The structure and function of the lateral line system in larvalXenopus laevis

The head of adult hagfishes (jawless craniates, Myxinoidea) of the family Eptatretidae displays a number of skin grooves of uncertain origin. These grooves have been homologized to the neuromast lines of other craniates, and they are innervated by two ganglionated cranial nerves that have been interpreted as lateral line nerves. The grooves do not, however, contain the compound receptors that are typical of a lateral line (i.e. neuromasts or electroreceptors), and both their development and function have remained enigmatic. To elucidate the embryonic origin of the grooves (which should develop from placodes if they are homologues of the lateral line system), embryos of Pacific hagfish were examined by means of threedimensional reconstructions from serial sections. Because of the scarcity of specimens of embryonic hagfishes, only two embryos were reconstructed, but these reconstructions clearly show that a number of placodes and placodal derivatives (i.e. sensory ridges, receptor primordia, and cranial ganglia) occur in the head of embryonic eptatretid hagfishes. Some of these placodes correspond to the lens and epibranchial placodes of other craniates, but there are also three other placodes which represent possible homologues of lateral line placodes. The topology of the placodes in this latter group corresponds to the topology of the grooves of adult hagfishes, and we therefore reach three conclusions: (i) that an embryonic lateral line system is present in hagfishes; (ii) that the grooves of adult hagfishes in all probability derive from lateral line placodes; and (iii) that the presence of lateral line placodes is a primitive character of craniates.

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Lateral line system

AccessScience ◽

10.1036/1097-8542.757316 ◽

2015 ◽

Keyword(s):

Lateral Line ◽

Lateral Line System ◽

Line System

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The lateral line system and its innervation in the Japanese eel Anguilla japonica (Teleostei: Elopomorpha: Anguillidae)

Journal of Morphology ◽

10.1002/jmor.21353 ◽

2021 ◽

Author(s):

Masanori Nakae ◽

Mari Kuroki ◽

Mao Sato ◽

Kunio Sasaki

Keyword(s):

Lateral Line ◽

Anguilla Japonica ◽

Japanese Eel ◽

Lateral Line System ◽

Line System

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Frequency response properties of primary afferent neurons in the posterior lateral line system of larval zebrafish

Journal of Neurophysiology ◽

10.1152/jn.00414.2014 ◽

2015 ◽

Vol 113 (2) ◽

pp. 657-668 ◽

Cited By ~ 9

Author(s):

Rafael Levi ◽

Otar Akanyeti ◽

Aleksander Ballo ◽

James C. Liao

Keyword(s):

Lateral Line ◽

Sine Wave ◽

Afferent Neuron ◽

Lateral Line System ◽

Afferent Neurons ◽

Primary Afferent Neurons ◽

Primary Afferent ◽

Line System ◽

Response Properties ◽

Larval Zebrafish

The ability of fishes to detect water flow with the neuromasts of their lateral line system depends on the physiology of afferent neurons as well as the hydrodynamic environment. Using larval zebrafish ( Danio rerio), we measured the basic response properties of primary afferent neurons to mechanical deflections of individual superficial neuromasts. We used two types of stimulation protocols. First, we used sine wave stimulation to characterize the response properties of the afferent neurons. The average frequency-response curve was flat across stimulation frequencies between 0 and 100 Hz, matching the filtering properties of a displacement detector. Spike rate increased asymptotically with frequency, and phase locking was maximal between 10 and 60 Hz. Second, we used pulse train stimulation to analyze the maximum spike rate capabilities. We found that afferent neurons could generate up to 80 spikes/s and could follow a pulse train stimulation rate of up to 40 pulses/s in a reliable and precise manner. Both sine wave and pulse stimulation protocols indicate that an afferent neuron can maintain their evoked activity for longer durations at low stimulation frequencies than at high frequencies. We found one type of afferent neuron based on spontaneous activity patterns and discovered a correlation between the level of spontaneous and evoked activity. Overall, our results establish the baseline response properties of lateral line primary afferent neurons in larval zebrafish, which is a crucial step in understanding how vertebrate mechanoreceptive systems sense and subsequently process information from the environment.

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Diversity and sexual dimorphism in the head lateral line system in North Sea populations of threespine sticklebacks, Gasterosteus aculeatus (Teleostei: Gasterosteidae)

Zoomorphology ◽

10.1007/s00435-020-00513-1 ◽

2020 ◽

Author(s):

Harald Ahnelt ◽

David Ramler ◽

Maria Ø. Madsen ◽

Lasse F. Jensen ◽

Sonja Windhager

Keyword(s):

Sexual Dimorphism ◽

North Sea ◽

Lateral Line ◽

Gasterosteus Aculeatus ◽

Sensory System ◽

Threespine Stickleback ◽

Lateral Line System ◽

Line System ◽

Marine Population ◽

Threespine Sticklebacks

AbstractThe mechanosensory lateral line of fishes is a flow sensing system and supports a number of behaviors, e.g. prey detection, schooling or position holding in water currents. Differences in the neuromast pattern of this sensory system reflect adaptation to divergent ecological constraints. The threespine stickleback, Gasterosteus aculeatus, is known for its ecological plasticity resulting in three major ecotypes, a marine type, a migrating anadromous type and a resident freshwater type. We provide the first comparative study of the pattern of the head lateral line system of North Sea populations representing these three ecotypes including a brackish spawning population. We found no distinct difference in the pattern of the head lateral line system between the three ecotypes but significant differences in neuromast numbers. The anadromous and the brackish populations had distinctly less neuromasts than their freshwater and marine conspecifics. This difference in neuromast number between marine and anadromous threespine stickleback points to differences in swimming behavior. We also found sexual dimorphism in neuromast number with males having more neuromasts than females in the anadromous, brackish and the freshwater populations. But no such dimorphism occurred in the marine population. Our results suggest that the head lateral line of the three ecotypes is under divergent hydrodynamic constraints. Additionally, sexual dimorphism points to divergent niche partitioning of males and females in the anadromous and freshwater but not in the marine populations. Our findings imply careful sampling as an important prerequisite to discern especially between anadromous and marine threespine sticklebacks.

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