The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

Schulze, Corinna; Schmidt‐Rhaesa, Andreas

doi:10.4081/jlimnol.2013.s1.e6

Cited by 19 publications

(62 citation statements)

References 38 publications

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“…The brain of H. dujardini is composed of two paired lobes (outer and inner) and one unpaired lobe (ventral). Outer and inner lobes have been identified in brains across Tardigrada [15,17,18,35,36]. The similar location of these brain structures across Tardigrada supports their direct homology in this lineage.…”

Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 67%

“…The tardigrade brain is composed of several lobes, which are at least party composed of neuronal somata [15,16,18,[35][36][37]. The brain of H. dujardini is composed of two paired lobes (outer and inner) and one unpaired lobe (ventral).…”

Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 99%

“…For instance, Zantke et al [35] did not identify ventral commissures in the ganglia of leg bearing segments of M. hufelandi. However, ventral commissures were identified in the ganglia of both heterotardigrade [18,36,37] and eutardigrade species [16,17], including M. harmsworthi [15], suggesting that ganglionic ventral commissures are ancestral for tardigrades. In this respect, H. dujardini appears to retain the ancestral condition.…”

Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 99%

“…Proponents of the protocerebral hypothesis have presented high-resolution confocal microscopy investigations of brain anatomy of two species of Macrobiotus (Eutardigrada) [15,35], Echiniscus testudo (Heterotardigrada) [36], Batillipes pennaki (Heterotardigrada) [37], and Actinarctus doryphorus ocellatus (Heterotardigrada) [37]. Proponents of the tripartite hypothesis have presented confocal microscopy investigations of Halobiotus crispae (Eutardigrada) [17] and Actinarctus doryphorus (Heterotardigrada) [18].…”

Section: Introductionmentioning

confidence: 99%

“…A subesophageal ganglion was included in the brain anatomy interpretations of several studies [13,17,18,20,34]. However, most recent studies of tardigrade brain anatomy have not identified a subesophogeal ganglion [15,[35][36][37]. In arthropods, the stomatogastric ganglion is innervated by the tritocerebrum [38].…”

Section: Introductionmentioning

confidence: 99%

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The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods

Smith

Jockusch

2014

Front Zool

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Introduction: Tardigrades are an ancient lineage of microinvertebrates with a unique metameric pattern consisting of a head and four lobopodal leg-bearing segments. While their close relationship to Onychophora and Arthropoda is well established, many questions remain about the structure and origin of the tardigrade metameric pattern. For example, the relationship of the tardigrade head to that of Arthropoda and Onychophora remains a contentious issue. One source of contention stems from disagreement about the structure of the tardigrade brain. The availability of developmental tools for the tardigrade Hypsibius dujardini give this species the potential to clarify questions regarding the relationship of tardigrade segmental patterns to those in Arthropoda and Onychophora. Here we investigate the nervous system, muscle system, and cuticle anatomy of H. dujardini using high-resolution microscopy methods. Results: We characterized nervous system anatomy of H. dujardini using a combination of anti-β -tubulin staining and DAPI staining and muscle system anatomy using phalloidin staining. We identified several brain lobes: paired outer lobes, paired inner lobes, and a single horseshoe-shaped ventral lobe. We also characterized similarities and differences in the nervous system and muscle system anatomy of the four body segments. Based on these, we detect distinct morphological identities for each segment in this species.

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Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 67%

Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 99%

Section: Nervous System Anatomy Of H Dujardini and Its Relationship mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods

Smith

Jockusch

2014

Front Zool

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Brain anatomy of the marine tardigrade actinarctus doryphorus (arthrotardigrada)

Persson

Halberg

Jørgensen

et al. 2013

Journal of Morphology

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Knowledge of tardigrade brain structure is important for resolving the phylogenetic relationships of Tardigrada. Here, we present new insight into the morphology of the brain in a marine arthrotardigrade, Actinarctus doryphorus, based on transmission electron microscopy, supported by scanning electron microscopy, conventional light microscopy as well as confocal laser scanning microscopy. Arthrotardigrades contain a large number of plesiomorphic characters and likely represent ancestral tardigrades. They often have segmented body outlines and each trunk segment, with its paired set of legs, may have up to five sensory appendages. Noticeably, the head carries numerous cephalic appendages that are structurally equivalent to the sensory appendages of the trunk segments. Our data reveal that the brain of A. doryphorus is partitioned into three paired lobes, and that these lobes exhibit a more pronounced separation as compared to that of eutardigrades. The first brain lobe in A. doryphorus is located anteriodorsally, with the second lobe just below it in an anterioventral position. Both of these two paired lobes are located anterior to the buccal tube. The third pair of brain lobes are situated posterioventrally to the first two lobes, and flank the buccal tube. In addition, A. doryphorus possesses a subpharyngeal ganglion, which is connected with the first of the four ventral trunk ganglia. The first and second brain lobes in A. doryphorus innervate the clavae and cirri of the head. The innervations of these structures indicate a homology between, respectively, the clavae and cirri of A. doryphorus and the temporalia and papilla cephalica of eutardigrades. The third brain lobes innervate the buccal lamella and the stylets as described for eutardigrades. Collectively, these findings suggest that the head region of extant tardigrades is the result of cephalization of multiple segments. Our results on the brain anatomy of Actinarctus doryphorus support the monophyly of Panarthropoda.

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Organization of the central nervous system and innervation of cephalic sensory structures in the water bear Echiniscus testudo (Tardigrada: Heterotardigrada) revisited

Gross

Epple

Mayer

2021

Journal of Morphology

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The tardigrade brain has been the topic of several neuroanatomical studies, as it is key to understanding the evolution of the central nervous systems in Panarthropoda (Tardigrada + Onychophora + Arthropoda). The gross morphology of the brain seems to be well conserved across tardigrades despite often disparate morphologies of their heads and cephalic sensory structures. As such, the general shape of the brain and its major connections to the rest of the central nervous system have been mapped out already by early tardigradologists. Despite subsequent investigations primarily based on transmission electron microscopy or immunohistochemistry, characterization of the different regions of the tardigrade brain has progressed relatively slowly and open questions remain. In an attempt to improve our understanding of different brain regions, we reinvestigated the central nervous system of the heterotardigrade Echiniscus testudo using anti‐synapsin and anti‐acetylated α‐tubulin immunohistochemistry in order to visualize the number and position of tracts, commissures, and neuropils. Our data revealed five major synapsin‐immunoreactive domains along the body: a large unitary, horseshoe‐shaped neuropil in the head and four neuropils in the trunk ganglia, supporting the hypothesis that the dorsal brain is serially homologous with the ventral trunk ganglia. At the same time, the pattern of anti‐synapsin and anti‐tubulin immunoreactivity differs between the ganglia, adding to the existing evidence that each of the four trunk ganglia is unique in its morphology. Anti‐tubulin labeling further revealed two commissures within the central brain neuropil, one of which is forked, and additional sets of extracerebral cephalic commissures associated with the stomodeal nervous system and the ventral cell cluster. Furthermore, our results showing the innervation of each of the cephalic sensilla in E. testudo support the homology of subsets of these structures with the sensory fields of eutardigrades.

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The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

Abstract: ABSTRACT

Cited by 19 publications

References 38 publications

The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods

The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods

Brain anatomy of the marine tardigrade actinarctus doryphorus (arthrotardigrada)

Organization of the central nervous system and innervation of cephalic sensory structures in the water bear Echiniscus testudo (Tardigrada: Heterotardigrada) revisited

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