bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstration of expanding cell populations in mouse pancreatic acini and islets
Authors: Tsubouchi Susumu , Kano Eiichi , Suzuki Harumi
Published: February 2005

The acinar and islet cells of the adult mouse pancreas were examined by radioautography after continuous infusion of 3H‐thymidine, for periods varying from 1 to 60 days, to determine whether they behaved like renewing or expanding cell populations. The labeling of both cell types increased with the duration of the continuous infusion and reached 2.22% and 12.0%, respectively, after 60 days. The rate of acinar and islet cell labeling was estimated from the regression line of the labeling index versus time and given as 0.039% and 0.20% cells per day, respectively.

The rate of cell labeling was relatively low in these acinar and islet cells in comparison to the relatively high rate in duct cells. Occasionally, acinar cell labeling was not uniform, showing high labeling in the outer peripheral region of a lobe and at the periphery of the islets. Both acinar and islet cells increased in number in the adult, and at a rate indicating they are expanding cell populations. Their doubling times were estimated as 2,564 days (7.0 years) and 500 days (1.3 years), respectively. Duct epithelial cell populations were dividing at a rate indicating that they are renewing cell populations.
Quantitative ultrastructure of histochemically identified avian skeletal muscle fiber types
Authors: Hikida Robert S.
Published: February 2005

A cryostat retrieval method and combined adenosine triphosphatase (ATPase) and acetylcholinesterase (AChase) method were used to study the ultrastructure and innervation of histochemically identified skeletal muscle fibers in different pigeon muscles. The Z‐line structure and volume percentage sarcotubular system were analyzed from different muscles selected for their composition by fiber type. Histochemically, three main fiber types were investigated: slow tonic fibers with a moderate ATPase activity after preincubation at acid or alkaline pH; fast‐twitch fibers that had high activity after alkaline treatment and low activity after acid preincubation; and a type considered to be slow‐twitch that had low activity after alkaline, and high after acid preincubation. Both the slow tonic and slow‐twitch fibers had multiple, en grappe innervation, while the fast‐twitch fibers had robust, single end plates. The Z‐line of the fast‐twitch and slow‐twitch fibers had a regular square lattice pattern, in contrast to the granular, nonlattice structure of the slow tonic Z‐line. The volume percentage sarcotubular system of the slow‐twitch fibers was intermediate between and significantly different from that of the fast‐twitch and slow tonic fibers. These correlative analyses suggest that the avian muscles contain not only the fast‐twitch and slow tonic fibers previously known, but also a slow‐twitch fiber that appears to be intermediate between the tonic and the mammalian slow‐twitch fiber type. Based on the abundance of the sarcotubular system, this fiber type appears to be fast‐contracting and ‐relaxing, in spite of being multiply innervated.
Histochemical and elemental localization of calcium in the granular cell subapical granules of the amphibian urinary bladder epithelium
Authors: Davis Walter L. , Jones Ruth Gwendolyn , Hagler H. K. , Farmer Gene R. , Goodman David B. P.
Published: February 2005

The ultrahistochemical analysis of apical granules in the epithelial cells, i.e., granular cells, of the amphibian urnary bladder using the N,N‐naphthal‐oylhydroxylamine procedure identified the presence of calcium in these structures. Subsequent analytical microscopy employing fresh‐frozen ultrathin cryosections for X‐ray microanalysis of the granules further confirmed the above histochemical findings. In addition to calcium, elemental analysis indicated the presence of magnesium, phosphorus, sulfur, silicon, potassium, and chlorine either within or in close proximity to the granules. The possibility that these granules function as subcellular compartments for the uptake and storage of calcium ions, in a way similar to mitochondria, and thus function in intracellular calcium homeostasis, is discussed. Additionally, a role for this cation in the secretion of granular glycoproteins, i.e., stimulus‐secretion coupling, is hypothesized.
Systematic distribution of muscle fiber types in the medical gastrocnemius of the laboratory mouse: A morphometric analysis
Authors: Brasseur Jeannette E. , Curtis Robin L. , Mellender James W. , Rimm Alfred A. , Melvin John L. , Sulaiman A. R.
Published: February 2005

Midbelly cross sections of the medial gastrocnemius muscle of young adult male laboratory mice were subjected to ATPase histochemistry with preincubation at pH 4.6. Through the use of a sampling grid and computer‐assisted morphometric analysis, 26 to 35% of the total muscle fibers were sampled and classified as type I, IIa, or IIb.

Photomicrographs (16×20 in.) of five muscles were divided into octants according to a standardized procedure. Total fiber counts and percent of fibers sampled were determined. Variability of sample size per octant was noted, but when averaged across entire muscles, it was in all instances greater than 33%. Fiber type frequency per octant was tested for goodness of fit to a random model by means of a chi‐square statistic for equal expected frequencies. Deviation from random fiber type frequency was significant at the P = 0.001 level for every muscle. More importantly, when these data were pooled and again tested using the same method, the probability estimate was less than P = 0.001. This established that the variations in the fiber type proportions found in each mouse followed a common pattern.

The systematic fiber type distribution confirmed by these morphometric and statistical methods supports the impression expressed by many muscle biologists that this muscle displays a consistent and complex intramuscular organization.
Improved ultrastructural preservation of epiphyseal chondrocytes by the freeze‐substitution method
Authors: Akisaka Toshitaka , Subita Gus Permana , Kawaguchi Hiroyuki , Shigenaga Yoshio
Published: February 2005

The ultrastructure of epiphyseal chondrocytes was studied following quick‐freezing and freeze‐substitution, and was compared to that of cells fixed with aqueous aldehydes. The former approach provided an improved ultrastructural preservation whereby every type of chondrocyte exhibited a smoother cell contour. The plasma membrane as well as intracytoplasmic membranes revealed a trilaminar substructure. The intracytoplasmic ground substance was composed of flocculent materials which were in direct contact with the inner leaflet of the plasma membrane. Within the extracellular matrix the proteoglycan network adhered to the outer leaflet of the plasma membrane. Whenever cellular shrinkage took place, the flocculent matrix within the cytoplasm and the proteoglycan network in the pericellular matrix disappeared. The contents of the RER, the Golgi apparatus, and the intracellular vesicles and vacuoles were well retained. In the proliferative zone, the Golgi saccules of young cells contained a thread‐like structure showing a clear periodicity. The cytoplasmic vesicles and vacuoles showed marked variation in their electron density. Intramitochondrial granules were sensitive to aqueous treatments, as evidenced by the observation that they disappeared after either floating on water or staining with aqueous solution. In the calcifying zone, mitochondrial granules were noted within hypertrophic chondrocytes, a feature that was not observed following conventional processing. Cytoskeletal elements were well preserved in all types of cells. A dense microfilamentous network occupied the pericellular cytoplasm. Bundles of microfilaments were seen in the cellular peripheral processes. Microtubules were distributed throughout the cytoplasm, and the Golgi complex was intimately associated with the microtubule network; it appears that the secretory processes are involved with the microtubules.
Development of preimplantation rabbit embryos after in‐vitro culture and embryo transfer: An electron microscopic study
Authors: Hegele‐Hartung Christa , Fischer Bernd , Beier Henning M.
Published: February 2005

Compared to in vivo development, in vitro culture of mammalian embryos results in developmental retardation. To study the potential of reversibility of growth retardation we investigated ultrastructurally day 3 rabbit embryos after 1 day in vitro, and cultured embryos that were transferred after culture into recipient rabbits for 1 day. Morphology was compared with ultrastructure of noncultured controls. The noncultured embryos were compacted morulae; the characteristic ultrastructure is described in detail. After 1 day in culture, morulae had developed into early blastocysts. However, unlike the results in vivo, expansion of the blastocysts did not occur and some of the cultured embryos developed trophoblast herniations. In all cultured embryos morphological signs of degeneration were seen with swollen mitochondria, with a dense, granular appearance of the cytoplasm, and with an increase in number of lysosomes. Transfer of cultured blastocysts into uteri of day 3 pseudopregnant recipients resulted in ultrastructurally intact and expanded blastocysts. Transfer into uteri of day 4 pseudopregnant recipients and into uteri of nonpregnant recipients, however, did not yield reversibility of the unphysiological features suffered during the previous time in culture. Although blastocysts were well expanded, distinct signs of injury to the blastomeres were present, proceeding from loss of complete blastomeres to structural changes such as large lamellar structures, dilation of smooth endoplasmic reticulum and Golgi complexes, and clumping of mitochondria. We conclude that developmental retardation during in vitro culture is accompanied by distinct morphological changes. As soon as 24 hr after transfer, these changes can be reversed. This compensation, however, is achieved only if embryos are transferred into recipients that are adapted to the embryo's developmental stage, which is not identical to the embryo's chronological age. Our findings demonstrate that the period of 24 hr of in vitro development matches only a few hours of in vivo development.
Changes in the distribution of microtubules and intermediate filaments in mammalian Sertoli cells during spermatogenesis
Authors: Amlani S. , Vogl A. W.
Published: February 2005

We have studied the distribution of microtubules and intermediate filaments in mammalian Sertoli cells during spermatogenesis. The arrangement of microtubules was determined, by indirect immunofluorescence, in ground squirrel testes that were (1) fixed, mechanically fragmented, and attached to polylysine‐coated slides, and (2) fixed, embedded in polyethylene glycol, and sectioned. Intermediate filament patterns were determined, also by indirect immunofluorescence, in sections of unfixed rat testis. Results from these studies were confirmed and extended using electron microscopy.

Microtubules first become evident in lateral processes that embrace round spermatids. When spermatids elongate and become situated in apical crypts of Sertoli cells, the microtubules become oriented parallel to the long axis of Sertoli cells and surround the crypts. As spermatids mature and acquire a saucer shape, apical microtubules progressively concentrate in Sertoli cell regions adjacent to the acrosome and eventually form discrete C‐shaped structures that disappear during spermiation.

Intermediate filaments in rat Sertoli cells are centered around the nucleus. From perinuclear regions, filaments extend toward desmosome‐like junctions with early spermatogenic cells and into the apical cytoplasm where they have a transient association with crypts containing elongate spermatids. Filaments amongst crypts are most evident in early stages of the spermatogenic cycle when apical crypts are situated deep within the epithelium. They become less evident and eventually disappear as spermatids assume a more apical position. Our fluorescence studies and ultrastructural analyses indicate that the association of intermediate filaments with crypts is specific to regions adjacent to the dorsal or convex aspect of spermatid heads. In these regions, approximately 8 to 12 uniformly aligned filaments are intimately associated with actin filaments in ectoplasmic specializations surrounding the crypts.

We conclude that, like actin, the distribution of microtubules and intermediate filaments changes in Sertoli cells during spermatogenesis. The distribution of microtubules correlates with the irregular columnar shape of Sertoli cells. We suspect that the apically situated intermediate filaments may play a role in anchoring or positioning Sertoli cell crypts deep within the epithelium during the early stages of the spermatogenic cycle.
Ultrastructural study of the semicircular canal cells of the frog Rana esculenta
Authors: Oudar Olivier , Ferrary Evelyne , Feldmann Gérard
Published: February 2005

The ultrastructure of the nonsensory cells (dark cells, transitional cells, and undifferentiated cells) of the frog semicircular canal was studied by using transmission electron microscopy in an attempt to correlate the structure with the functions of these epithelial cells. All the nonsensory cells were linked by tight junctions and desmosomes; this suggested that there is little paracellular ionic transport from perilymph to endolymph. In the dark cell epithelium, the apicai intercellular spaces were dilated; in the basal part, numerous basolateral plasma membrane infoldings, containing mitochondria, delimited electron‐lucent spaces. The undifferentiated cells and the transitional cells were devoid of any basal membrane infolding. Surrounding the semicircular canal, very flattened and interdigitated mesothelial cells constituted a thin multilayer tissue which limited the perilymphatic space. The morphological aspect of the dark cells suggests that they may play a role in the secretion and/or in the reabsorption of endolymph, which bathes the apical pole of these cells. The undifferentiated and transitional cells can play a role in the maintenance of the endolymphatic ionic composition because of their apical tight junctions and desmosomes.
Neutrophil lactoferrin content: Variation among mammals
Authors: Barton James C. , Parmley Richard T. , Butler Thomas W. , Williamson Sue , Mackenzie Sandra , Chandler David B. , Blackburn Warren , Heck Louis W.
Published: February 2005

Lactoferrin (Lf) in blood and/or marrow neutrophils was semiquantified using indirect immunofluorescence technique in nine mammalian species. Neutrophil iron‐binding reactivity (NFeBR), which corresponds primarily to Lf, was also visualized and semiquantified using functional cytochemical (FeNTA‐AF) technique at the light microscopic level in these nine and in an additional fifteen mammalian species, and in selected species at the ultrastructural level. Neutrophil immunoreactive Lf was positively correlated with total cellular and granule content of NFeBR among these nine species, and with previously reported concentrations of neutrophil Lf quantified by radioimmunoassay. Relative levels of Lf in neutrophil extracts from rat, hamster, and human were confirmed using SDS‐polyacrylamide gel electrophoresis and immunoblotting. Relatively high levels of immunoreactive neutrophil Lf and/or NFeBR were observed in carnivores (ten species) and primates (six species). Among rodents (five species), the levels were variable, and the artiodactyls (four species) studied had low levels. These results demonstrate that neutrophil Lf levels vary widely among mammalian species. In addition, FeNTA‐AF technique provides a rapid means of evaluating animals for relative quantities of neutrophil Lf.
Structural heterogeneity within the pulmonary microcirculation of the normal rat
Authors: DeFouw David O.
Published: February 2005

Extra‐alveolar microvessels of the rat were described previously as nonmuscular, partially muscular, and muscular (Hislop and Reid, 1978). Based on these structural criteria, the present morphometic results present evidence that mean thickness of the endothelium was significantly greater in the muscular microvessels than in each of the other microvessel categories. The percentage of endothelial surface occupied by attenuated segments (20–30 nm maximal thickness) was greatest in the nonmuscular and partially muscular microvessels. Mean plasmalemmal vesicle diameters were consistent throughout the microvascular units. Vesicle numerical densities, however, were significantly greater in the alveolar capillary endothelium than in endothelia of the nonmuscular, partially muscular, and muscular microvessels. Endothelial vacuoles (diameters greater than 150 nm) were not observed in either the capillaries or the nonmuscular microvessels. Mean diameters and numerical densities of vacuoles observed in endothelia of the partially muscular and muscular microvessels were, however, statistically similar. Subclassification of the partially muscular and muscular microvessels by ultrastructural characteristics as arterioles or venules (Rhodin, 1978; Michel, 1982) served to identify greater numerical densities of vesicles in the endothelium of venules than that of the arterioles. As expected, mean thicknesses of the periendothelial connective tissue spaces varied directly with the relative muscularity of the respective microvessels. Based upon the morphometric data presented in this study, future investigations of pulmonary microvascular functions should include considerations of the observed regional variations of endothelial cell ultrastructure.
Endocytosis of parotid salivary proteins by striated duct cells in streptozotocin‐diabetic rats
Authors: Lotti Lavinia V. , Hand Arthur R.
Published: February 2005

Salivary gland striated duct cells play an important role in the modification of primary saliva by secretion and reabsorption of electrolytes, and secretion of glycoproteins. Recent observations have shown that in the rat parotid gland these cells are able to internalize exogenous proteins, e.g., horseradish peroxidase and ferritin, from the ductal lumen. In rats made diabetic by injection of streptozotocin, dense vacuoles and crystalloids are present in the apical cytoplasm of parotid striated duct cells. In this study we utilized electron microscopic immunocytochemistry to determine if these vacuoles and crystalloids contain acinar secretory proteins. At various times after induction of diabetes by streptozotocin (65 mg/kg), the parotid glands were fixed in a glutaraldehyde‐formaldehyde mixture, postfixed in OsO4, and embedded in epoxy resin. Thin sections were immunolabeled with antibodies to protein B1 (Ball et al., 1988) and α‐amylase (Baum et al., 1982) using a modification of the Protein A‐gold technique (Bendayan and Duhr, 1986). With antibody to B1, label was localized in the secretory granules of acinar and intercalated duct cells of both normal and diabetic rats. In striated duct cells of diabetic rats, label was present over the electron‐dense vacuoles but not over the crystalloids. Since crystalloids appear to form within the vacuoles, their lack of reactivity may indicate degradation of the internalized protein. The same distribution of label was found with antibody to amylase except for the intercalated duct granules, which were unlabeled in both control and diabetic animals. These results demonstrate that striated duct cells take up salivary proteins from the lumen and that the endocytosis of some secretory proteins from the saliva may be a significant function of these cells in certain pathological conditions.
Origin and propagation of elastogenesis in the developing cardiovascular system
Authors: Rosenquist Thomas H. , McCoy Judy R , Waldo Karen L. , Kirby Margaret L.
Published: February 2005

Ectomesenchyme derived from cardiac neural crest is critical to aorticopulmonary septation in the heart. However, any unique contribution of the cardiac ectomesenchyme to the extracellular matrix of the conotruncus has not been demonstrated previously.

In this study the chronology and topography of soluble tropoelastin (STE) and the aldehyde‐rich protein (ARP) of the elastic connective tissues have been examined in the chick embryo, stages 21–38, and in the quail‐chick chimera, stages 24–35 (quail neural fold grafted onto a chick embryo). STE was located with immunofluorescence histochemistry, and ARP with Schiff's reagent. With these procedures prevenient site of elastin synthesis are observed readily.

The results show that the myocardium proper appears to have a role in the instigation of elastogenesis and in elastic fiber orientation; that the mesenchymal cells whose matrix contains elastic fibers are ectomensenchymal, of neural crest origin; and that elastin is deployed in an orderly proximal‐distal sequence.

It is hypothesized that elastogenesis is a critical event in aorticopulmonary septation.
Acute and chronic reactions of dental sensory nerve fibers to cavities and desiccation in rat molars
Authors: Byers M. R. , Närhi M. V. O. , Mecifi K. B.
Published: February 2005

We have studied the effects of air drying of exposed, acid etched dentin on the sensory innervation of rat molars. In the acute series of experiments, trigeminal nerve fibers were labeled by axonal transport of radioactive protein prior to the dentin exposure and desiccation, the anesthetized rats were fixed by aldehyde perfusion 10 min later, and the teeth were prepared for autoradiography. The results confirmed the hydrodynamic theory by showing outward movement of labeled nerve material in response to dentinal drilling and desiccation. It also showed that some odontoblasts could be separated from the dentinal nerve fibers. In the chronic series, teeth were injured 25 h, 5–7 days, or 21 days prior to fixation and nerves were labeled during the last 24 hours; the surviving vital nerve fibers were evident because of their axonal transport of the radioactive label. In that series, sensory nerve fibers were found to have been lost from areas with newly‐formed reparative dentin, or from dentinal tubules that had lost their odontoblasts. In the teeth injured 25 h, 5–7 days, or 21 days earlier, an abnormal nonneuronal labeling occurred 0.2–0.3 mm into injured dentin. Our results are discussed in relation to the hydrodynamic theory, nerve‐odontoblast interactions, differences between shallow and deep cavity injuries, altered nerve location in response to pulpal or dentinal injury, and characteristics of the pulp‐dentin border.
Angiogenesis in the developing corpus luteum of pregnant rats: A stereologic and autoradiographic study
Authors: Meyer Geoffrey T. , McGeachie John K.
Published: February 2005

Within the adult mammalian ovary, angiogenesis is associated with development of the corpus luteum (CL). In this study, developing luteal tissue was examined to determine whether its vascularization involves endothelial cell replication and to what extent this proliferation contributes to forming new capillaries. Five rats each at 12, 24, 36, 48, 60, 72, 84, and 96 hr of gestation were given a subcutaneous injection of tritiated thymidine (specific activity 5 Ci/M; 1 uCi/g body weight). One hour later they were anesthetised with sodium pentobarbitone, and the left ovary was processed for light microscopy. Sections were cut through each ovary until three newly formed CL were recognized; a 1‐μ section was taken from the maximum diameter of each CL and processed for autoradiographic demonstration of thymidine labeling in endothelial cell nuclei. The same sections were also examined with stereological techniques to quantitate growth of the vascular compartment. The results show that 36.1 ± 5.7% of endothelial cells of invading capillary sprouts divide within 12 hr of ovulation; at 24 hr, 29.0 ± 2.8% are dividing. Within 12 hr after ovulation, blood vessels occupied 5.9 ± 1.4% of the peripheral space of the ruptured follicle but only 1.6 ± 0.5% in the center. However, by 36 hr these respective values were 9.3 ± 1.6% and 8.4 ± 1.9% A further peak in endothelial‐cell replication (31.2 ± 5.4%), early on the 3rd day of gestation, corresponded to the very extensive anastomoses within the capillary bed established between this time (13.6% vascularity) and late on the 4th day (about 23%). We conclude that replication of endothelial cells from capillary sprouts accounts for substantial angiogenesis in the developing CL. Labeling in endothelium of the developing CL and the capsule surrounding the CL were greater than in CL of previous cycles and vessels within the ovarian stroma. This finding supports the view that there may be some local control of endothelial‐cell replication.
Development of mitochondrial helical sheath in the middle piece of the mouse spermatid tail: Regular dispositions and synchronized changes
Authors: Otani Hiroki , Tanaka Osamu , Kasai Kei‐Ichiro , Yoshioka Takafumi
Published: February 2005

Morphologic changes in the development of the mitochondrial helical sheath in the mouse spermatid tail were examined with the scanning electron microscope (SEM) using the osmium‐DMSO‐osmium method and classified into several stages. During late spermiogenesis, spherical mitochondria gathered around the forming spermatid tail. The shape of these mitochondria gradually changed from spheroid to long and rod‐like. Mitochondria first were arranged in four longitudinal rows (stage 1) that twisted dextrally, and the mitochondria began to stagger (stage 2). They became elongated and arranged into a staggered pattern; they then attached to each other in an end‐to‐end fashion to form a sinistral double helix around the core of the axoneme (stage 3). These end‐to‐end contacts were observed in every second gyre on the four lines surrounding the core of the axoneme at stage 3. Mitochondria further elongated and end‐on touching appeared with every third gyre on the five longitudinal lines that surround the core of the axoneme (stage 4). The direction of the helix, always sinistral, was clearly discernible only in the later stages. Disposition of the mitochondria in the spermatid tail was regular throughout development, which indicates that these mitochondria elongate simultaneously and also at the same rate. On any given cracked surface of the seminiferous tubule, spermatid tails with the same stage of mitochondria predominantly were observed. This ultrastructural finding appears compatible with the histologic synchronism, (termed the “wave”) in differentiating germ cells.
Origin of aortic cell clusters in the chicken embryo
Authors: Olah Imre , Medgyes J. , Glick Bruce
Published: February 2005

In 3‐day‐old embryos the aortic cell clusters formed two parallel ridges in the ventrolateral part of the aorta. The border of the somato‐ and splanch‐nopleures close to the aorta showed a very intensive cell proliferation and a cell emigration up to the aorta. This cell flow and the bilateral appearance of the intraaortic ridges suggested that the aortic cell clusters originated from the coelomic epithelium. This intraembryonic hemopoietic stem cell formation from the splanchnopleure was comparable to that of the blood island formation in the yolk sac from extraembryonic splancnopleure. The appearance of the white blood cells and definitive erythrocytes with adult‐type hemoglobin was preceded by the aortic cell clusters. We concluded that the stem cells of the adult‐type blood developed from the aortic cell clusters whereas the blood islands of the yold sac may contribute only the primitive red blood cells.
Extragonadal distribution of primordial germ cells in the early chick embryo
Authors: Nakamura Masao , Kuwana Takashi , Miyayama Yukihiko , Fujimoto Toyoaki
Published: February 2005

Chick primordial germ cells (PGCs), after separation from the endoderm in early embryonic development, temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. It has been noted by some authors that some PGCs are present in extragonadal sites in some vertebrates. In the present study, we examined the distribution and localization of PGCs in extragonadal sites in the chick embryo. PGCs were identified by periodic acid‐Schiff staining with light microscopy. In embryos at stages 20–24 (PGCs are in the settlement stage in the gonadal primordium), approximately 20% of the total number of PGCs were observed in extragonadal regions. Approximately 90% of these ectopic PGCs were found in the head, mainly in the mesenchyme surrounding the neural tube. Even at stage 14 when PGCs were usually circulating in the blood vessels, some of the PGCs had emerged from the blood vessels and were detected in the extragonadal site. The pattern of distribution of ectopic PGCs in the head area is probably attributed to the earlier, dominant development of the capillay network, and to the sluggish capillary blood flow in that region, which allows intravascular PGCs to escape into the tissue.
Fiber sizes and histochemical characteristics of the rectus abdominis muscle of the rabbit under conditions of pregnancy and mechanically induced stress
Authors: Costerbosa G. Lalatta , Barazzoni A. M. , Lucchi M. L. , Bortolami R.
Published: February 2005

Histochemical properties and muscle fiber diameters of the rectus abdominis (RA) muscle of the female rabbit were compared with those of RA muscle of (1) pregnant females at term of pregnancy (30 days); (2) pregnant females in which the stretch on the abdominal wall natural to pregnancy was artificially prolonged with a 40‐day period of intraabdominal appliance; (3) virgin females subjected to intraabdominal appliance for 30, 45, 60, and 70 days. The RA muscle of the control female rabbits is composed of 29.73% type I, 12.13% type IIA, 57.59% type IIB, and 0.54% type IIC fibers. The stimulation on RA muscle due to either normal pregnancy or implant in virgin females provoked changes in muscle fiber diameters only; with the normal pregnancy plus the subsequent period of mechanical stimulation, changes occurred not only in muscle fiber diameters, but there was also a significant increase in the percentage of type I fibers and a concomitant decrease of type IIA and IIB fibers.

The fiber‐type pattern in the RA muscle of male and female rabbit also was compared. The RA muscle of the male rabbit showed more type IIA and less Type IIB fibers than found in that of the female. Type I fibers were larger in the female, but type IIA fibers were larger in the male. In addition, male rabbits also were subjected to 30, 45, 60, and 70 days of RA muscle stimulation by means of an intraabdominal appliance to ascertain if the influence of such stimulation upon the RA muscle differed between the two sexes. Some differences in the response of the male RA muscle were noted.
Quantitation of structural features characterizing weight‐ and less‐weight‐bearing regions in articular cartilage: A stereological analysis of medical femoral condyles in young adult rabbits
Authors: Eggli Peter S. , Hunzinker Ernst B. , Schenk Robert K.
Published: February 2005

The structural organization of articular cartilage from the medial femoral condyle of young adult rabbits has been examined after processing according to an improved fixation procedure. By using recently developed stereological methods, a quantitative analysis of chondrocyte number, surface area, volume, and matrix volume per cell was carried out in the light microscope; at the electron microscopic level, quantities of cytoplasmic components within chondrocytes (including organelles) were estimated. These measurements were made for each of the four zones from the (articular cartilage) surface down to the tidemark, and the results (for each zone) were compared between weight‐ and less‐weight‐bearing regions.

In general, articular cartilage revealed considerable heterogeneity in structure throughout its depth. The number of cells per unit volume is maximal beneath the surface and decreases towards the tidemark. The size of chondrocytes, and the mean matrix volume surrounding each, increases from the surface toward the deeper zones. Comparison between weight‐ and less‐weight‐bearing regions reveals striking differences. The numerical volume density of cells in the superficial zone of regions bearing high physiological load is less than half of that in less‐weight‐bearing regions, chondrocyte death being principally responsible for this reduction. A comparison between the midzones of weight‐ and less‐weight‐bearing areas reveals that the former is characterized by a decrease in cell density and an approximately threefold increase in cell size in relation to the latter. The increase in cell volume is attributable principally to an accumulation of intermediate filaments and glycogen particles, and represents an adaptation to increased functional requirements. Near the tidemark, numerical volume densities of chondrocytes in both weight‐ and less‐weight‐bearing locations are similar, but the larger cell size in the former still persists.
Budding of small vesicles from the rough‐surfaced endoplasmic reticulum in secretory ameloblasts of rat molar tooth germs
Authors: Matsuo Saburou , Takano Yoshiro , Wakisaka Satoshi , Ichikawa Hiroyuki , Nishikawa Shinji , Akai Michio
Published: February 2005

The budding of small vesicles from the rough‐surfaced endoplasmic reticulum (rER) was examined in the secretory ameloblast of rat molar tooth germs by ordinary fixation or prolonged osmium fixation. The budding of small vesicles from the rER was observed not only at the special region (transitional region) of the rER system, which abutted on the cis‐face of the Golgi apparatus, but also at other regions of the rER in the secretory ameloblast. Small vesicles (presumed to be transitional vesicles) were adjacent to the rER, which also showed budding of vesicles. After prolonged osmium treatment, osmium deposits appeared in small vesicles, as well as in the cisternae of the cis saccule of the Golgi apparatus. Small vesicles containing osmium deposits were located at various regions of the cell, including the cis‐face of the Golgi apparatus. These findings indicate that the budding of small vesicles from the rER is not restricted to the transitional region of the rER system of the secretory ameloblast, but is found at various regions of the cell. This indicates that newly synthesized proteins may be transferred from the rER cisternae to the transitional vesicles not only in the transitional region of the rER system adjacent to the Golgi apparatus, but also in other regions of the secretory ameloblast.
A survey by scanning electron microscopy of the extracellular matrix and endothelial components of the primordial chick heart
Authors: Drake Christopher J. , Jacobson Antone G.
Published: February 2005

Scanning electron microscopy was used to study the morphogenesis of the primitive embryonic chick heart (stage 5 late primitive streak through stage 9+). Components of the developing heart (myocardium, endocardial endothelium, and extracellular matrix) were viewed from the ventral surface after removal of the endoderm.

The myocardial component of the heart can first be seen by light microscopy at stage 5 as two darker oval‐shaped areas located on either side of the embryonic axis in the cranial region of the embryo. Scanning electron microscopy demonstrates that as early as stage 6 an area of extracellular matrix, enriched in comparison to more lateral and medial splanchnic mesoderm, can be identified ventral to the myocardial primordium.

As heart formtion progressed we observed primordial endothelial elements in the splanchnic mesoderm lateral to the myocardial primordia. By late stage 7 these lateral primordial elements had anastomosed into small, loose plexuses. This process of anastomosis progressed rapidly, and by stage 8 the entire cranial surface of the myocardial primordium was covered with vascular plexuses. By late stage 8 the progressive fusion of these plexuses resulted in the formation of large multiple tubular elements near the midline. More medially the fusion of tubular elements resulted in a continuous endothelial sheet at the midline.
Horseshoe kidney: A new theory on lts embrogenesis based on the study of a 16‐mm human embryo
Authors: Doménech‐Mateu J. M. , Gonzalez‐Compta X.
Published: February 2005

We studied a human embryo of 16 mm crown‐rump (CR) length in excellent condition with a horseshoe kidney malformation. An exhaustive study of this specimen and a review of published material on the human embryo brings us to propose a new theory on the embryogenesis of this malformation. The most commonly accepted theory consists of a mechanical interpretation based on the relation between the metanephroi and the umbilical arteries during the development of the latter. Nevertheless, in those cases where renal parenchyma constitutes the isthmic region, we believe that these arise from nephrogenic cells that have migrated across the primitive streak in the final phase of gastrulation and thus arise from the posterior nephrogenic area of the epiblast.
Iron and aluminum deposition in the meninges of the lamprey: Identification of an aluminum‐ferritin inclusion body
Authors: Youson J. H. , Sargent P. A. , Pearce G. W.
Published: February 2005

The meningeal tissue of the brain and spinal cord of larval and juvenile adults of lampreys (Petromyzon marinus) was examined by routine electron microscopy, electron microscopic histochemistry, and electron‐probe x‐ray microanalysis to locate sites of iron deposition. A magnetometer was used for identification of ferromagnetic iron. Ferritin particles, representing ferric iron, are present in abundance within the cytoplasmic matrices and in dense bodies of meningeal cells of both the brain and spinal cord of larvae and juveniles. These round cells of the meninges also contain abundant glycogen and lipid. Small quantities of ferrous iron are associated to the latter inclusion. Aluminum deposits are present within an electrondense material of many ferritin‐containing inclusions of meningeal cells of the larval brain. Ferromagnetic material was not detected in larval and upstream‐migrant lampreys. The deposition of iron and aluminum in the meninges of lampreys may be related to physiological and environmental factors, respectively, and/or to an important interaction between the two metals.
The ultrastructure of ruffini endings in the periodontal ligament of rat incisors with special reference to the terminal schwann cells (K‐cells)
Authors: Maeda Takeyasu , Sato Osamu , Kobayashi Shigeo , Iwanaga Toshihiko , Fujita Tsuneo
Published: February 2005

The Ruffini endings and associated cells in the periodontal ligament of rat incisors were investigated by means of immunohistochemistry for glia‐specific S‐100 protein and electron microscopy. Numerous Ruffini endings, which were immunoreactive for S‐100 protein as well as for neurofilament protein, were distributed in the alveolus‐related part of the lingual periodontal ligament. In electron microscopy, the Ruffini endings displayed expanded axoplasmic spines filled with a large number of mitochondria and neurofilaments; some of the spines directly contacted the surrounding collagen fibers via fingerlike projections. The axoplasmic spines and Schwann sheath, for the most part, were covered alternately by single or multiple layers of the basal lamina.

Several rounded cells showing S‐100 immunoreactivity occurred in the vicinity of the Ruffini endings. The rounded cells associated with Ruffini endings possessed a kidney‐shaped nucleus and enveloped the axoplasmic spines with their cytoplasmic processes. From these morphological features, the cells in question were identified as the K‐cells described by Everts et al. (1977). These K‐cells developed Golgi apparatus and rough endoplasmic reticulum, suggesting active synthesis of proteins. Immunohistochemistry at the electron microscopic level revealed an intense immunoreactivity for S‐100 protein in the cytoplasm of the K‐cell and led to a conclusion that the K‐cells were terminal Schwann cells associated with Ruffini endings, presumably corresponding to the lamellar cells in the inner bulb of sensory corpuscles.
Immunoperoxidase localization of prostatic inhibin peptide in human, monkey, dog, and rat prostates
Authors: Garde Seema V. , Sheth Anil R.
Published: February 2005

A comparative study on the localization of prostatic inhibin peptide was carried out by the immunoperoxidase technique in prostates of humans, bonnet and langur monkeys, marmosets, dogs, and rats. A positive reaction was observed in the prostatic epithelial cells of humans, in all three species of monkeys, and in the rat, while the dog prostate did not exhibit any reaction. These observations indicate a close immunological similarity among human, monkey, and rat prostatic inhibin peptides.
Mammalian frontal diploic vein and the human foramen caecum
Authors: Thewissen J. G. M.
Published: February 2005

The course of the frontal diploic vein in the mole Talpa and the tree shrew Tupaia is described and compared to the frontal diploic vein of other mammals. The frontal diploic vein in Talpa and Tupaia connects the dorsal sagittal sinus to the veins of the orbit and has an emissary function. In certain other mammals it has a diploic function and may drain towards the orbit (e.g., Orycteropus) or towards the dorsal sagittal sinus (e.g., Didelphis). The frontal diploic vein of these mammals is not homologous to the vein of the human foramen caecum, but to the human frontal diploic vein. The vein of the formen caecum is a problematic structure: its incidence in embryos and children is not clear.
Body weight gain as related to craniofacial and calvarial volumetric changes in growing rabbits
Authors: Alberius Per , Malmberg Martin
Published: February 2005

This investigation was conducted to evaluate the relationship between calvarial and craniofacial volumetric growth relative to body weight gain. Ten male New Zealand white rabbits received spherical tantalum bone markers in the nasal, frontal, parietal, and temporal bones: a minimum of two in each bone segment. The animals were followed from age 32 to 144 days using a roentgen sterophotogrammetric system and an accurate scale. Implant stability was checked at each sterometric examination. Sutural growth and volumetric changes were computed and correlated to weight increase. Successive calvarial and craniofacial polyhedron expansion, as well as weight, showed considerable variability and interindividual variation throughout the observation period. Calculated coefficients of determination, linear regressions, and the correlation coefficients for each age interval demonstrated weak correlations, especially for calvarial to weight data. Consequently, this study suggests a low dependence of calvarial volumetric growth, reflecting the neural mass expansion on body weight development. Thereby, further indications of the low reliability of weight as a parameter of general health evaluation was provided.
Glyoxylate cycle in the epiphyseal growth plate: Isocitrate lyase and malate synthase identified in mammalian cartilage
Authors: Davis Walter L. , Jones Ruth G. , Farmer Gene R. , Matthews J. L. , Goodman David B. P.
Published: February 2005

Peroxisomes were identified in chondrocytes from all zones of the mammalian epiphyseal growth plate by using light microscopic techniques for the cytochemical demonstration of catalase, the marker enzyme for these organelles. Additional cytochemistry showed the presence of malate‐synthase‐positive structures within the chondrocytes. The latter enzyme, also associated with peroxisomes, is unique to the glyoxylate shunt, a metabolic pathway thought to be absent in vertebrate tissues. The glyoxylate cycle allows the net conversion of lipid to carbohydrate, i.e., gluconeogenesis. Biochemical studies on growth plate cartilage indicate that this tissue has the capacity to carry out cyanide‐insensitive B‐oxidation of fatty acids. The latter takes place in a nonmitochondrial compartment, most likely the peroxisomal compartment. Additionally, both of the unique enzymes associated with the glyoxylate cycle, i.e., isocitrate lyase and malate synthase, were also identified in a cell‐free homogenate of this cartilage. These studies indicate that cartilage, a poorly vascularized tissue characterized by its low oxygen tension and anaerobic glycolysis, may have the capacity to convert lipid to carbohydrate, i.e., gluconeogenesis via the glyoxylate pathway. In this way, cartilage may be unique among mammalian tissues.
Heart contains receptors for dihydrotestosterone but not testosterone: Possible role in the sex differential in coronary heart disease
Authors: Sheridan Peter J. , McGill Henry C. , Aufdemorte Thomas B. , Triplett Robert G. , Holt Richard G.
Published: February 2005

The sex differential in coronary heart disease is well documented but poorly understood. Previous studies have demonstrated receptors for dihydrotestosterone (DHT) in the myocardium and smooth muscle cells of arteries from a number of species. In this autoradiographic study, we further investigated and characterized the in vivo uptake and retention of the androgen binding in the male baboon. Adult castrated male baboons were injected with 1 μg/kg bw 3H‐testosterone; 1 hr after the injection, the animals were rapidly exsanguinated while under anesthesia. The heart and arterial system were removed and processed for autoradiography. As a negative control, one animal received both 3H‐testosterone and 100‐fold unlabeled testosterone. For positive controls, the pituitary gland, prostate, seminal vesicles, and other tissues were also removed and processed for autoradiography. In contrast to our previous finding with 3H‐DHT, no nuclear uptake and retention of 3H‐steroid was found in any of the cells in either the heart or the arterial system. In the positive control tissues, pituitary gland, prostate, seminal vesicles, and others, a very distinct nuclear uptake and retention of 3H‐steroid was observed, which was completely inhibited by the simultaneous injection of 100‐fold unlabeled testosterone. In the binding study, Scatchard analysis of the cytosol prepared from a 17‐year‐old female baboon demonstrated levels of androgen receptor (as determined by the use of radiolabeled R1881) comparable to that found in young adults. The results of these studies suggest that, in contrast to the generally accepted hypotheses, (1) circulating DHT, not testosterone, is the androgenic hormone that interacts with the cardiovascular tissue of the baboon and (2) there are separate receptors for testosterone and DHT in different tissues rather than a single receptor capable of binding both steroids.
Banding Patterns in rat incisor enamel stained by histochemical complexing methods for calcium
Authors: McKee M. D. , Warshawsky H.
Published: February 2005

A characteristic banding pattern can be visualized at the surface of the rat incisor in the maturation zone of amelogenesis by staining with glyoxal bis(2‐hydroxyanil) (GBHA). Other banding patterns can be obtained with certain histological and fluorochrome stains and by radioautography following 45Ca injection. In this study, several histochemical reagents known to complex with different states of calcium were used to stain the surface of enamel. Rat incisors were quickly dissected and immediately immersed in solutions containing the following calcium‐binding reagents: arsenazo III, calmagite, murexide, N, N‐naphthaloylhy‐droxylamine, and calcein. Routinely, one contralateral lower incisor from each pair was counterstained with GBHA in order to relate each of the staining patterns to the banded distribution of maturation ameloblasts that is reflected by the characteristic GBHA staining pattern in the enamel. Each of the reagents used in this study demonstrated a staining pattern consisting of a series of broad bands running transversely and obliquely across the enamel. In all cases, the dyes stained predominantly that enamel associated with ruffle‐ended ameloblasts, i.e. enamel left unstained by GBHA. Some of the reagents also stained enamel in the secretion zone. The appearance and distribution of the staining patterns reflect the banded distribution of maturation ameloblasts and appear to be controlled on a time scale related to the rapid modulation of these cells.