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PubMed1991

Postembedding immunocytochemistry for GABA and glycine reveals the synaptic relationships of the dopaminergic amacrine cell of the cat retina.

Postembedding electron microscope immunocytochemistry of glycine and GABA conjugated to colloidal gold has been applied to pre-embedded cat retina stained with the antibody against tyrosine hydroxylase (Toh+). Toh+ stained cells are the equivalent of A18 amacrine cells of Golgi descriptions (Kolb et al., '81). The dendrites of Toh+ cells synapse upon several different types of glycine-positive amacrine cell bodies. We suggest that these are the A8, A3/A4, and AII amacrine cell varieties by analogous immunocytochemical staining intensity, to glycine autoradiographic labeling intensity (Pourcho and Goebel, '85). The greatest number of synapses from Toh+ dendrites are directed at the least glycine-positive amacrine, which is the AII cell by all morphological criteria. A few glycine-positive profiles are also presynapatic to the Toh+ stained cell body itself. Toh+ profiles are also presynaptic to GABA-positive amacrine cell bodies. The commonest amacrine synapsed upon is very heavily labeled with GABA immunocytochemistry. We consider it to be the A17 amacrine cell, which is known to label strongly by [3H] muscimol autoradiography (Pourcho and Goebel, '83). The cell body of the Toh+ amacrine cell also receives many synapses, which appear to be GABA-positive, and Toh+ profiles running in stratum 1 of the inner plexiform layer (IPL) are both pre- and postsynaptic to GABA-positive amacrine cell profiles. In addition, the cell body and primary dendrites of the Toh+ cell receive input from a bipolar type and GABA- or glycine-negative profiles. GABA-positive profiles, belonging to the interplexiform cell (IPC), are synapsed upon by Toh+ profiles that run in the outer plexiform layer (OPL).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Immunocytochemical localization of the alpha 1 and beta 2/3 subunits of the GABAA receptor in relation to specific GABAergic synapses in the dentate gyrus.

Dentate granule cells receive spatially segregated GABAergic innervation from at least five types of local circuit neurons, and express mRNA for at least 11 subunits of the GABAA receptor. At most two to four different subunits are required to make a functional pentamer, raising the possibility that cells have on their surface several types of GABAA receptor channel, which may not be uniformly distributed. In order to establish the subcellular location of GABAA receptors on different parts of dentate neurons, the distribution of immunoreactivity for the alpha 1 and beta 2/3 subunits of the receptor was studied using high-resolution immunocytochemistry. Light microscopic immunoperoxidase reactions revealed strong GABAA receptor immunoreactivity in the molecular layer of the dentate gyrus. Pre-embedding immunogold localization of the alpha 1 and beta 2/3 subunits consistently showed extrasynaptic location of the GABAA receptor on the somatic, dendritic and axon initial segment membrane of granule cells, but failed to show receptors in synaptic junctions. Using a postembedding immunogold technique on freeze-substituted, Lowicryl-embedded tissue, synaptic enrichment of immunoreactivity for these subunits was found on both granule and non-principal cells. Only the postembedding immunogold method is suitable for revealing relative differences in receptor density at the subcellular level, giving approximately 20 nm resolution. The immunolabelling for GABAA receptor occupied the whole width of synaptic junctions, with a sharp decrease in labelling at the edge of the synaptic membrane specialization. Both subunits have been localized in the synaptic junctions between basket cell terminals and somata, and between axo-axonic cell terminals and axon initial segments of granule cells, with no qualitative difference in labelling. Receptor-immunopositive synapses were found at all depths of the molecular layer. Some of the boutons forming these dendritic synapses have been shown to contain GABA, providing evidence that some of the GABAergic cells that terminate only on the dendrites of granule cells also act through GABAA receptors. Double immunolabelling experiments demonstrated that a population of GABA-immunopositive neurons expresses a higher density of immunoreactive GABAA receptor on their surface than principal cells. Interneurons were found to receive GABAA receptor-positive synapses on their dendrites in the hilus, molecular and granule cell layers. Receptor-immunopositive synapses were also present throughout the hilus on presumed mossy cells. The results demonstrate that both granule cells and interneurons exhibit a compartmentalized distribution of the GABAA receptor on their surface, the postjunctional membrane to GABAergic terminals having the highest concentration of receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1999

Neuropathologic effects of phenylmethylsulfonyl fluoride (PMSF)-induced promotion and protection in organophosphorus ester-induced delayed neuropathy (OPIDN) in hens.

The serine/cysteine protease inhibitor phenylmethylsulfonyl fluoride (PMSF) has been used both to promote and to protect against neuropathic events of organophosphorus-induced delayed neuropathy (OPIDN) in hens (Veronesi and Padilla, 1985; Pope and Padilla, 1990; Lotti et al., 1991; Pope et al., 1993; Randall et al., 1997). This study is the first to expand upon this work by using high resolution microscopy provided by epoxy resin embedding and thin sectioning to evaluate neuropathological manifestations of promotion and protection, and to correlate them with associated clinical modifications. To evaluate dose-related effects of OPIDN, single phenyl saligenin phosphate (PSP) dosages of 0.5, 1.0, or 2.5 mg/kg were administered to adult hens. PMSF (90 mg/kg) was given either 4 hours after (for promotion) or 12 hours prior to (for protection) PSP administration. Clinical signs and pathologic changes in the biventer cervicis nerve, which is uniquely sensitive to OPIDN (El-Fawal et al., 1988), were monitored. PSP alone, 2.5 mg/kg, caused severe OPIDN (terminal clinical score 7.5 +/- 1.0 [0-8 scale]; neuropathology score 2.7 +/- 0.3 [0-4 scale, based on myelinated fiber degeneration]). PMSF given 12 hours prior to PSP gave complete protection (clinical and neuropathology scores of 0; p<0.0001 compared to PSP alone). Signs and lesions of OPIDN were absent following 0.5 mg/kg PSP alone, but PMSF given 4 hours after PSP potentiated its neurotoxic effects (all hens had clinical scores of 4.0 and the average neuropathology score was 3.5 +/- 0.3; p<0.0001 compared to PSP alone). Although quantitative differences were noted, qualitative differences among nerves from hens with OPIDN were not evident, either with light or electron microscopy. At the time of sacrifice, there was a statistically linear relationship (r2 = 0.76) between the clinical scores on the last day of observation and the neuropathology scores (p<0.0001). This study demonstrates that the degree of peripheral nerve myelinated fiber degeneration correlates with clinical deficits in PMSF-induced potentiation of and protection against OPIDN.

Animals↗
PubMed1996

Distribution of lectin binding sites in human bone marrow. Identification by use of an ultrastructural postembedding technique.

The purpose of this ultrastructural study was to detect various carbohydrate residues on mature elements of the major human haematopoietic cell lines (granulopoiesis, erythropoiesis and megakaryopoiesis), sinus endothelium and plasma cells under comparable experimental conditions. Marrow specimens were processed according to a modified postembedding technique with Unicryl as embedding resin. A broad panel of 10 digoxigenin (dig)-conjugated lectins was applied for staining and specificity was evaluated by incubation with their corresponding inhibitory sugars. Lectins under study were derived from Canavalia ensiformis (Con A), Triticum vulgare (WGA), Ulex europaeus-I (UEA-I), Baubinia purpurea (BPA), Erythrina cristagalli (ECA), Glycine max (SBA), Helix pomatia (HPA), Arachis hypogaea (PNA), Griffonia simplicifolia-I (GS-I) and its isotype GS-I-B4. As a common feature WGA was shown to be a prominent marker of cytoplasmic membranes, except for plasma cells. On the other hand, Con A turned out to be reactive with the nuclear envelopes in all haematopoietic cells and, additionally, exhibited a strong labelling of the rough endoplasmic reticulum in plasma cells. Granules of eosinophilic granulocytes revealed staining of varying intensity with all lectins; however, inhibition was mostly incomplete. Several lectins (WGA, Con A, UEA, BPA, ECA, SBA and PNA) disclosed a clear cut differentiation of at least two subpopulations of granules in polymorphonuclear leukocytes. UEA-I (H type 2 specific) exhibited a high affinity to cytoplasmic membranes of erythropoietic precursor cells. In keeping with the blood group of our patient (O Rh+) membranes of red blood cells were completely negative with those lectins that are known to exhibit a group A or B specificity (HPA, GS-I-B4). As a remarkable finding the luminal and abluminal surfaces of sinusoidal endothelium revealed a specific reaction with UEA-I. Carbohydrate binding sites on the surface of endothelial cells may play a pivotal role in several functional processes such as cellular adhesion, traffic of mature cell elements across the marrow blood barrier and "homing' of haematopoietic stem cells.

Bone Marrow↗
PubMed2002

A three-dimensional study of brain string vessels using celloidin sections stained with anti-collagen antibodies.

The purpose of this study was to explain the morphology and significance of string vessels in human brains. Brain slices (1.5 cm thick) were embedded in celloidin, sections cut at 100 microm and stained with antibody to collagen IV. A second component of the study was a 3-D rotational study for which we used sections stained with propidium iodide for cell nuclei and anti-collagen stain for blood vessel basement membranes. The materials consisted of brain from two infants at 28 and 35 weeks gestation, two term infants at 20 days and 3 months, one 5 years old, and 3 adults aged 25, 57, and 84 years. String vessels were counted in at least six fields of deep white matter using a 10x objective and the counts averaged and expressed as string vessels per cubic mm. The 3-D rotational study using confocal microscopy was designed to find nuclei in string vessels. The least number of string vessels were present in the premature infant. All others had comparably similar numbers of string vessels except the two term-born infants in whom there was a 3-5-fold increase. However, the two brains had other pathologic lesions, which could affect the counts. In normal brains, string vessels appear as a singe line of stain and usually connect two arterioles or capillaries. They can form loops and occasionally a string vessel may continue into a normal capillary. String vessels have rare nuclei. Our study indicates that string vessels are present in utero, increase in number and are present throughout life. Their exact nature remains unexplained. They apparently do not represent age-related acquired atrophy of capillaries because they are present at all ages and do not progressively increase with normal aging. This technique appears suitable for the study of large number of string vessels.

Adult↗
PubMedDate not supplied

Cytoarchitectonic definition of prefrontal areas in the normal human cortex: I. Remapping of areas 9 and 46 using quantitative criteria.

The classical cytoarchitectonic maps of human prefrontal areas produced by various cartographers in the early part of this century, though similar in gross topography, differ from one another in their descriptions of the size, shape, and precise location of specific regions within the frontal promontory. The current advances in human neurobiology stimulated us to reinvestigate the cytoarchitecture of the human prefrontal cortex, beginning with areas 9 and 46, to establish a set of objective cytometric criteria for identification of these areas. Nisslstained and Gallyas-stained celloidin-embedded sections were prepared from the left hemispheres of 17 human subjects 23-73 years old, without history of neurological disease. In eight cases, light microscopic observations were supplemented by morphometric data collected on a research microscope equipped with differential interference contrast optics and interfaced to a TV monitor with video mixing equipment and a microcomputer. We used the three-dimensional counting method of Williams and Rakic (1988) to measure (1) total cortical and relative laminar thickness, (2) neuronal packing density per 0.001 mm3 in individual cortical layers, and (3) sizes of neuronal somata in selected cortical layers. Light microscopic analysis confirmed that the cortical layers are more differentiated in area 46 than in area 9, particularly at the borders of layer IV. Layers III and V exhibit clearer sublamination in area 9, while layer IV is also somewhat wider in area 46 than in area 9 (9.3% vs 6.4% of cortical thickness); the overall thickness of the cortex is the same in both areas. Cytometric analysis revealed that layer IV neurons of area 46 are more densely packed than those in area 9 (55.38 +/- 7.26 vs 45.80 +/- 4.45 neurons/0.001 mm3), as are neurons in the supragranular layers II and III combined (53.51 +/ 6.33 vs 45.69 +/ 3.81 neurons/0.001 mm3). Finally, neurons in area 46 are more homogeneous in size than those in area 9. Differences in myeloarchitecture are also evident: each area contains numerous, well-stained radial striae and two pronounced bands of horizontal fibers, but in general, area 46 is less myelinated than area 9. Objective cytometric methods can clearly distinguish two adjacent areas within the human prefrontal lobe. These findings may prove useful in the areal parcellation of the human cerebral cortex as well as provide a baseline for analysis of pathological changes in neurological and psychiatric disorders such as a schizophrenia, Huntington's or Alzheimer's diseases.

Adult↗
PubMed1987

Light microscopic evidence of hair cell regeneration after gentamicin toxicity in chick cochlea.

This study examines the temporal pattern of hair cell loss in the chick basilar papilla following ten days of gentamicin administration in hatchling chicks. Chicks were subsequently killed at ages 11, 18, 25, and 32 days. The basilar papillae were embedded in plastic and serially sectioned for light microscopic analysis. Hair cell counts were obtained at 100-microM intervals throughout the length of the papilla. Significant hair cell loss was documented basally in the 11-day-old chicks, and spread apically over time to maximal loss in the 18-day-old animals. Relative to the control chicks, there was a 36% hair cell loss in these animals. Interestingly, there appears to be a progressive partial recovery of the normal hair cell counts in the 25- and 32-day-old animals.

Animals↗
PubMed1996

Ultrastructure of the stomatogastric ganglion neuropil of the crab, Cancer borealis.

The stomatogastric ganglion (STG) of the crab, Cancer borealis, contains the neural networks responsible for rhythmic pattern generation of the foregut. Neuron counts indicate that the STG of C. borealis has 25-26 neurons, 4-5 fewer than that found in lobsters. We describe the ultrastructural features of the ganglion by focusing on those that may be involved in storage, release, or range of action of peptide modulators, including a lacunar system and multiple types of intercellular junctions. In the neuropil, we identify five synaptic profile classes that contain the invertebrate presynaptic apparatus (dense bars, small clear vesicles), two of which also contain dense core (modulator-containing) vesicles. These latter two are comprised of multiple immunocytochemical classes that are not easily distinguished by structural criteria. In addition, we find neurohemal-like profiles that contain primarily dense core vesicles. Our finding that multiple profile types in the STG possess modulator-containing vesicles coincides with immunocytochemical results better than do previous ultrastructural studies that report only one such profile type. We show that a single modulatory input, stomatogastric nerve axon 1, makes only classical synapses and not neurohemal-like profiles, although some modulators are found in both these profile types. These data provide the groundwork for understanding the architecture of modulatory input-target interactions and suggest ways that the specificity of modulatory effects within a complex neuropil may be attained.

Animals↗
PubMed1996

Sectional anatomy of connective tissue structures in the hindfoot of the newborn child and the adult.

BACKGROUND: The knowledge of the normal anatomy of the newborn hindfoot is essential for the understanding of foot deformities. In the present study, we investigated tendons, ligaments, and soft tissue structures in the newborn foot. METHODS: The sectional anatomy of eight newborn feet was studied in 300-500-microns-thick sections processed by plastination histology. For comparison, 3-5-mm-thick plastinated sheets of adult feet were investigated. RESULTS: Our specimens show obvious differences of the newborn compared with the adult foot. In the subcutaneous adipose tissue, the heel pad and the fat pad of the Achilles tendon and the relative size and topography of adipose tissue pads are different. Moreover, the course of the flexor hallucis tendon and the insertion pattern of the Achilles tendon are distinct. Finally, there are differences in the course and in the relative length of some plantar ligaments. CONCLUSIONS: Our data reveal that the differences between the newborn foot and the adult foot result mainly from the different shape and position of the tarsal bones. Our findings are of clinical importance for the evaluation of magnetic resonance imaging in the normal infant's foot and in foot deformities.

Aged↗
PubMed1998

Synaptic coexistence of AMPA and NMDA receptors in the rat hippocampus: a postembedding immunogold study.

Synaptic distributions of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) receptor subunits, NMDAR1 and GluR2, respectively, were examined by electron microscopy with the high spatial resolution of postembedding immunogold localization. We provide direct evidence for colocalization at individual axodendritic asymmetric synapses within the CA1 subfield of rat hippocampus. AMPA/NMDA receptor colocalization was found both in gamma-aminobutyric acid (GABA)ergic dendrites and non-GABAergic dendritic shafts, as well as dendritic spines. Some asymmetric synapses were found to contain only NMDAR1 or GluR2; however, most immunopositive synapses contained both subunits. Many NMDAR1 and/or GluR2 immunopositive profiles received GABAergic innervation at an adjacent synapse, providing a substrate for GABAergic modulation of both GluR classes. These data suggest that excitatory neuronal transmission in CA1 neurons may generally involve activation of both NMDA and AMPA receptor subunits at a single synapse, however, they also offer ultrastructural evidence for NMDAR1-only synapses that might represent silent synapses.

Animals↗
PubMed1998

Sensory innervation of the suprarenal gland in the albino rat: a fluorescent tract tracer study.

The afferent innervation of the suprarenal gland was studied by using a fluorescent tract tracer in the adult albino rat. The left suprarenal gland was injected slowly with 5 microl of 2% aqueous suspension of Fast blue. After a survival period of 4-5 days, the dorsal root ganglia were dissected out and 15-microm-thick plastic (JB 4) sections were examined under the fluorescent microscope. The labelled neurons were seen from the third thoracic to second lumbar dorsal root ganglia, ipsilateral to the site of injection with maximum concentration from T6 to T11. These primary sensory neurons were round to oval in shape, varied from 7 microm to 40 microm in size, and were distributed randomly in the dorsal root ganglia. The labelling of the primary sensory neurons in the dorsal root ganglia confirms the presence of sensory nerve endings in the suprarenal gland that may be responsible for the vascular distension and hormonal release.

Adrenal Glands↗
PubMed2000

Cerebral microvascular architecture in the common tree shrew (Tupaia glis) revealed by plastic corrosion casts.

The vascularization of the cerebrum (cerebral cortex and basal ganglia) in the common tree shrew (Tupaia glis) has been studied in detail using vinyl injection and vascular corrosion cast/SEM techniques. It is found that the arterial supply of the cerebral cortex are from cortical branches of the middle cerebral artery (MCA) and of the anterior cerebral artery (ACA). These arteries are in turn branches of the internal carotid artery (ICA). In addition, the cerebral cortex receives the blood from the cortical branches of the posterior cerebral artery (PCA) that originates from the basilar artery (BA). These cortical arteries gives rise to rectilinear orientated intracortical arteries that are divided into dense capillary networks to supply the cerebral cortex. The capillary networks drain the blood into intracortical veins and then into the tributaries of major superficial cerebral veins. The basal ganglia (caudate and lentiform nuclei) are supplied by central or perforating branches of the ACA and MCA. These central or medullary arteries give rise to arterioles that ramify into dense capillary plexuses. The venous blood from both nuclei drains into venules and finally into the tributaries of internal cerebral veins. It is obvious that on the ventral aspect, the diameter of the lateral striate artery (LSA) and of the penetrating arterioles from the MCA are much smaller than that of the MCA. These arterioles have few side branches while the peripheral branches of the superficial cerebral arteries exhibit several series of branches that are gradually reduced in diameter before branching into intracortical arteries. This could be one of the reasons why the rupture of cerebral arteries in man mostly occurs in the those originating from the ventral surface rather than from the dorsolateral surface.

Animals↗
PubMed1990

Macrophage mobilization and morphology during lens regeneration from the iris epithelium in newts: studies with correlated scanning and transmission electron microscopy.

The lens was removed from both eyes of adult newts (Notophthalmus viridescens), and the eyes were fixed in Karnovsky's fixative every 2 days 0-20 days after operation. Anterior half-eyes were prepared by standard procedures for scanning electron microscopy of the surface. Before fixation, the posterior iris surface was cleaned of adhering vitreous mechanically with forceps or by treatment with bovine testicular hyaluronidase or with hyaluronidase and collagenase. Some specimens were cryofractured in buffer or ethanol transverse to the mid-dorsal iris, and the fractured surface viewed with scanning electron microscopy (SEM). Cells with various combinations of ridges, blebs, filopodia, and lamellipodia were observed adhering to the posterior surface of the iris by 6 days after lentectomy. These cells, which exhibited the surface characteristics of macrophages, became more numerous in specimens fixed after longer intervals. Invasion of the iris epithelium was observed in a cryofractured specimen. After observations with SEM, selected specimens were embedded in plastic and sectioned for study with transmission electron microscopy (TEM). The cells on the iris surface had the cytological characteristics of macrophages, and other macrophages were located within the iris epithelium. In specimens fixed 16 or more days after lentectomy, a bulging lens vesicle was regenerating from the dorsal pupillary margin of the iris. Macrophages were absent or few on the surface of this developing lens but remained scattered over the adjoining iris. Roles that might be played by these macrophages during the transdifferentiation of iris epithelium into lens are discussed.

Animals↗
PubMed1980

Aspartame administration to the infant monkey: hypothalamic morphology and plasma amino acid levels.

Infant monkeys received 2 gm/kg body weight of aspartame (APM) or 2 gm/kg body weight APM plus 1 gm/kg body weight monosodium glutamate (MSG) by gastric tube. Blood samples were obtained at intervals over the ensuing 4 hours and analyzed for amino acid levels. At this time, each infant was perfused with glutaraldehyde. The hypothalamus was embedded in plastic and then serially sectioned at 1 mu. Hypothalamic morphology was normal in all eight infants given 2 gm/kg body weight APM and in the six infants given 2 gm/kg body weight APM plus 1 gm/kg body weight MSG. By light microscopy, no pycnotic nuclei, neuronal degeneration, or dendritic swelling was noted. In both experimental and control brains, localized areas of poor perfusion exhibited abnormal morphology. Elevated plasma levels of aspartate, glutamate, and phenylalanine indicated that the test compounds were administered and absorbed. Variable rates of absorption were evident, probably due to the necessity of administering APM as a slurry, due to its low solubility. On the basis of blood absorption curves, it appears that infant monkeys metabolize aspartate and glutamate and phenylalanine somewhat more rapidly than man. It is concluded that APM given alone or with MSG, in large acute doses, does not result in hypothalamic damage in the newborn monkey.

Amino Acids↗
PubMed1984

Quantitative changes in the morphology of the aging canine prostate.

Stereological methods at the light and electron microscopic levels were used to examine the morphological changes in the beagle prostate associated with increasing age and with the occurrence of spontaneous benign hyperplasia. Analyses of semithin sections of tissue embedded in plastic revealed that proliferation of prostatic glandular and stromal components, increase in epithelial cell numbers, and increase in epithelial cell size all contributed to the dramatic increase in prostate weight seen in aging dogs. Analyses at the electron microscopic level revealed that the volume densities of rough endoplasmic reticulum and secretion granules were significantly lower in epithelial cells of the immature prostate than in the prostate of mature dogs (greater than 1.5 years of age). In contrast, no significant differences were seen in the volume densities of rough endoplasmic reticulum, free ribosomes, secretion granules, smooth endoplasmic reticulum, or mitochondria in randomly selected prostatic epithelial cells of dogs 1.5 to 9 years of age, whether or not the prostates were hyperplastic.

Aging↗
PubMed1985

Cellular and subcellular colocalization of nerve growth factor and epidermal growth factor in mouse submandibular glands.

Immunocytochemical methods have been used to compare the cellular and subcellular distribution of nerve growth factor (NGF) and epidermal growth factor (EGF) in mouse submandibular glands. Rabbit antisera raised against purified proteins were characterized by immunoblot methods and were used to stain sections of salivary glands embedded in plastic. For light microscopy, antibodies were visualized by indirect immunofluorescence. For electron microscopy, thin sections were treated simultaneously with IgG against NGF and EGF coupled to colloidal gold particles of different size. Data indicate that NGF and EGF are present in all granular convoluted tubule cells and in no other cell type within the salivary gland. Ultrastructural analyses indicate that NGF and EGF are evenly distributed together within mature secretory granules, although a population of small granules was identified that is not immunoreactive for either protein. Taken together, the data suggest that granular convoluted tubule cells are homogeneous in the production and storage of NGF and EGF.

Animals↗
PubMed1987

Coordinated three-dimensional reconstruction from serial sections at macroscopic and microscopic levels of resolution: the human heart.

This report describes procedures we have developed for obtaining correlated quantitative structural information at two very different levels of resolution. Accurate reconstructions of entire organs and samples of tissue within organs were produced in correct scalar and topographical relationship using computer-assisted techniques. A specially designed sectioning apparatus, a macrovibratome, was used to section serially the ventricles of the human heart macroscopically. Photographs were taken of every slice. A tissue block excised from a slice at a specified locus in the left ventricular wall was embedded in plastic; serial-3 micron sections were cut in each of two orthogonal orientations. Photomicrographs were taken by semi-automated microscopy. Images of both macroscopic and microscopic sections were projected onto a bitpad and manually digitized. The resulting tables of x-, y-, and z-coordinates were reassembled on a VAX 11/750 computer, then transferred to a high-performance graphics workstation and displayed as three-dimensional images. Microscopic images were shown in the correct reference frame with respect to the macroscopic (parent) structure.

Heart↗
PubMed1989

Alteration of early vascular development after ablation of cranial neural crest.

A previous study has shown that, subsequent to ablation of cranial neural crest, heart morphology and pharyngeal arch vessels (aortic arches) are altered before septation of the outflow tract normally occurs. In the present study, we concentrated on very early development of the aortic arch apparatus in the chick (incubation days 3-5). The three-dimensional organization of the arch vessel apparatus was studied by scanning electron microscopy after intravascular injection of Mercox, and by serial sections of embryos embedded in plastic. Alterations in the arch vessel apparatus were already present by day three in embryos with neural crest ablation at stage 9-10. Bilateral symmetry frequently was lost. Arch vessels sometimes were enlarged and occupied most of the arch, with little surrounding mesenchyme. Some arch vessels were small or occluded. Mesenchyme was significantly reduced in quantity in the arches, and was not condensed and symmetrical as in controls. There was a significant increase in the proportion of direct apposition of vessel endothelium with epithelium, without the intervening mesenchyme typical of controls. The surgical manipulation used in this study leads to distinct alterations in the arches of components and relationships which are important in development. Altered blood flow likely affects the development of the heart.

Animals↗