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PubMedDate not supplied

[A synthetic review on the cerebral extracellular space evaluated by biochemical procedures (author's transl)].

The Authors present a synthetic review on the problem of the cerebral extracellular space evaluated by biochemical procedures. The studies in vitro are numerous, focused on various aspects, such as the choice of the marker, the influence of temperature, and that of the chemical composition of incubation media, the regional heterogeneity of the brain, and so on; it has been observed that inulin, which is the most commonly employed marker, gives an extracellular space of about 40-66%, whereas other markers give values higher than 45%; the variability of values depends on various experimental factors. The studies in vivo present some methodological difficulties due to the existence of the brain barrier; the most reliable procedure appears that of the continuous perfusion of the marker into the cerebrospinal fluid associated with a simultaneous intravenous perfusion; this procedure gives quantitative estimates of extracellular space of about 14-30%. Taking into account that other experimental methods (such as the morphological and the electrophysiological) give lower values, respectively of 5-20% and 18-25%, the Authors found that it should be possible to agree about an average value of cerebral extracellular space of 15-20%. This appears to be of some relevance especially in studying the pathological problems of the brain, and particularly cerebral edema.

Brain↗

PubMed1994

Intracellular and extracellular spaces and the direct quantification of molar intracellular concentrations of phosphorus metabolites in the isolated rat heart using 31P NMR spectroscopy and phosphonate markers.

To quantify metabolite and cation concentrations using NMR spectroscopy, the volumes of intracellular and extracellular spaces must be known. We describe a simple 31P NMR spectroscopic method that employs dimethyl methylphosphonate (DMMP) as a marker of total water space and phenylphosphonate (PPA) as a marker of extracellular space to determine intracellular and extracellular space volumes in the isolated, perfused rat heart. In vivo and in vitro radiolabel studies were used to verify this method. The difference between the total and extracellular water spaces, determined as milliliters/heart, gave the intracellular volume and allowed direct calculation of myocardial creatine phosphate, ATP, and inorganic phosphate concentrations, which were 13.4 mM, 10.1 mM, and 3.4 mM, respectively, for the glucose-perfused rat heart. The extracellular volume decreased by 84% in hearts subjected to 28 min total, global ischemia and increased by 15% during reperfusion. The method described allows the determination of intracellular energy metabolite concentrations in perfused rat heart directly from a single, fully relaxed 31P NMR spectrum.

Animals↗

PubMed1986

Ionic changes and alterations in the size of the extracellular space during epileptic activity.

Experiments with ion-selective microelectrodes revealed that a considerable activity of K ions appears temporarily in the extracellular space (ES) during enhanced neuronal activity and is removed from the ES by diffusion, active uptake, and entry into glial cells. The glial uptake results from the preferential glial K permeability and spatial glial K buffering. The glia responds to the local extracellular accumulation by a depolarization of the exposed part of its membrane. This depolarization will spread along the glial syncytium or extended glial cells. At sites where the extracellular K concentration has not yet increased, the membrane potential will thus be depolarized with respect to the K diffusion potential. Here K will move from the intra- into the extracellular space, in order to restore the electrochemical equilibrium. This induces a current that carries K into glial cells at sites of maximal K accumulation and that transports K out of glial cells at remote areas. In this way K is spatially redistributed. The corresponding current loop in the ES is predominantly carried by Na and Cl, the majority ions. Thus, Na and Ca are transported to the site of K accumulation while Cl moves away. The Cl and K ions are only partially replaced by Na. Hence, a decrease of extracellular osmolarity results, which leads to a water flux from the ES into the cells, inducing a shrinkage of the ES at sites of maximal K accumulation. At remote sites, the opposite effect is expected due to K flow out of glia and Cl transport to these sites. Thus, remote from the area of maximal neuronal activity, an increase of the ES is expected. This mechanism can explain the measured depth profile of the changes in the ES. At sites of maximal neuronal activity, the extracellular space undergoes a reduction by more than 30%. The ionic changes are accompanied by slow negative potential shifts. An increase in intracellular osmolarity due to enhanced metabolic activity and possibly KCl uptake mechanisms contributes to the changes in volume and ionic concentration. Model calculations of the after-effects of the loss of positive charges from the extracellular space and the K-specific glial buffering could predict size and time course of these changes. Experimental tests of this view include observations during epileptiform activity in gliotic scar foci as well as in hippocampal slices with depressed synaptic transmission. The extra- and intracellular ionic changes influence the generation, spread, and termination of seizure activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1982

Continuity of intracellular channels with extracellular space in adipose tissue and liver: demonstrated with tannic acid and lanthanum.

Tannic acid was used to demonstrate continuity of intracellular channels with extracellular space in white adipose tissue of adult rats, brown adipose tissue of suckling rats, and liver of diabetic rats. Electron-opaque material resulting from treatment of glutaraldehyde-fixed tissue with tannic acid was found in extracellular space, invaginations of cell surfaces, vesicles, and intracellular channels. Electron-opaque material was present in channels that surrounded lipid droplets in both white and brown adipocytes and in hepatocytes. The small distance between the lumen of marked channels and lipid droplets in adipocytes indicates that a monolayered structure, perhaps a leaflet of membrane lining the channel. Similar findings were obtained in brown adipose tissue using lanthanum instead of tannic acid to mark intracellular channels continuous with extracellular space. Since endoplasmic reticulum is the primary site of triacylglycerol synthesis in adipocytes, marked channels near lipid droplets may be elements of endoplasmic reticulum. Some of the channels marked with tannic acid in hepatocytes contained lipoprotein particles, whereas others were located, in relation to mitochondria and lipid droplets, in the same sites as endoplasmic reticulum in untreated tissue. This indicates that some of the channels marked with tannic acid in hepatocytes are endoplasmic reticulum. Presence of electron-opaque material in intracellular channels and vesicles, but not in cytoplasm, of treated tissue indicates the channels and vesicles were open to extracellular space during treatment with tannic acid or lanthanum and, furthermore, that their membranes were continuous with plasma membrane.

Adipose Tissue↗

PubMed2005

Nanostructure of the epidermal extracellular space as observed by cryo-electron microscopy of vitreous sections of human skin.

The newly developed method, cryo-electron microscopy of vitreous sections, was used to observe the nanostructure of the epidermal extracellular space. The data were obtained from vitreous sections of freshly taken, fully hydrated, non-cryo-protected human skin. The extracellular space of viable epidermis contains desmosomes, expressing a characteristic extracellular transverse approximately 5 nm periodicity, interconnected by a relatively electron lucent inter-desmosomal space. The extracellular space between viable and cornified epidermis contains transition desmosomes at different stages of reorganization interconnected by widened areas expressing a rich variety of complex membrane-like structures. The extracellular space of cornified epidermis contains approximately 9, approximately 14, approximately 25, approximately 33, approximately 39, approximately 44, and approximately 48 nm thick regions in turn containing one, two, four, six, eight, eight, and ten parallel electron-dense lines, respectively, between adjacent corneocyte lipid envelopes. The eight-line approximately 44 nm thick regions are most prevalent.

Adult↗

PubMed2002

Transient hypoxia-ischemia in rats: changes in diffusion-sensitive MR imaging findings, extracellular space, and Na+-K+ -adenosine triphosphatase and cytochrome oxidase activity.

PURPOSE: To investigate the correlation between diffusion-weighted (DW) magnetic resonance (MR) image changes with alterations in extracellular volume and changes in cytochrome oxidase and Na(+)-K(+)-adenosine triphosphatase (ATPase) activity at various times during and after cerebral hypoxia-ischemia in neonatal and juvenile rats. MATERIALS AND METHODS: One- and 4-week-old rats were randomly assigned to control or transient cerebral hypoxia-ischemia (ie, right carotid artery occlusion plus exposure to 8% oxygen) groups. Hypoxic-ischemic changes compared with normal ipsilateral brain tissue on DW images and the apparent diffusion coefficient of water were measured during and at 1 and 24 hours after hypoxia-ischemia ended. Hypoxic-ischemic changes in extracellular space and ipsilateral versus contralateral differences in Na(+)-K(+)-ATPase and cytochrome oxidase activity were measured. RESULTS: Hyperintensities on DW images obtained during hypoxia-ischemia correlated well (P <.05) with extracellular space reductions, which occurred 15 minutes earlier in the brains of 4-week-old rats than in the brains of 1-week-old rats. Similarly, within 1 hour after hypoxia-ischemia ended, DW image and extracellular space changes normalized. In contrast, Na(+)-K(+)-ATPase and cytochrome oxidase activity decreased in some regions during hypoxia-ischemia and remained reduced 1 hour after the end of hypoxia-ischemia. Twenty-four hours after signal intensity normalization, hyperintense areas reappeared on DW images, and Na(+)-K(+)-ATPase and cytochrome oxidase activity remained decreased. CONCLUSION: Signal intensity alterations with diffusion-sensitive MR imaging during and after transient hypoxia-ischemia are closely associated with a corresponding shrinkage and reexpansion of the extracellular space, irrespective of age. Mechanisms other than Na(+)-K(+)-ATPase changes may induce the early cell volume changes detected with diffusion-sensitive MR imaging.

Animals↗

PubMed1967

The extracellular space of voluntary muscle tissues.

The volume occupied by the extracellular space has been investigated in six types of voluntary muscles: sartorius (frog), semitendinosus (frog), tibialis anticus longus (frog), iliofibularis (frog), rectus abdominis (frog), and diaphragm (rat). With the aid of four types of probe material, three of which are conventionally employed (inulin, sorbitol, sucrose) and one of which is newly introduced (poly-L-glutamate), and a different experimental method, we have demonstrated that the "true" extracellular space of frog sartorius, semitendinosus, tibialis anticus longus, and iliofibularis muscle and of rat diaphragm muscle is equal to, or probably less than, 8-9% (v/w) of the tissue. The frog rectus muscle shows a somewhat higher ceiling value of 14%.

Animals↗

PubMed2006

Lysyl hydroxylase 3 (LH3) modifies proteins in the extracellular space, a novel mechanism for matrix remodeling.

Lysyl hydroxylase 3 (LH3), the multifunctional enzyme associated with collagen biosynthesis that possesses lysyl hydroxylase and collagen glycosyltransferase activities, has been characterized in the extracellular space in this study. Lysine modifications are known to occur in the endoplasmic reticulum (ER) prior to collagen triple-helix formation, but in this study we show that LH3 is also present and active in the extracellular space. Studies with in vitro cultured cells indicate that LH3, in addition to being an ER resident, is secreted from the cells and is found both in the medium and on the cell surface associated with collagens or other proteins with collagenous sequences. Furthermore, in vivo, LH3 is present in serum. LH3 protein levels correlate with the galactosylhydroxylysine glucosyltransferase (GGT) activity of mouse tissues. This, together with other data, indicates that LH3 is responsible for GGT activity in the tissues and that GGT activity assays can be used to quantify LH3 in tissues. LH3 in vivo is located in two compartments, in the ER and in the extracellular space, and the partitioning varies with tissue type. In mouse kidney the enzyme is located mainly intracellularly, whereas in mouse liver it is located solely in the extracellular space. The extracellular localization and the ability of LH3 to modify lysyl residues of extracellular proteins in their native, nondenaturated conformation reveals a new dynamic in extracellular matrix remodeling, suggesting a novel mechanism for adjusting the amount of hydroxylysine and hydroxylysine-linked carbohydrates in collagenous proteins.

Animals↗

PubMed1979

Potassium activity in photoreceptors, glial cells and extracellular space in the drone retina: changes during photostimulation.

1. A double-barrelled potassium-sensitive micro-electrode was developed that was fine enough to record intracellular electrical potentials and potassium activities (aK) in the drone retina. 2. aK was measured in the photoreceptor cells, in the pigment (glial) cells, and in the extracellular space, in the superfused, cut, retina. The effect of photostimulation was studied: 20 msec light flashes, intense enough to evoke receptor potentials of maximum amplitude were presented, 1/sec, in a train lasting about 2 min. 3. In photoreceptors with membrane potentials greater than or equal to 50 mV aK in the dark was 79 mM, S.D. = 27 mM, n = 11. During photostimulation aK fell by 21.5 +/- 9.5 mM with a half-time of 30 +/- 22 sec. (A tentative conversion from activities to free concentrations can be made by taking the activity coefficient as 0.70 its value in the Ringer solution). 4. In pigment cells with membrane potentials greater than or equal to 50 mV, aK in the dark was 52 mM, S.D. = 13 mM, n = 11. During photostimulation aK increased by 14 +/- 5 mM. 5. In the extracellular space aK increased during photostimulation with a mean half-time of less than 1.3 sec to a maximum (mean value 14 mM, S.D. = 8.4 mM, n = 22), and then fell to a plateau. 6. It is estimated from the anatomy that the photoreceptors occupy approximately 38% of the total volume of the retina, the pigment cells 57%, and extracellular space 5%. Hence, it seems possible that during photostimulation nearly all the net loss of potassium from the photoreceptors is temporarily stored in the pigment cells. 7. Recordings were made in the extracellular space of the intact animal by passing the electrode through a hole in the cornea. The mean aK in the dark was 7.7 mM, S.E. = 0.4 mM, n = 22. In the superfused retina, aK in the dark was 6.3 mM, S.E. = 0.7 mM, n = 22, even though aK in the Ringer solution was 2.2 mM. Increasing the aK of the Ringer solution to 7.0 mM had no apparent effect on aK in the extracellular space at depths greater than 20 micron. 8. In the intact animal the amplitude and time course of the change in extracellular aK evoked by the standard pattern of photostimulation were within the range observed in the superfused preparation.

Animals↗

PubMed1966

The extracellular space of the smooth muscle of the guinea-pig taenia coli.

1. The measured extracellular space of the taenia coli is large when small ions or molecules are used for the determination, and small when large molecules are used, even with identical experimental procedures.2. Extracellular hyaluronic acid has been detected histologically. It is apparently reduced by hyaluronidase.3. The extracellular inulin space increases after the tissue has been pretreated with hyaluronidase, although the ionic composition and wet weight are unchanged.4. It is suggested that the hyaluronic acid prevents the free entry of macromolecules such as inulin into the extracellular space by steric hindrance. Monatomic ions such as Na(+), Li(+), Cl(-), Ca(2+) therefore have a larger extracellular space available than is calculated on the basis of the inulin space.5. A slight shrinkage of the muscle cells can be detected when the incubation period is prolonged.

Animals↗

PubMed2003

Life-long calorie restriction in Fischer 344 rats attenuates age-related loss in skeletal muscle-specific force and reduces extracellular space.

The decline in muscle function is associated with an age-related decrease in muscle mass and an age-related decline in strength. However, decreased strength is not solely due to decreased muscle mass. The age-related decline in muscle-specific force (force/muscle cross-sectional area), a measure of intrinsic muscle function, also contributes to age-related strength decline, and the mechanisms by which this occurs are only partially known. Moreover, changes in the extracellular space could have a profound effect on skeletal muscle function. Life-long calorie restriction in rodents has shown to be a powerful anti-aging intervention. In this study, we examine whether calorie restriction is able to attenuate the loss of muscle function and elevations in extracellular space associated with aging. We hypothesize that calorie restriction attenuates the age-associated decline in specific force and increases in extracellular space. Measurements of in vitro contractile properties of the extensor digitorum longus (type II) and soleus (type I) muscles from 12-mo and 26- to 28-mo-old ad libitum-fed, as well as 27- to 28-mo-old life-long calorie-restricted male Fischer 344 rats, were performed. We found that calorie restriction attenuated the age-associated decline in muscle mass-to-body mass ratio (mg/g) and strength-to-body mass ratio (N/kg) in the extensor digitorum longus muscle (P < 0.05) but not in the soleus muscle (P > 0.05). Importantly, muscle-specific force (N/cm2) in the extensor digitorum longus, but not in the soleus muscle, of the old calorie-restricted rats was equal to that of the young 12-mo-old animals. Moreover, the age-associated increase in extracellular space was reduced in the fast-twitch extensor digitorum longus muscle (P < 0.05) but not in the soleus muscle with calorie restriction. We also found a significant correlation between the extracellular space and the muscle-specific force in the extensor digitorum longus (r = -0.58; P < 0.05) but not in the soleus muscle (r = -0.38; P > 0.05). Hence, this study shows a loss of muscle function with age and suggests that long-term calorie restriction is an effective intervention against the loss of muscle function with age.

Aging↗

PubMed1993

Extracellular space parameters in the rat neocortex and subcortical white matter during postnatal development determined by diffusion analysis.

Extracellular space volume fraction, tortuosity and nonspecific uptake of tetramethylammonium--three diffusion parameters of brain tissue--were measured in gray matter of the somatosensory neocortex and subcortical white matter of the rat during postnatal development. The three parameters were determined from concentration-time profiles of tetramethylammonium in postnatal days 2-120 in vivo. Tetramethylammonium concentration was measured with ion-selective microelectrodes positioned 130-200 microns from an iontophoretic source. Data were correlated with cytoarchitectonic structure and average thickness of the regions in 0-90-day-old rats using rapidly frozen tissue. Extracellular space volume fraction was largest in the newborn rats and diminished with age. In two-to three-day-old animals, volume fraction (mean +/- S.E.) was 0.36 +/- 0.04 in layers III and IV, 0.38 +/- 0.02 in layer V, 0.41 +/- 0.01 in layer VI and 0.46 +/- 0.01 in white matter. The earliest decrease in volume fraction was found in layers V and VI at postnatal days 6-7 followed by a decrease in layer III and IV at postnatal days 8-9 and in white matter at postnatal days 10-11. A further dramatic reduction in volume fraction occurred in all cortical layers and especially in the white matter between postnatal days 10 and 21. There was no further decrease in volume fraction between postnatal day 21 and adults (90-120 days old). The adult volume fraction values were: layer II, 0.19 +/- 0.002; III, 0.20 +/- 0.004; IV, 0.21 +/- 0.003; V, 0.22 +/- 0.003; VI, 0.23 +/- 0.007; white matter, 0.20 +/- 0.008. Values of tortuosity ranged between 1.51 and 1.65, nonspecific cellular uptake varied from 3.3 x 10(-3)/s to 6.3 x 10(-3)/s. The variations in each parameter were not statistically significant at any age. These data represent the first characterization of diffusion parameters in a developing brain. They confirm previous histological indications of a relatively large extracellular volume fraction during early postnatal development. The constancy of the tortuosity shows that diffusion of small molecules is no more hindered in the developing brain than in the adult. The large extracellular space volume fraction of the neonatal brain could significantly dilute ions, metabolites and neuroactive substances released from cells, relative to release in adults, and may be a factor in preventing anoxia, seizure and spreading depression in young animals. The diffusion characteristics could also play an important role in the developmental process itself.

Aging↗

PubMed1982

The permeability of the extracellular spaces at the Schmidt-Lanterman clefts and paranodes in peripheral myelin sheaths.

Electron dense material was observed in the extracellular spaces between adjacent components of the Schmidt-Lanterman clefts and between lateral loops at the paranodes in some of the heavily myelinated fibers of the anterior roots and peripheral nerves of a patient with amyotrophic lateral sclerosis. Similar deposits were seen in tissue derived from patients who died with no neurological disease. These deposits were also present in the extracellular spaces of the endoneurium and beneath the outer cytoplasmic collar of the sheath, but did not penetrate the intraperiod line of the compact myelin or the periaxonal space and the lateral loops tended to remain in contact with the axon. The findings suggest that a pathway exists between the extracellular spaces outside the sheath to the innermost portion of the sheath but that the periaxonal space is resistant to the penetration of the extraneous material.

Aged↗

PubMed1991

Elevated extracellular potassium is associated with a reduced extracellular space in rat neural lobe in vitro.

Increased neural activity of neurosecretory cells is accompanied by large increases in extracellular K+. The possibility that elevations of this ion might involve fluid redistribution and thus affect the size of the extracellular space and the relationship between pituicytes and axons in the rat neural lobe was explored using rapid freezing and freeze-substitution. Neural lobes were incubated for 15 min before freezing either in a normal medium or one containing a 10 mM increase in KCl (high KCl), a 10 mM increase in KCl balanced by an equimolar reduction in NaCl (high KCl-low NaCl), or only a 10 mM reduction in NaCl (low NaCl). A quantitative assessment of the region of good fixation was made to determine the relative fractions occupied by axons, pituicytes and the extracellular space near the neurohaemal contact zone. In addition, the percentage of basal lamina contacted by pituicytes and axons was calculated, as was the degree of enclosure of axons by pituicytes. In neural lobes incubated in normal medium, the extracellular space accounted for approximately 30% of the cross-sectional area of the neuropil and could be divided into two domains: an extended perivascular space (28-29% of total area); and a narrow (approximately 24 nm; approximately 1% of total) space between closely apposed neurosecretory processes or between these processes and pituicytes. Pituicytes occupied almost 60% of the basal lamina at the neurohaemal contact zone, while axons occupied approximately 20%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2003

Evidence for chelatable zinc in the extracellular space of the hippocampus, but little evidence for synaptic release of Zn.

Zinc colocalizes with glutamate in the synaptic vesicles of certain glutamatergic vesicles in the mammalian brain. Here, I introduce a method for detecting Zn in the extracellular space of brain slices and another method for detecting the passage of Zn out of the slice. In both cases, the fluorimetric Zn probe FluoZin-3 is used in conjunction with a slow Zn chelator, Ca-EDTA, to reduce background fluorescence. In addition, a new Zn chelator, ethylenediiminodi-2-pentanedioic acid, with little affinity for Ca or Mg is introduced. These tools are then used to show that little Zn (approximately 2 nm) is released during the course of synaptic transmission into the extracellular space. However, when hippocampal slices are subjected to a high potassium stimulus (50 mM) combined with an increase in osmolarity, Zn is externalized in the Timm's-stained areas (approximately 6 nm). This stimulus also leads to even greater Zn elevations in area CA1 that is only weakly stained by the Timm's method. Nevertheless, even under these conditions, little if any Zn makes its way out of the slices. I present evidence for a layer of Zn in the extracellular space that maps onto the Timm's stained region of the hippocampus. This Zn veneer appears to be loosely associated with molecules in the extracellular space and may be the raison d'être for vesicular Zn.

Animals↗

PubMed2002

Relationship between zinc and neurotransmitters released into the amygdalar extracellular space.

On the basis of the evidence that vesicular zinc may be essential to the functions of the amygdala, the movement and action of actively functioning zinc in synapses in the amygdala of rats were studied using in vivo microdialysis. The increase of (65)Zn release into the amygdalar extracellular space during stimulation with high K(+) was inhibited by the addition of 1 microM tetrodotoxin. High-K(+)-induced (65)Zn release was not observed in the substantia nigra, in which zinc-containing glutamatergic neuron terminals are assumed not to exist. The amount of (65)Zn released into the amygdalar extracellular space during stimulation with high K(+) was correlated with that of glutamate. These results suggest that zinc may be concurrently released with glutamate from the neuron terminals in the amygdala and that zinc may cooperate with glutamate in excitatory neurotransmission. When the amygdala was perfused with 10 microM calcium-ethylenediamine tetraacetic acid (CaEDTA) to chelate zinc in the extracellular space, the levels of glutamate in the extracellular space were not appreciably influenced, whereas those of gamma-aminobutyric acid (GABA) were remarkably increased. It is likely that vesicular zinc modulates GABA release in the amygdala. The modulation of GABAergic neuron activity by zinc may be important for the functions of the amygdala.

Amygdala↗

PubMed1992

Quantitative analysis of extracellular space using the method of TMA+ iontophoresis and the issue of TMA+ uptake.

The tetramethylammonium (TMA+) method for measuring the volume fraction and tortuosity of brain extracellular space is presented in detail. The temporal and spatial distribution of TMA+ in the extracellular space following iontophoresis or pressure microinjection is described by suitable equations and illustrated with graphs. By fitting the equations to the concentration versus time data obtained from measurements with ion-selective micropipettes, the volume fraction and tortuosity can be measured. In addition, the concentration-dependent uptake of TMA+ can be estimated from the given equations. The final section of the paper derives simple numerical estimates of TMA+ loss from the extracellular space by this mechanism.

Animals↗

PubMed1980

Preservation of extracellular space during fixation of the brain for electron microscopy.

Adult mammalian brain contains about 20% extracellular space, but fixatives cause the cellular processes to ingest the extracellular fluid, and the space is not preserved in electron micrographs prepared by any of the conventional methods. This distortion can be prevented by replacing part of the sodium chloride in the extracellular fluid by an impermeant solute such as sucrose. To do this, the blood-brain barrier can be opened by vascular perfusion at 300 mmHg pressure, or the barrier can be bypassed by immersion of thin slices of fresh brain in the impermeant solution. In either case, addition of aldehyde fixatives and conventional processing then leads to the preservation of extracellular space in electron micrographs. Both procedures are as easy to use for routine fixation as conventional methods. In well fixed tissue the cellular processes are different in size, shape and electron density from the inflated profiles seen after the ingestion of extracellular fluid that accompanies conventional fixation. Moreover, extracellular space is found to separate widely some cellular elements, while leaving others contiguous.

Animals↗