed contralateral interneurons, and identified ascending spinal neurons, such as giant interneurons and edge cells, regenerated their axons at least 9 mm beyond the transection site in animals with an average length of ϳ90 mm, which is appreciably farther than previously reported. In contrast, most dorsal cells, which are centrally located sensory neurons, exhibited very little axonal regeneration.