scholarly journals Reelin Mediates Hippocampal Cajal-Retzius Cell Positioning and Infrapyramidal Blade Morphogenesis

2019 ◽  
Author(s):  
Seungshin R Ha ◽  
Prem Tripathi ◽  
Ray Daza ◽  
Robert Hevner ◽  
David R Beier
Keyword(s):  
Dentate Gyrus ◽  
Cluster Formation ◽  
Intermediate Progenitors ◽  
Dividing Cells ◽  
Cell Positioning ◽  
Retzius Cell ◽  
Retzius Cells ◽  
Multiple Abnormalities ◽  
Direct Genetic Evidence ◽  
Neuron Layer

We have previously described hypomorphic reelin (Reln) mutant mice, RelnCTRdel, in which the morphology of the dentate gyrus is distinct from that seen in reeler mice. In the RelnCTRdel mutant the infrapyramidal blade of the dentate gyrus fails to extend, while the suprapyramidal blade forms with a relatively compact granule neuron layer. The distribution of Cajal-Retzius cells in the dentate gyrus was aberrant; Cajal-Retzius neurons were increased in the suprapyramidal blade, but were greatly reduced along the subpial surface of the prospective infrapyramidal blade. We also observed multiple abnormalities of the fimbriodentate junction. Firstly, progenitor cells were distributed abnormally; the neurogenic cluster at the fimbriodentate junction was absent, lacking the normal accumulation of Tbr2-positive intermediate progenitors. However, the number of dividing cells in the dentate gyrus was not generally decreased. Secondly, a defect of secondary glial scaffold formation, limited to the infrapyramidal blade, was observed. The densely radiating glial fibers characteristic of the normal fimbriodentate junction were absent in mutants. These fibers might be required for migration of progenitors, which may account for the failure of neurogenic cluster formation. These findings suggest the importance of the secondary scaffold and neurogenic cluster of the fimbriodentate junction in morphogenesis of the mammalian dentate gyrus. Our study provides direct genetic evidence showing that normal RELN function is required for Cajal-Retzius cell positioning in the dentate gyrus, and for formation of the fimbriodentate junction to promote infrapyramidal blade extension.

scholarly journals Reelin Mediates Hippocampal Cajal-Retzius Cell Positioning and Infrapyramidal Blade Morphogenesis

2020 ◽  
Vol 8 (3) ◽  
pp. 20
Author(s):  
Seungshin Ha ◽  
Prem P. Tripathi ◽  
Ray A. Daza ◽  
Robert F. Hevner ◽  
David R. Beier
Keyword(s):  
Dentate Gyrus ◽  
Cluster Formation ◽  
Intermediate Progenitors ◽  
Dividing Cells ◽  
Cell Positioning ◽  
Retzius Cell ◽  
Retzius Cells ◽  
Multiple Abnormalities ◽  
Direct Genetic Evidence ◽  
Neuron Layer

We have previously described hypomorphic reelin (Reln) mutant mice, RelnCTRdel, in which the morphology of the dentate gyrus is distinct from that seen in reeler mice. In the RelnCTRdel mutant, the infrapyramidal blade of the dentate gyrus fails to extend, while the suprapyramidal blade forms with a relatively compact granule neuron layer. Underlying this defect, we now report several developmental anomalies in the RelnCTRdel dentate gyrus. Most strikingly, the distribution of Cajal-Retzius cells was aberrant; Cajal-Retzius neurons were increased in the suprapyramidal blade, but were greatly reduced along the subpial surface of the prospective infrapyramidal blade. We also observed multiple abnormalities of the fimbriodentate junction. Firstly, progenitor cells were distributed abnormally; the “neurogenic cluster” at the fimbriodentate junction was absent, lacking the normal accumulation of Tbr2-positive intermediate progenitors. However, the number of dividing cells in the dentate gyrus was not generally decreased. Secondly, a defect of secondary glial scaffold formation, limited to the infrapyramidal blade, was observed. The densely radiating glial fibers characteristic of the normal fimbriodentate junction were absent in mutants. These fibers might be required for migration of progenitors, which may account for the failure of neurogenic cluster formation. These findings suggest the importance of the secondary scaffold and neurogenic cluster of the fimbriodentate junction in morphogenesis of the mammalian dentate gyrus. Our study provides direct genetic evidence showing that normal RELN function is required for Cajal-Retzius cell positioning in the dentate gyrus, and for formation of the fimbriodentate junction to promote infrapyramidal blade extension.

Cajal-Retzius Cells as Electrostatic Guides for Migrating Neurons

1976 ◽  
Vol 39 (2) ◽  
pp. 651-655 ◽  
Author(s):  
Michael A. Persinger ◽  
N. Ian Robb
Keyword(s):  
Molecular Layer ◽  
Pial Surface ◽  
Ventricular Surface ◽  
Cell Processes ◽  
Retzius Cell ◽  
Retzius Cells

A model is presented to explain one of the possible functions of the Cajal-Retzius cells which are known to mature perinatally but not to survive into late infantile life. In this model the processes of the Cajal-Retzius (C. R.) cells and the ventricular surface act as a transient capacitor-like mechanism during neural migration. Neurons which are connected to the ventricular surface during migration by an end foot are consequently guided by the Cajal-Retzius cell processes located in the upper strata of the cortical molecular layer. Once the end foot is severed migration stops and differentiation begins. When the period of migration nears completion postnatally, the mechanism is destroyed as these cells die or lose their connection with the cortical pial surface. Calculations are given to support the feasibility of this model.

scholarly journals Tbr2 Expression in Cajal-Retzius Cells and Intermediate Neuronal Progenitors Is Required for Morphogenesis of the Dentate Gyrus

2013 ◽  
Vol 33 (9) ◽  
pp. 4165-4180 ◽  
Author(s):  
R. D. Hodge ◽  
A. J. Garcia ◽  
G. E. Elsen ◽  
B. R. Nelson ◽  
K. E. Mussar ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Neuronal Progenitors ◽  
Retzius Cells

Modulatory Effects of Myomodulin on the Excitability and Membrane Currents in Retzius Cells of the Leech

1999 ◽  
Vol 82 (1) ◽  
pp. 216-225 ◽  
Author(s):  
Yong Wang ◽  
Judith A. Strong ◽  
Christie L. Sahley
Keyword(s):  
Action Potentials ◽  
Ionic Currents ◽  
Ionic Channels ◽  
Resting Membrane Potential ◽  
Cellular Mechanisms ◽  
Channel Modulation ◽  
Ion Channel Modulation ◽  
Thermal Sensing ◽  
Retzius Cell ◽  
Retzius Cells

Ion channel modulation by the peptide myomodulin (MM) has been demonstrated in a wide variety of organisms including Aplysia, Lymnaea, and Pleurobranchaea. This neural and muscular modulation has been shown to be important for shaping and modifying behavior. In this paper, we report that MM modulates several distinct ionic channels in another species, the medicinal leech Hirudo medicinalis. Experiments have focused on the Retzius cell (R) because the R cell is a multifunction neuron that has been implicated in a number of behaviors including feeding, swimming, secretion, thermal sensing, and the touch elicited shortening reflex and its plasticity. Previous work had identified a MM-like peptide in the leech and demonstrated that this peptide modulated the excitability of the R cell. Using combined current- and voltage-clamp techniques to examine the effects of MM on the R cell, we found that in response to a step pulse, MM increased the excitability of the R cell such that the cell fires more action potentials with a shorter latency to the first action potential. We found that this effect was mediated by the activation of a Na+-mediated inward current near the cell resting membrane potential. Second, we found that MM differentially modulated the potassium currents I A and I K. No effect of MM was found on I A, whereas MM significantly reduced both the peak and steady-state amplitudes of I Kby 49 ± 2.9% and 43 ± 7.2%, respectively (means ± SE). Finally we found that MM reduced the amplitude of the Ca2+ current by ∼20%. The ionic currents modulated by MM are consistent with the overall effect of MM on the cellular activity of the R cell. An understanding of the cellular mechanisms by which MM modulates the activity of the R cell should help us to better understand the roles of both MM and the R cell in a variety of behaviors in the leech.

scholarly journals Intermediate progenitors support migration of neural stem cells into dentate gyrus outer neurogenic niches

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Branden R Nelson ◽  
Rebecca D Hodge ◽  
Ray AM Daza ◽  
Prem Prakash Tripathi ◽  
Sebastian J Arnold ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Dentate Gyrus ◽  
Lineage Tracing ◽  
Cell Contact ◽  
Genetic Lineage ◽  
Multiphoton Imaging ◽  
Intermediate Progenitors ◽  
Dynamic Cell ◽  
Cell Cell

The hippocampal dentate gyrus (DG) is a unique brain region maintaining neural stem cells (NCSs) and neurogenesis into adulthood. We used multiphoton imaging to visualize genetically defined progenitor subpopulations in live slices across key stages of mouse DG development, testing decades old static models of DG formation with molecular identification, genetic-lineage tracing, and mutant analyses. We found novel progenitor migrations, timings, dynamic cell-cell interactions, signaling activities, and routes underlie mosaic DG formation. Intermediate progenitors (IPs, Tbr2+) pioneered migrations, supporting and guiding later emigrating NSCs (Sox9+) through multiple transient zones prior to converging at the nascent outer adult niche in a dynamic settling process, generating all prenatal and postnatal granule neurons in defined spatiotemporal order. IPs (Dll1+) extensively targeted contacts to mitotic NSCs (Notch active), revealing a substrate for cell-cell contact support during migrations, a developmental feature maintained in adults. Mouse DG formation shares conserved features of human neocortical expansion.

Positional Discrimination and re-development of Synapses in the Leech Whitmania Pigra

1990 ◽  
Vol 153 (1) ◽  
pp. 47-60
Author(s):  
REN-JI ZHANG ◽  
LIXIA ZHU ◽  
DAN-BING WANG ◽  
FAN ZHANG
Keyword(s):  
Receptive Field ◽  
Target Cell ◽  
Body Wall ◽  
Dorsal Side ◽  
The Body ◽  
Coupling Ratio ◽  
Retzius Cell ◽  
Retzius Cells ◽  
Normal Coupling ◽  
Whitmania Pigra

Identified neurones in the leech Whitmania pigra have a stable morphology with bilaterally symmetrical branching arborizations, and with axons on both sides arranged symmetrically in the connectives. Each anterior pagoda cell (AP) receives electrical and/or chemical synaptic input from mechanoreceptive cells on both sides of the body. The position in the body can be discriminated by the postsynaptic responses of the APs: as a rule, the responses to input from contralateral receptive neurones are stronger than those to input from ipsilateral ones, and the neurone with its receptive field on the dorsal side produces a stronger response than the neurone with a ventrally sited receptive field. APs integrate postsynaptic potentials and spikes. There are no connections between the two AP cells and so it is possible that positional discrimination depends upon a circuit comparing the inputs. After the body wall has been cut round and rotated by 180°, the mechanoreceptive cells and annular erector motoneurones reinnervate the body wall strictly according to their original orientation, and repair is bilaterally synchronous. This eliminates a role for target cell guidance, particularly in the adult leech. When an extra Retzius cell is implanted into cultured ganglia, synapses develop between the host and the implanted neurone. Such synapses generally show lower coupling ratios or PSP fluctuations. However, the specific electrical connection between the Retzius cells shows a normal coupling ratio.

scholarly journals Progesterone receptor expression in cajal-retzius cells of the developing rat dentate gyrus: Potential role in hippocampus-dependent memory

2018 ◽  
Vol 526 (14) ◽  
pp. 2285-2300
Author(s):  
Andrew J. Newell ◽  
Diana Lalitsasivimol ◽  
Jari Willing ◽  
Keith Gonzales ◽  
Elizabeth M. Waters ◽  
...  
Keyword(s):  
Progesterone Receptor ◽  
Dentate Gyrus ◽  
Potential Role ◽  
Receptor Expression ◽  
Progesterone Receptor Expression ◽  
Retzius Cells ◽  
Developing Rat ◽  
Hippocampus Dependent Memory

scholarly journals An increase in activity of serotonergic Retzius neurones may not be necessary for the consummatory phase of feeding in the leech Hirudo medicinalis.

1996 ◽  
Vol 199 (6) ◽  
pp. 1405-1414
Author(s):  
R J Wilson ◽  
W B Kristan ◽  
A L Kleinhaus
Keyword(s):  
Leydig Cells ◽  
Cell Activity ◽  
Sensory Stimulation ◽  
Firing Frequency ◽  
The Body ◽  
Spontaneous Movements ◽  
Tactile Stimuli ◽  
Retzius Cell ◽  
Retzius Cells ◽  
Increased Activity

During the consummatory phase of feeding, in which blood is ingested, medicinal leeches display a characteristic set of behaviours: they extend their jaws, are less responsive to sensory input, produce mucus, relax the body wall and exhibit waves of peristalsis that can run the length of the body. Earlier reports suggested that this pattern of behaviour is orchestrated by serotonin released from Retzius cells in response to the appropriate sensory stimulation of the lip. We have developed a semi-intact preparation in which only the nervous system in the posterior half of the leech was exposed. The front half of the leech was free to explore, bite through and feed until satiated from a blood-filled sausage casing while continuous intracellular and extracellular recordings were made from identified cells and the nerve roots of the exposed segments. Prior to attachment of the animal to the feeding device, the firing frequency of the Retzius cell increased transiently during spontaneous movements or tactile stimuli to its front or posterior end. In contrast, Retzius cell activity decreased after the anterior sucker attached to the membrane of the feeding device at about the time when ingestion was initiated. Increased activity of Leydig cells, which are known to modulate several circuits in the leech, was also associated with exploration. However, unlike that of Retzius cells, the activity of Leydig cells increased significantly following the onset of consumption. These results suggest that increased activity of Retzius cells in midbody ganglia is not a prerequisite for the consummatory phase of feeding and raises questions regarding the role of serotonin in regulating this behaviour.

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