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At least 19 recordsLinked to original sources

PubMed1999

Mitochondrial cristae diversity in human Leydig cells: a revised look at cristae morphology in these steroid-producing cells.

Mitochondria of steroid-producing cells are integrally involved with steroidogenesis. For decades, the mitochondrial morphology of Leydig cells, as with other steroid-producing cells, has been known to differ from typical mitochondria in that the cristae are predominately "tubular." In a few species, humans being one example, the cristae have often been further categorized as "tubular and/or lamellar," without further elaboration. In the present study, mitochondria of human Leydig cells were examined with the purpose of providing a more detailed description of "cristae" morphology in these steroid-producing cells. The cristae are found to be rather diverse in morphology, consisting of elements of anastomosing tubules in continuity with small cisternal regions as well as with stacked arrays of lamellae, referred to as "lamellar associations." The tubular elements are found to branch in a tripartite fashion and sometimes to expand into small cisternal elements at these junctures. The lamellar associations are a distinctive feature of cristae in human Leydig cells and consist of two to eight closely apposed lamellae with a consistent gap of approximately 4 nm between the membranes of apposing lamellae. Such a close association of cellular membranes is highly suggestive of an integral transmembrane linkage. Although the lamellar associations often appear isolated, evidence is present of a continuity of this compartment of the cristae with the tubular elements. The connections (termed "initial segments") of the various forms of the cristae to the inner mitochondrial membrane are typically via tubules. Mitochondria exhibiting a central region of matrix delineated by one or more cup-shaped lamellae are also present. The pleomorphic structure of mitochondrial cristae in human Leydig cells reemphasizes our present lack of knowledge of how subcellular structure relates to steroidogenesis.

Adolescent↗

PubMed1979

Horizontal ampullary nerve fiber projections to the crista angustarum in the crista ampullaris.

Individual nerve fibers were traced on consecutive serial 1-micron-thick cross-sections to determine their position of origin within the horizontal ampullary nerve trunk (HANT) and the site at which they penetrated the basilar lamina of the horizontal crista in the guitarfish, Rhinobatos productus. Of the 132 fibers successfully traced, 87.1% followed an anatomical projection pattern consistent with the dynamic response characteristics of the nerve fibers. That projection pattern was: from the peripheral HANT region to the ipsilateral slope; from the central HANT region to the crest; and from the intermediate HANT region both to the ipsilateral slope and the crest of the horizontal crista. The 12.9% of "error" fibers not following this projection pattern were also consistent with the functional neurophysiological data. The terms crista bulbus and crista angustarum were introduced to designate specific anatomical regions of the dumb-bell shaped crista ampullaris.

Animals↗

PubMed2002

Lamellar and tubular associations of the mitochondrial cristae: unique forms of the cristae present in steroid-producing cells.

This report provides a survey of mitochondrial structure in numerous cell types from all basic tissue types (epithelial, connective, muscular and nervous) with the main purpose being to determine the presence or absence of a form of the cristae previously termed the lamellar association (LA) (Anat. Rec. , 254 (1999) 534). The LA is a complex of closely apposed lamellar cristae within the inner membrane system of the mitochondria of Leydig cells, the steroid-producing cells of the testis. These lamellae are separated by a gap of approximately 4 nm. This survey has found no evidence of the LA in non-steroid-producing cells. The LA is a common cristae morphology in human Leydig cells, but is rare in marmoset Leydig cells, where instead, tubular associations (TA) are found. Cells of other steroid-producing cells are not included in this survey. Published micrographs from the literature do, however, have evidence of the existence of the LA and TA in other steroid-producing cells. It is concluded that these membrane substructures of the inner mitochondrial membrane are unique to steroid-producing cells. It is suggested that the LA is a region of the cristae, which is not involved with adenosine triphosphate (ATP) production, since the dimensions do not allow for F1 complexes on the matrix side of the cristae. The significance of this remains elusive.

Journal Article↗

PubMed1993

[The basic types and forms of the fine structure of mitochondrial cristae: the degree of their evolutionary stability (capacity for morphological transformations)].

The organellological analysis being made of the fine structure of mitochondria in different species of the kingdom Protista, and in different cells of representatives of the kingdoms Plantae and Animalia (Metazoa). On the base of this analysis the following classification of types and forms of the fine structure of mitochondrial cristae is proposed. The Ist type, with lamellar (flat) cristae includes four morphological forms: ribbon, sheet, bundle-like and rounded ones (discoidal and plate-like). The 2nd type, with vesicular cristae, includes bubble, ampule, and sac-like ones. The 3rd type with tubular cristae. Among the representatives of each kingdom (Protista, Plantae and Metazoa) all the three types of mitochondrial cristae have been observed. The majority of cells of higher plants and higher animals have lamellar mitochondrial cristae, but sometimes (in some tissues) there are cells with tubular or vesicular mitochondrial cristae. On the base of the above classification some other conclusions have been made. Among the eukaryotes the vesicular cristae are spread as widely as tubular and lamellar ones. Only in a few macrotaxa (superphyla and phyla) of Protista all the investigated organisms have mitochondria of similar cristal organization. For example, Ciliophora have only tubular, and Cryptophyta only lamellar mitochondrial cristae. In the majority of protistan macrotaxa a certain mitochondrial type of cristae may dominate, but there is the number of species with some different mitochondrial patterns (Euglenophyta, Chlorophyta, Chrysophyta, Mycetozoa, etc.). In some macrotaxa (Chrysophyta, Mycetozoa, etc.) such mitochondrial patterns as mentioned above, are characteristic of the lower organisms. Finally, in some macrotaxa of Protista mitochondrial cristae of two or three types may appear in different species, sometimes even within the same genus; for example--Sporozoa, Myxospora and Ascetospora. In the course of ontogenesis of the vertebrates and insects, cell mitochondria in some of their tissues can change their morphological type from lamellar to tubular or vesicular. Similar transformations of mitochondrial cristae were observed in the life cycles of some trypanosomes (Kinetoplastida) and in the flagellate Polytoma (Chlorophyta) due to modifications in the culture conditions. It is undoubtedly that the principle of morphological concervatism in the organization of mitochondrial cristae may be used for purposes of systematics and phylogeny, however only after a thorough comparative organellological analysis of the fine structure in numerous species of the examined taxon.

Animals↗

PubMed1998

Conduction properties of the crista terminalis in patients with typical atrial flutter: basis for a line of block in the reentrant circuit.

INTRODUCTION: Previous mapping studies in patients with typical atrial flutter have demonstrated the crista terminalis to be a posterior barrier of the reentrant circuit forming a line of block. However, the functional role of the crista terminalis in patients with or without a history of atrial flutter is not well known. The aim of this study was to determine whether the conduction properties of the crista terminalis are different between patients with and those without a history of atrial flutter. METHODS AND RESULTS: The study population consisted of 12 patients with clinically documented atrial flutter (group 1) and 12 patients with paroxysmal supraventricular tachycardia as well as induced atrial flutter (group 2). A 7-French, 20-pole, deflectable Halo catheter was positioned around the tricuspid annulus. A 7-French, 20-pole Crista catheter was placed along the crista terminalis identified by the recording of double potentials with opposite activation sequences during typical atrial flutter. After sinus rhythm was restored, pacing from the low posterior right atrium near the crista terminalis was performed at multiple cycle length to 2:1 atrial capture. No double potentials were recorded along the crista terminalis during sinus rhythm in both groups. In group 1, the longest pacing cycle length that resulted in a line of block with double potentials along the crista terminalis was 638 +/- 119 msec. After infusion of propranolol, it was prolonged to 832 +/- 93 msec without change of the interdeflection intervals of double potentials. In group 2, the longest pacing cycle length that resulted in a line of block with double potentials along the crista terminalis was 214 +/- 23 msec. After infusion of procainamide, it was prolonged to 306 +/- 36 msec with increase of interdeflection interval of double potentials. CONCLUSION: The crista terminalis forms a line of transverse conduction block during typical atrial flutter. Poor transverse conduction property in the crista terminalis may be the requisite substrate for clinical occurrence of typical atrial flutter.

Adult↗

PubMed2003

Three-dimensional analysis of mouse rod and cone mitochondrial cristae architecture: bioenergetic and functional implications.

PURPOSE: Comparative studies of structure related to function offer a promising means of understanding the significance of differences in cytoarchitecture. Mitochondrial crista structure is linked tightly to mitochondrial function. Non-foveal cone photoreceptors of primates contain considerably more inner segment mitochondria and have higher oxidative enzyme activity than do rods. In addition, it is suggested that light-adapted cones have a higher aerobic ATP demand than light-adapted rods. Therefore, we investigated the oxidative metabolism and three-dimensional membrane architecture of mouse rod and cone inner segment mitochondria. METHODS: We determined the number, size, cytochrome c oxidase (CO) reactivity, and membrane architecture of rod and middle wavelength-sensitive (M) cone inner segment mitochondria from 21 day old light-adapted C57BL/6 mice using conventional electron microscopy and the three-dimensional approach of single- and double-tilt electron microscope tomography. Fourteen different measurements of mitochondrial substructures were analyzed. Photoreceptor oxygen consumption was determined in dark- and light-adapted retinas. RESULTS: Rod and cone mitochondria displayed an orthodox conformation. Cone inner segments, compared to rods, contained 2-fold more mitochondria and were more CO reactive. Rod and cone mitochondria had similar outer-inner membrane width, contact site width, diameter and density, crista width, number of cristae/volume, number of cristae segments/volume, and fraction of cristae with multiple segments. In contrast, cone mitochondria had narrower crista junctions, greater cristae connectivity, and approximately 3-fold more cristae membrane surface area compared to rods. The increased cristae membrane surface area in cones was accomplished by connecting more cristae segments together, rather than by creating more cristae. CONCLUSIONS: These results demonstrate that middle wavelength (M) cones have a different bioenergetic signature than do rods and suggest that the aerobic ATP demand and production is greater in light-adapted cones than in light-adapted rods. Cones utilize two complimentary strategies to increase their aerobic ATP production: increase the number of mitochondria and increase the cristae surface membrane area. The greater ATP generation by cones may also provide increased protection against metabolic insults and apoptosis compared to rods.

Adenosine Triphosphate↗

PubMed1998

Electron tomography of mitochondria from brown adipocytes reveals crista junctions.

Electron microscope tomography was used to examine the membrane topology of brown adipose tissue (BAT) mitochondria prepared by cryofixation or chemical fixation techniques. These mitochondria contain an uncoupling protein which results in the conversion of energy from electron transport into heat. The three-dimensional reconstructions of BAT mitochondria provided a view of the inner mitochondrial membrane different in important features from descriptions found in the literature. The work reported here provides new insight into BAT mitochondria architecture by identifying crista junctions, including multiple junctions connecting a crista to the same side of the inner boundary membrane, in a class of mitochondria that have no tubular cristae, but only lamellar cristae. Crista junctions were defined previously as the tubular membranes of relatively uniform diameter that connect a crista membrane with the inner boundary membrane. We have also found that the cristae architecture of cryofixed mitochondria, including crista junctions, is similar to that found in chemically fixed mitochondria, suggesting that this architecture is not a fixation artifact. The stacks of lamellar cristae extended through more of the BAT mitochondrial volume than did the cristae we observed in neuronal mitochondria. Hence, the inner membrane surface area was larger in the former. In chemically fixed mitochondria, contact sites were easily visualized because the outer and inner boundary membranes were separated by an 8 nm space. However, in cryofixed mitochondria almost all the outer membrane was observed to be in close contact with the inner boundary membrane.

Adipocytes↗

PubMed2004

Electrophysiological mechanisms and catheter ablation of complex atrial arrhythmias from crista terminalis:.

Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 +/- 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9 +/- 5 months (range 5-18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.

Aged↗

PubMed1988

A long-range ordered structure in mitochondrial cristae revealed by a pathological structural modification.

An experimentally imposed 6-hr local ischemia in the anterior wall of the left ventricle in dog hearts leads to a structural modification of the mitochondria in the posterior wall with the cristae revealing a zig-zag pattern when viewed in cross sections. This pattern was found to reveal a change in the distribution of crista mass with an increase of mass at circumscribed regions in each crista membrane and a reduction of mass from the surrounding region in each crista membrane. The accumulation of mass contributed to the elevations that caused the zig-zag pattern. These elevations were distributed according to a tetragonal pattern with a periodicity of 850 A. The tetragonal pattern contributed by one crista membrane was translocated halfway along the diagonals of the tetrameric pattern of the other crista membrane within each crista. The change in mass distribution reveals differences in the strength of bonds that account for binding of the proteins to the cristae with strong bonds in the elevated regions, while enzymes less firmly bound are located in the surrounding region. The respiratory chain enzymes will then be located in the elevated regions and the soluble enzymes including the tricarboxylic acid cycle enzymes will be located in the surrounding region. The tissue in the posterior wall was functionally impaired and normal function was restored when substrate for oxidative phosphorylation was added to the blood perfusing the tissue. It is concluded that the functional impairment is a consequence of a partial breakdown of the structural organization of the tricarboxylic acid cycle enzymes. The discovery of a long-range structural order involving the entire cristae reveals that the enzymes of the multienzyme systems as well as those systems in the cristae are structurally highly organized and it excludes that the enzymes are randomly mixed and highly mobile.

Animals↗

PubMed2000

Accuracy of fluoroscopic localization of the Crista terminalis documented by intracardiac echocardiography.

The crista terminalis is an important anatomic target for ablation of atrial arrhythmias. We determined the accuracy of catheter placement guided by fluoroscopy alone when directed to 24 sites along the crista terminalis in 6 patients. The sites selected included the most medial superior, most lateral superior, mid lateral, and most inferolateral sites along the crista terminalis in each patient. These sites were selected because of their recognized importance in sinus node and/or atrial tachycardia ablation and the importance of avoiding caval structures when targeting the most superior and/or inferior right atrium. The position of the catheter tip was documented using a catheter based ultrasound transducer in the right atrium or vena cava. The operator was blinded to the intracardiac echocardiographic (ICE) results until reviewing the images after the procedure in each patient. The catheter tip, guided by fluoroscopy alone, was identified by ICE to be within the right atrium and within 1cm of the crista terminalis at only 10 of the 24 sites (42%). Importantly, when targeting the most superior and inferior sites along the crista terminalis, the catheter tip, guided by fluoroscopy, was noted to be adjacent to the venous junction with the right atrium but actually located in the superior or inferior vena cava at 5 of the 18 such sites. The catheter was positioned appropriately (within 1 cm of the crista and within the right atrium) guided by fluoroscopy alone when targeting 1 of the 12 sites in the first 3 patients versus 9 of 12 sites in the last 3 patients, p<0.05. In conclusion, it appears that using fluoroscopic guidance alone: 1) localization of the crista terminalis is frequently inaccurate and 2) catheter positioning in the superior/inferior vena cava is commonly noted when targeting very superior and inferior sites along the crista terminalis. A learning curve, assisted by review of ICE recordings after each procedure, appears to improve the accuracy of catheter placement by fluoroscopy alone but still does not result in uniform success. ICE appears to facilitate and ensure accurate targeting of specific anatomic sites along the crista terminalis and thus may serve as an important adjunctive imaging technique in electrophysiology.

Adult↗

PubMed1995

Hair-cell counts and afferent innervation patterns in the cristae ampullares of the squirrel monkey with a comparison to the chinchilla.

1. The numbers of type I and type II hair cells were estimated by dissector techniques applied to semithin, stained sections of the horizontal, superior, and posterior cristae in the squirrel monkey and the chinchilla. 2. The crista in each species was divided into concentrically arranged central, intermediate, and peripheral zones of equal areas. The three zones can be distinguished by the sizes of individual hair cells and calyx endings, by the density of hair cells, and by the relative frequency of calyx endings innervating single or multiple type I hair cells. 3. In the monkey crista, type I hair cells outnumber type II hair cells by a ratio of almost 3:1. The ratio decreases from 4-5:1 in the central and intermediate zones to under 2:1 in the peripheral zone. For the chinchilla, the ratio is near 1:1 for the entire crista and decreases only slightly between the central and peripheral zones. 4. Nerve fibers supplying the cristae in the squirrel monkey were labeled by extracellular injections of horseradish peroxidase (HRP) into the vestibular nerve. Peripheral terminations of individual fibers were reconstructed and related to the zones of the cristae they innervated and to the sizes of their parent axons. Results were similar for the horizontal, superior, and posterior cristae. 5. Axons seldom bifurcate below the neuroepithelium. Most fibers begin branching shortly after crossing the basement membrane. Their terminal arbors are compact, usually extending no more than 50-100 microns from the parent exon. A small number of long intraepithelial fibers enter the intermediate and peripheral zones of the cristae near its base, then run unbranched for long distances through the neuroepithelium to reach the central zone. 6. There are three classes of afferent fibers innervating the monkey crista. Calyx fibers terminate exclusively on type I hair cells, and bouton fibers end only on type II hair cells. Dimorphic fibers provide a mixed innervation, including calyx endings to type I hair cells and bouton endings to type II hair cells. Long intraepithelial fibers are calyx and dimorphic units, whose terminal fields are similar to those of other fibers. The central zone is innervated by calyx and dimorphic fibers; the peripheral zone, by bouton and dimorphic fibers; and the intermediate zone, by all three kinds of fibers. Internal (axon) diameters are largest for calyx fibers and smallest for bouton fibers. Of the entire sample of 286 labeled fibers, 52% were dimorphic units, 40% were calyx units, and 8% were bouton units.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1975

Semimicroscopical observations on the crista stapedis.

Adult and fetal human stapes were removed by means of the stereoscopic microscope in order to compare the size of the lamina or crista that joins the crura of the stapes and rests in the lateral aspect of the basis. 65 out of 110 specimens showed cristae of different sizes, whereas the remaining 35% did not possess this structure. The cristae were classified into large, medium-sized and rudimentary. Several incomplete or irregular structures were also found. The cristae or laminae divide the lateral aspect of the base into two fossae: a small upper one and a large lower one, although several variations were found. An edge of the pillar groove was usually continuous with the cristae; however, compact pillars were found at the point where they reach the base, where the cristae orginates. Asymmetrical cristae and changes in the general shape of the stapes were found in several specimens. Two ossicles showed crista with orifices due to resorption or to the passage of vessels.

Adult↗

PubMedDate not supplied

Crista neglecta in man.

The prevalence, location, and size of the crista neglecta in man were investigated by examining the histological sections of 223 human temporal bones (137 cases). The relationship between the crista neglecta and the singular nerve was also described. The crista neglecta was observed in 17 cases, ranging in age from 15-week fetal life to 76 years. This structure was located on the wall of the anterolateral quadrant of the posterior canal ampulla, close to the cribriform area of the singular nerve in the area between the utriculoampullar duct and the intermediate portion of the posterior canal crista. The average width, length, and height of the crista neglecta were described. The crista neglecta had a mound-like shape and contained nerve fibers, transitional epithelium, sensory hair cells, and a cupula. The nerve fibers from the crista neglecta were joined to a small branch of the singular nerve at the cribriform area in 5 of 17 crista neglecta cases, and to the main trunk of the singular nerve in the remaining 12 cases.

Aged↗

PubMed2001

Anatomic and morphometric changes to gerbil posterior cristas following transtympanic administration of gentamicin and streptomycin.

Many studies have sought to document ototoxic damage and to study repair and regeneration of mammalian vestibular sensory epithelia. However, linear density analysis of the sensory cells or use of methods that focus on detection of actin in the stereocilia and cuticular plates at the reticular lamina detect only the disappearance of "hair cells" as defined by a narrow set of criteria. The research presented here focuses on the effects of two ototoxic drugs (gentamicin and streptomycin). We used light microscopic analysis of semithin sections to observe changes in the distribution of sensory and supporting cell nuclei and to elucidate other, previously undetected, morphological changes that occurred within the vestibular epithelia. Age-matched untreated and vehicle-treated controls showed that the gerbil posterior crista is asymmetrical on either side of the septum cruciatum; the longer end is taller and narrower than the shorter end. In cross sections taken throughout the length of each posterior crista, the thickness of the sensory epithelium along the sides (peripheral zone) is greater than at the apex (central zone). In tissue sections of the sensory epithelium, the ratio of sensory cell nuclei to support cell nuclei is slightly over 1:1.5 in all regions except the septum cruciatum where most sensory cells are absent and supporting cells predominate. In tissue sections from the most damaged drug-treated specimens, there was a decrease in the linear density of nuclei in the sensory cell layer, with a compensatory increase in the linear density of nuclei in the support cell layer of the sensory epithelia. In these specimens, linear density of total nuclei/tissue section remained the same. In these regions, the width of the epithelium became up to 50% thinner. The ratio of sensory to supporting cell nuclei changed to 1:6. Drug exposure led additionally to a decrease in length of the cristas, but there was not a linear relationship between the change in length of the crista and length of the septum cruciatum in these shorter cristas. In drug-treated cristas, other changes included a decrease in calculated surface area and volume of the epithelia. Thus, while linear density measurements of sensory cell nuclei provide an indication of damage, there are additional anatomic changes to the cristas and caution is advised with regard to interpreting changes as "loss" of cells.

Animals↗

PubMed1994

Hair cells of different shapes and their placement along the frog crista ampullaris.

The list of distinguishing morphological features of hair cells includes: Type I and Type II afferent innervation, and length, shapes and arrangements of stereo- and kinocilia. We now add to this list the shapes of the hair cells themselves and their placement within the mechanosensory organ, in this case the semicircular canal. Although hair cells of the crista ampullaris of the frog are only of Type II they may now be further classified into three sub-groups according to shape: club-, cigar- and pear-shaped. The cigar- and club-shaped hair cells are each about 40% while the pear-shaped cells are about 20% of the total numbers of hair cells in the crista. The differently-shaped hair cells also distribute differently along the crista. The cigar- and club-shaped are more-or-less uniformly distributed with somewhat higher concentrations at the ends of the crista than in the center. The pear-shaped hair cells, on the other hand, are mostly concentrated toward the center of the crista. This distribution of the pear-shaped hair cells, and their shape is reminiscent of the distribution of calyceal endings (Type I hair cell) in the cristae of amniotes [Goldberg et al., Hear. Res. 49, 89-102 (1990) in Chinchilla; Fernandez et al., Soc. Neurosci. Abstr. 17, 312 (1991) in Monkey]. There are some quantitative differences between hair cells of the same shape but from different portions of the crista. For instance, pear-shaped hair cells of the center are generally of greater cross-sectional area than those of the ends.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2004

Comparative morphology of rodent vestibular periphery. II. Cristae ampullares.

We made flattened neuroepithelial preparations of horizontal and vertical (anterior and posterior) cristae from mouse, rat, gerbil, guinea pig, chinchilla, and tree squirrel. Calretinin immunohistochemistry was used to label the calyx class of afferents. Because these afferents are restricted to the central zone of the crista, their distribution allowed us to delineate this zone. In addition to calyx afferents, calretinin also labels approximately 5% of type I hair cells and 20% of type II hair cells throughout the mouse and rat crista epithelium. Measurements of the dimensions of the cristae and counts of hair cells and calyx afferents were determined on all species. Numbers of calyx afferents, hair cells, area, length, and width of the sensory epithelium increase from mouse to tree squirrel. As in the companion paper, we obtained additional data on vestibular end organ dimensions from the literature to construct a power law function describing the relationship between crista surface area and body weight. The vertical cristae of the mouse, rat, and gerbil have an eminentia cruciatum, a region located transversely along the midpoint of the sensory organ and consisting of nonsensory cells. Apart from this eminentia cruciatum, there are no statistical differences between horizontal and vertical cristae with regard to area, width, length, the number and type of hair cells, and number of calretinin-labeled calyx afferents.

Afferent Pathways↗

PubMed2003

Differences in the crista dentata structure of the ischium of the third maxilliped in Astacus leptodactylus (Eschscholtz, 1823).

The differences in the crista dentata structure of the ischium of third maxilliped in different size Astacus leptodactylus (36-80 mm carapace length) were investigated. The results showed that four different types of crista dentata structure and teeth number occur in the third maxillipeds of A. leptodactylus. These are: (1) same number of teeth in the crista dentata of right and left third maxilliped, but not in the same structure, (2) different number and structure of teeth in the crista dentata of right and left third maxilliped, (3) same number and structure ofteeth in the crista dentata of right and left third maxilliped, (4) same sturucture of teeth in the crista dentata of right and left third maxilliped, but not same number of irregular teeth. In conclusion, it is believed that the differences in the crista dentata structure and different tooth number of the ischium of maxilliped cause a different cutting edge and variations in the food choice of A. leptodactylus.

Animals↗

PubMed1991

Molecular structure of mitochondrial cristae, solid state biochemistry and a simple theory of respiration-phosphorylation coupling.

Thanks to the improvement of preparatory procedures in electron microscopy during the 1960's the structural analysis of mitochondria has been extended to the molecular level leading to an almost 40-year-old misconception regarding mitochondrial structure being replaced by a more realistic version of the structure. The following observations are reviewed: 1) There are three different types of membranes in the mitochondria. 2) Geometrically regularly distributed circumscribed respiratory chain domains are surrounded by a continuous tricarboxylic acid cycle domain. 3) The cristae are compact structure with the enzyme molecules in a three-dimensional arrangement. 4) The active sites of most enzyme molecules are buried in the cristae and are exposed to an environment characterized as a biological solid state. 5) A water translocating mechanism removes water from the cristae maintaining a low water activity in the cristae. 6) The cristae are connected to the cytosol directly through proteinaceous pathways extending through the two surface membranes. 7) The matrix communicates with the cytosol by a route through the two surface membranes, bypassing the cristae. 8) The permeability of the inner surface membrane changes with the respiratory state. 9) The inner membrane particles can be made to appear under experimental conditions that prove their appearance to be an artifact. 10) A simple theory of respiration-phosphorylation coupling is proposed based on the solid state of the cristae. The theory agrees with the chemiosmotic theory with respect to the involvement of proton movement as basis for energy transduction, but differs with respect to how protons contribute to transduction.

Animals↗