scholarly journals 3D reconstruction of odontoblast processes of the mouse molar and incisor

2020 ◽  
Author(s):  
Ninna Shuhaibar ◽  
Arthur R. Hand ◽  
Mark Terasaki
Keyword(s):  
Tooth Development ◽  
Three Dimensional ◽  
Continuous Growth ◽  
Average Ratio ◽  
Section Electron ◽  
Labial Side ◽  
Serial Section Electron Microscopy ◽  
Plate Geometry ◽  
Odontoblast Processes ◽  
Insight Into

AbstractOdontoblast processes are thin cytoplasmic projections that extend from the cell body at the periphery of the pulp toward the dentin-enamel junction. The odontoblast processes function in the secretion and assembly of dentin during development, participate in mechanosensation, and aid in dentin repair in mature teeth. Because they are small and densely arranged, their three-dimensional organization is not well documented. To gain further insight into how odontoblast processes contribute to odontogenesis, we used serial section electron microscopy to examine these processes in the predentin region of mouse molars and incisors. In molars, the odontoblast processes are tubular with a diameter of ~1.8 μm. The odontoblast processes near the incisor tip are similarly shaped, but those midway between the tip and apex are shaped like plates. The plates are radially aligned and longitudinally oriented with respect to the growth axis of the incisor. The thickness of the plates is approximately the same as the diameter of molar odontoblast processes. The plates have an irregular edge; the average ratio of width (midway in the predentin) to thickness is 2.3 on the labial side and 3.6 on the lingual side. The plate geometry seems likely to be related to the continuous growth of the incisor and may provide a clue as to the mechanisms by which the odontoblast processes are involved in tooth development.

scholarly journals Centriolar remodeling underlies basal body maturation during ciliogenesis in Caenorhabditis elegans

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Inna V Nechipurenko ◽  
Cristina Berciu ◽  
Piali Sengupta ◽  
Daniela Nicastro
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Sensory Neurons ◽  
Basal Body ◽  
Three Dimensional ◽  
C Elegans ◽  
Mother Centriole ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

The primary cilium is nucleated by the mother centriole-derived basal body (BB) via as yet poorly characterized mechanisms. BBs have been reported to degenerate following ciliogenesis in the C. elegans embryo, although neither BB architecture nor early ciliogenesis steps have been described in this organism. In a previous study (Doroquez et al., 2014), we described the three-dimensional morphologies of sensory neuron cilia in adult C. elegans hermaphrodites at high resolution. Here, we use serial section electron microscopy and tomography of staged C. elegans embryos to demonstrate that BBs remodel to support ciliogenesis in a subset of sensory neurons. We show that centriolar singlet microtubules are converted into BB doublets which subsequently grow asynchronously to template the ciliary axoneme, visualize degeneration of the centriole core, and define the developmental stage at which the transition zone is established. Our work provides a framework for future investigations into the mechanisms underlying BB remodeling.

scholarly journals Astrocytes refine cortical connectivity at dendritic spines

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
W Christopher Risher ◽  
Sagar Patel ◽  
Il Hwan Kim ◽  
Akiyoshi Uezu ◽  
Srishti Bhagat ◽  
...  
Keyword(s):  
Dendritic Spines ◽  
Cortical Neurons ◽  
Three Dimensional ◽  
Early Postnatal Development ◽  
Mouse Cortex ◽  
Section Electron ◽  
Refinement Process ◽  
Serial Section Electron Microscopy ◽  
Cortical Inputs ◽  
The Brain

During cortical synaptic development, thalamic axons must establish synaptic connections despite the presence of the more abundant intracortical projections. How thalamocortical synapses are formed and maintained in this competitive environment is unknown. Here, we show that astrocyte-secreted protein hevin is required for normal thalamocortical synaptic connectivity in the mouse cortex. Absence of hevin results in a profound, long-lasting reduction in thalamocortical synapses accompanied by a transient increase in intracortical excitatory connections. Three-dimensional reconstructions of cortical neurons from serial section electron microscopy (ssEM) revealed that, during early postnatal development, dendritic spines often receive multiple excitatory inputs. Immuno-EM and confocal analyses revealed that majority of the spines with multiple excitatory contacts (SMECs) receive simultaneous thalamic and cortical inputs. Proportion of SMECs diminishes as the brain develops, but SMECs remain abundant in Hevin-null mice. These findings reveal that, through secretion of hevin, astrocytes control an important developmental synaptic refinement process at dendritic spines.

scholarly journals Three-dimensional organization of transzonal projections and other cytoplasmic extensions in mouse ovarian follicles

2018 ◽  
Author(s):  
Valentina Baena ◽  
Mark Terasaki
Keyword(s):  
Granulosa Cells ◽  
Ovarian Follicle ◽  
Cumulus Cell ◽  
Three Dimensional ◽  
Cumulus Cells ◽  
Ovarian Follicles ◽  
New Methods ◽  
Section Electron ◽  
Paracrine Interaction ◽  
Serial Section Electron Microscopy

AbstractEach mammalian oocyte is nurtured by its own multi-cellular structure, the ovarian follicle. We used new methods for serial section electron microscopy to examine entire cells and their projections in mouse antral ovarian follicles. It is already known that cumulus cells send towards the oocyte thin cytoplasmic projections called transzonal projections (TZPs), which are crucial for normal oocyte development. We found that most TZPs do not reach the oocyte, and that they often branch and make gap junctions with each other. Furthermore, the connected TZPs are usually contacted on their shaft by oocyte microvilli. Mural granulosa cells were found to possess randomly oriented cytoplasmic projections that are strikingly similar to free-ended TZPs. We propose that granulosa cells use cytoplasmic projections to search for the oocyte, and cumulus cell differentiation results from a contact-mediated paracrine interaction with the oocyte.

Three-Dimensional Reconstruction of the Amphid Sensory Primary Cilia of C. elegans by Serial Section Electron Microscopy

2012 ◽  
Vol 18 (S2) ◽  
pp. 538-539
Author(s):  
C. Berciu ◽  
D. Nicastro ◽  
D.B. Doroquez ◽  
P. Sengupta
Keyword(s):  
Electron Microscopy ◽  
Serial Section ◽  
Primary Cilia ◽  
Three Dimensional ◽  
Three Dimensional Reconstruction ◽  
C Elegans ◽  
Dimensional Reconstruction ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Three-dimensional structure of dendritic spines, neuronal specializations that impart both stability and flexibility to synaptic function

1993 ◽  
Vol 51 ◽  
pp. 92-93
Author(s):  
Kristen M. Harris
Keyword(s):  
Dendritic Spines ◽  
Three Dimensional ◽  
Synaptic Function ◽  
Dimensional Structure ◽  
Excitatory Synapses ◽  
Concept Of Function ◽  
Section Electron ◽  
High Quality Information ◽  
The Central Nervous System ◽  
Mathematical Analyses

Dendritic spines are the tiny protrusions that stud the surface of many neurons and they are the location of over 90% of all excitatory synapses that occur in the central nervous system. Their small size and variable shapes has in large part made detailed study of their structure refractory to conventional light microscopy and single section electron microscopy (EM). Yet their widespread occurrence and likely involvement in learning and memory has motivated extensive efforts to obtain quantitative descriptions of spines in both steady state and dynamic conditions. Since the seminal mathematical analyses of D’Arcy Thompson, the power of establishing quantitatively key parameters of structure has become recognized as a foundation of successful biological inquiry. For dendritic spines highly precise determinations of structure and its variation are proving themselves as the kingpin for establishing a valid concept of function. The recent conjunction of high quality information about the structure, function, and theoretical implications of dendritic spines has produced a flurry of new considerations of their role in synaptic transmission.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

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