bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber components of the recurrent laryngeal nerve of the rat: A study by light and electron microscopy
Authors: Dahlqvist Åke , Carlsöö Bengt , Hellström Sten 
Published: February 2005

AbstractA quantitative study by light and electron microscopy of the recurrent laryngeal nerve (RLN) of the rat has been performed. The diameter of the myelinated fibers displayed a bimodal pattern, with a pronounced peak at 2–3 μm, and with a second peak at 4.5–7 μm. The number of small fibers was reduced at the termination of the nerve, indicating that many of the small fibers are distributed to the trachea and oesophagus as the nerve ascends in the neck. Upon comparison, no difference between right and left side was noted in numbers of myelinated fibers. The RLN was also found to contain numerous unmyelinated fibers. Most of these fibers were of the diameter size range 0.2–0.6 μm. The unmyelinated fibers constituted about 50–60% of all axons in the RLN.
Epidermal growth factor delays the development of the epidermis and hair follicles of mice during growth of the first coat
Authors: Moore G. P. M. , Panaretto B. A. , Robertson D. 
Published: February 2005

AbstractThe structure of the epidermis and hair‐follicle bulbs and the proliferative activities of their component cells were studied in the midside skin of male mice treated with epidermal growth factor (EGF) or saline during formation of the first coat (days 0–21). The epidermis was thickest at birth, but in control animals became progressively thinner as cell size and the number of layers of granular and cornified cells were reduced. EGF treatment from birth resulted in a thickening of the epidermis at 5 days of age, and at 5 and 8 days the histological appearance was strikingly similar to that on the day of birth. At 12 and 21 days the structure of the epidermis of EGF‐treated mice more closely resembled that of contemporaneous controls. The mitotic and labeling indices of the basal cells of control epidermis declined throughout the sampling period from peak values on the day of birth. By contrast, these indices were maintained at birth levels in EGF‐treated mice for 8 days before declining to approximate those of controls at 12 and 21 days.Hair growth rate was inhibited and hair diameter reduced in EGF‐treated mice (Moore et al., 1981a). These observations were reflected in changes in the follicle bulb. Both the growth of the bulb and the increase in numbers of bulb cells observed during the early part of the anagen phase were inhibited by EGF. However, neither the size of the dermal papilla nor the numbers of papilla cells were significantly altered in treated animals. The mitotic index of the bulb cell population declined during the sampling period in both experimental and control groups. However, the labeling index of bulb cells of EGF‐treated mice was significantly increased over contemporaneous control values on days 8 and 12. Rather than stimulating epidermal growth during the early postnatal period, these observations indicate that EGF delays the normal process of skin development by maintaining the proliferative and differentiation processes active in the cell populations at the time of birth. As a consequence of this, follicle development and hair growth are inhibited.
The morphology and distribution of Merkel cells in primate gingival mucosa
Authors: Turner D. F. 
Published: February 2005

AbstractThe morphology and distribution of Merkel cells in primate gingival mucosa have been studied by correlated light and electron microscopic techniques. The gingival mucosa is composed of a stratified squamous epithelium with a dense underlying connective tissue stroma. The epithelium interdigitates with the underlying connective tissue forming long interconnected rete ridges. Merkel cells and their associated axons are abundant in gingival mucosa where they are located, either individually or in clusters, at the base of epithelial rete ridges. These cells have an identical morphology to Merkel cells described by others in the hard palate, hairy skin, glabrous skin and eyelid. While individual Merkel cells are found throughout the gingival mucosa, Merkel cell clusters are most numerous in the mandibular lingual gingival mucosa. When correlating this finding with data from other investigators, it appears that Merkel cell clusters are located preferentially in the masticatory mucosa in intimate contact with the tongue and thus may function as an important source of somatosensory feedback providing valuable information regarding the position of the tongue in the oral cavity.
The number and size of axons at the apex of the cat's canine tooth
Authors: Holland G. R. , Robinson P. P. 
Published: February 2005

AbstractUsing electron microscopy and morphometric analysis the number and size of axons entering the apex of the cat's mandibular canine tooth have been measured. The total number of axons varied from 761 to 1,903 between different animals but the maximum difference between right and left sides of the same animal was 353. From 56 to 79.6% of the axons were nonmyelinated; the difference in proportion between right and left sides never exceeded 6.4%. The mean circumference of myelinated axons ranged from 10.2 to 18.3μm but again the right and left variation was much less and never exceeded 2 μm. In one tooth 38.8% of the myelinated axons were larger than 19 μm in circumference and thus outside the Aδ range. The proportion was much smaller in other teeth but some “large” fibers were always present. Of all the nonmyelinated axons 19.7% showed some degree of axonal exposure to the extracellular space and 1.7% showed axoaxonal apposition. A small proportion of nonmyelinated axons showed evidence of apparent degeneration. Comparison of these data with those from studies at more coronal levels suggests that there is considerable branching and narrowing of fibers during their course through the dental pulp and that the degree of axonal exposure and apposition increases considerably. Some of the pulpal fibers are derived from larger axons than are normally associated with pain. The animal to animal variation in the parameters measured is considerable but right and left sides are similar.
The striated urogenital sphincter muscle in the female
Authors: Oelrich Thomas M. 
Published: February 2005

AbstractStriated muscle associated with the female urethra and vagina constitute a continuous mass which appropriately may be called the urogenital sphincter. Though continuous, the muscle may be separated into two parts—one that surrounds the urethra, and the other surrounding the urethra and vagina. The individual muscle fibers are small and are embedded in connective tissue and infiltrated with smooth muscle which obscures the visibility of the muscle to gross dissection. Developmentally the muscle primordium is laid down around the urogenital sinus and urethra early, and foreshadows the anatomical arrangement that is maintained in the adult with little change.The urogenital sphincter muscle extends from the base of the bladder where it lies within the pelvic cavity and continues through the urogenital hiatus of the pelvic diaphragm to expand around the vagina in the perineum. Additional fibers attach to the ischiopubic rami and constitute a compressor of the urethra. As a result there is no superior fascia of the so‐called “urogenital diaphragm” which closes off a deep perineal compartment or forms a floor of the urogenital hiatus.
Bilateral lesions of suprachiasmatic nuclei affect circadian rhythms in [3H]‐thymidine incorporation into deoxyribonucleic acid in mouse intestinal tract, mitotic index of corneal epithelium, and serum corticosterone
Authors: Scheving L. E. , Tsai T. H. , Powell E. W. , Pasley J. N. , Halberg F. , Dunn Jon 
Published: February 2005

AbstractInvestigations into the role of the suprachiasmatic nuclei (SCN) in the coordination of circadian rhythms have presented differing results. Several reports have shown that ablation of the suprachiasmatic nuclei (SCNA) alters the phase and amplitude of rhythms but does not abolish them. The present study investigates the effect of SCNA on the rhythms in cell proliferation in various regions of the intestinal tract as measured by the incorporation of [3H]‐thymidine into deoxyribonucleic acid, in the mitotic activity of the corneal epithelium, and in serum corticosterone levels. The study involved mice with verified lesions of the SCN (six to 13 mice per time point) and control groups of both sham‐operated and unoperated mice (seven of each per time point). The mice were killed in groups that represented seven time points over a single 24 hr span (3 hr intervals with the 0800 hr sampled both at start and end of the series). The tissues examined were the tongue, esophagus, gastric stomach, and colon for DNA synthesis, the corneal epithelium for mitotic index, and blood serum for corticosterone level. The most consistent result of SCNA was a phase advance in the rhythms in cell proliferation in the tongue, esophagus, gastric stomach, colon, and corneal epithelium. A reduction in rhythm amplitude occurred in the tongue, esophagus, and corneal epithelium; however, there was an amplitude increase for the stomach, colon, and serum corticosterone. The mesor (rhythm‐adjusted mean) was increased by SCNA in all tissues except the corneal epithelium. These findings further support the role of the suprachiasmatic nuclear area in the control of rhythms in cell proliferation and corticosterone production, by acting as a “phaseresetter” and as a modulator of rhythm amplitude.
Distribution of polyanionic sites in the developing gonads and the dorsal mesentery of the chick embryo
Authors: Didier Elaine , Didier Pierre , Fargeix Noël 
Published: February 2005

AbstractThe distribution of glycoconjugates was investigated in the embryonic trunk mesoderm used as a substrat by migrating primordial germ cells (PGCs) by means of ultrastructural cytochemistry. In both mesentery and developing gonads polyanionic sites were abundant in epithelial and mesenchymal cell coats, basal laminae, and extracellular matrices (ECM). In the latter, polyanions distributed on microfibrils and granules were associated with collagen fibers, forming an entangled network. No perferntial association of this fibrillo‐granular material with PGCs was observed, suggesting that polyanions present in ECM likely act by promoting inflation of the extracellular spaces rather than by providing mechanical guides for the moving cells.
Association of centromeric heterochromatin with the nucleolus in mouse sertoli cells
Authors: Jean Pierre , Hartung Michèle , Mirre Christian , Stahl André 
Published: February 2005

AbstractIn adult Sertoli cells of most strains of mice, all the centromeric heterochromatin is condensed in two chromocenters, one on each side of a single, large nucleolus. In a random‐bred Swiss OF‐1 strain, however, the nucleus has a different structural organization. Part of the heterochromatin is seen as chromocenters in contact with the nucleolus; the rest of it is dispersed in granules of unequal size in the nucleoplasm. Such an unusual spatial arrangement of heterochromatin in interphase nucleus cannot be explained either by a difference in the nucleolar organizing regions or by a polymorphism of the C‐banding of metaphase chromosomes.
Autoradiographic study of 3H‐methylated elastase in hamster lungs
Authors: Morris Shirley M. , Stone Phillip J. , Snider Gordon L. , Albright John T. , Franzblau Carl 
Published: February 2005

AbstractAn emphysemalike condition can be induced in animal lungs by the instillation of a single dose of elastase. Autoradiogrphy was used to determine the location of 3H‐methylated porcine pancreatic elastase in hamster lungs at four time points. Six hours after instillation of radiolabeled enzyme the distribution of silver grains was very patchy, but in heavily labeled areas grains were concentrated over macrophages, connective tissue areas and over some fibroblasts. By 24 hr the labeling of connective tissue areas was no longer evident and almost all silver grains were associated with macrophages or with the edema fluid that filled many alveoli at this time. By 4 days only macrophages exhibited concentrations of silver grains. The labeling of macrophages was still evident at 7 days.Elastase inactivated by N‐acetyl‐(L‐alanyl)3‐L‐alanine chloromethyl ketone showed a different distribution 6 hr after instillation. Silver grains were concentrated over macrophages and alveolar type II cells but showed no affinity for connective tissue areas or fibroblasts. By 24 hr almost all grains were located over heavily labeled macrophages.
Scanning electron microscopic observations of normal and regenerating nerve roots in the cat
Authors: Wakefield Caroline , Shonnard Neal 
Published: February 2005

AbstractThe surface morphology of normal and regenerated nerve roots was studied using correlated scanning and transmission electron microscopic methods. Nerve roots of the cauda equina were either cut and rejoined or crossed from a segment above to a segment below. Good regeneration was observed in both experimental procedures. The regenerated nerve root sheath had alterations in surface structure created by extensive growth of collagen. Despite this collagen formation, regenerated axons crossed the anastomotic site with relative ease. Surface features of the regenerated axons were similar in appearance to those of the normal axon. Schwann cells were easily recognized, as were the collagen fibers of the endoneurium, although the endoneurium was more prominent and occupied more of the interaxonal space. Macrophages were identified as round structures with a laminated surface or as a honeycomb structure. Internal features of the regenerating axons were more difficult to identify, but mitochondria and a fibrous network were observed. These studies have demonstrated the application of scanning electron microscopic methods to visualize surface structures and cells in regenerated nerve roots.
Quantitative analysis of zonulae occuldentes between oviductal epithelial cells at diestrous and estrous stages in the mouse: Freeze‐fracture study
Authors: Toshimori Kiyotaka , Higashi Ruiko , Ōura Chikayoshi 
Published: February 2005

AbstractThe zonulae occludentes between oviductal epithelial cells were quantitatively analyzed at diestrous and estrous stages in the mouse, using the freeze‐fracture technique. Zonulae occuldentes were predominantly anastomosing at the diestrous stage, while they were predominantly parallel at the estrous stage. The lowest mean value of junctional strands comprising the zonulae occludentes was 5.3 ± 1.6. Parallel‐type zonulae occludentes had more strands than the anastomosing type. Secretory cells usually had more strands than ciliated cells. The shallowest mean depth occupied by junctional domain was 0.51 ± 0.20 μm. The depth was usually somewhat greater in anastomosing‐type zonulae occludentes than in the parallel type. It was also slightly greater in ciliated cells than in secretory cells. The depth was likely to be greater at diestrous stage than at the estrous stage. However, neither the number of strands nor the depth was significantly different between diestrous and estrous stages in homologous types of zonulae occludentes. On the basis of these results, the zonulae occludentes in oviductal epithelium are considered to be morphologically of a tight type at any time period throughout the estrous cycle. The results of lanthanum tracer experiments suggest that the zonulae occludentes in the oviductal epithelium do not always function as a barrier to the exogenous tracer.These morphological phenomena are discussed in relation to mouse fertilization in vivo.
Mesencephalic trigeminal midline ridge formation in sharks, a proposed circumventricular organ: Developmental aspects
Authors: MacDonnell Malcolm F. 
Published: February 2005

AbstractIn scanning electron microscopic (SEM) examination of 30 shark brains, a distinctive midline ridge formation on the ventricular surface of the optic tectum was found in all juveniles and adults of the three carcharhinid species (sandbar, dusky, and smooth hound) and the one lamnid species (mako) investigated. This formation is part of the mesencephalic trigeminal (Mes V) complex of these animals, and one of its remarkable features is a population of very large cerebrospinal fluid (CSF)‐contacting and supraependymal Mes V neuronal somas. These cells, whose presence in the CSF compartment is heralded by distinct premonitory ependymal bulges, are not seen in contact with CSF until the sharks are well into their first postnatal year or later. Once established, the population of CSF‐contacting and supraependymal Mes V neurons remains in substantial numbers over the life span of the animals into the period of sexual maturity. Age‐related changes in patterns of ependymal ciliation of the midline ridge formation, tending toward a state of oligociliation, are also apparent in all species examined.Similarities between the midline ridge formation of the Mes V complex and known circumventricular organs (CVOs) are discussed and it is suggested that the formation be considered as a previously unrecognized CVO. It is hypothesized that the midline ridge formation with its contingent of CSF ‐immersed neurons, by monitoring one or more CSF factors, might serve to alter the excitability of the Mes V complex as a whole and, thus, regulate intensity of biting reflexes in sharks.
Cross‐sectional anatomy: Preparation of teaching specimens
Authors: Peppler R. D. , Kwasigroch T. E. , Hougland M. W. 
Published: February 2005

AbstractForty cross sections of a male cadaver were prepared for a Continuing Medical Education Seminar and have been used in teaching programs for the past 3 years. The sections are easy and inexpensive to construct and can be maintained with a minimal amount of effort.
In vitro transformation of chondroprogenitor cells into osteoblasts and the formation of new membrane bone
Authors: Silbermann Michael , Lewinson Dina , Gonen Hedva , Lizarbe Maria Antonia , von der Mark Klaus 
Published: February 2005

AbstractMandibular condyles of fetal mice 19 to 20 days in utero were kept in an organ culture system for up to 10 days. After 2 days in culture the cartilage of the mandibular condyle appeared to have maintained all its inherent structural characteristics, including its various cell layers: chondroprogenent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic. After 5 days in culture no chondroblasts could be seen and, instead, the entire cartilage was occupied by hypertrophic chondrocytes. At the same time, the mesenchymal cells at the chondroprogenitor zone differentiated into osteoblasts which produced osteoid. Light microscopic examinations showed that the newly formed osteoid did not stain with acidic toluidine blue or with alcian blue, but stained intensively with the van Gieson stain and with Periodic acid‐Schiff (PAS). The osteoid reacted with antibodies against type I collagen but not with antibodies against type II collagen. Electron microscopic examinations showed that the mineralization appeared to be associated with collagen fibers in bone rather than with matrix vesicles in the cartilage. The process of bone formation progressed with time and by the 10th day new bone replaced almost the entire cartilage, thus forming an expanded layer of membrane bone. This in vitro system represents an experimental model whereby undifferentiated precursor cells transform into osteoblasts with the subsequent formation of a typical membrane bone.
Development and innervation of soleplates in the freely grafted extensor digitorum longus (EDL) muscle in the rat
Authors: Hansen‐Smith Fay M. 
Published: February 2005

AbstractThe ultrastructural events in the establishment of the neuromuscular junction of the freely grafted extensor digitorum longus (EDL) muscle of the rat were studied 1–120 days after grafting. The original axons and muscle fibers, including soleplates, degenerated during the first few days, but Schwann cells and basal laminae persisted. Myofibers regenerated within the original basal laminae. Indentations of the sarcolemma, termed “presumptive synaptic clefts” (PSC), wer found on myotubes from 7‐day grafts. Schwann cells and residual acetylcholinesterase were invariably associated with the PSC, suggesting that the PSC developed at the site of the original soleplate. Nerves entered the grafts 10 days postoperatively and contacted the PSC of the regenerating muscle fibers on the 18–20th day. The secondary synaptic clefts of these “reconstructed” soleplates extended far beyond the subaxonal region. A second type of soleplate appeared on the 18–20th day. These soleplates were similar to those found in embryonic muscle and were considered to have been induced to form “de novo” by the presence of the nerves. When grafts were placed in permanently denervated limbs the “reconstructed” soleplates appeared, but the “de novo” type did not. These results shows that information directing the morphogenesis and innervation of the soleplate persists after the original muscle fibers and axons of a graft degenerate and regenerate.
Method for decreasing the statistical variance of stereological estimates
Authors: Bolender Robert P. 
Published: February 2005

AbstractThree methods are described for decreasing the statistical variance of stereological estimates. Methods 1 uses profile boundaries and surface densities of nuclear membranes, measured in thin sections, to estimate the mean diameter, surface area, and numerical density of spherical and nonspherical nuclei. For the guinea pig pancreas (number(m) = 4), the standard deviations (s.d.) as a percent of the mean for the estimates of the diameters of the exocrine, duct, and endothelial cell nuclei were 1.5%, 3.3% and 1.4%. The estimate for the mean diameter of exocrine nuclei (6.4 ± 0.1 μm) was based on a spherical model, whereas the estimates for the diameters of the nonspherical (and nonconvex) nuclei of the duct (6.4 ± 0.2 μm) and endothelial (6.7 ± 0.1 μm) cells were calculated from the numerical density of the exocrine cells and the relative frequenceis of the three cell types (determined from serial reconstructions). In an average cubic centimeter, there were 6.17 × 108 ± 0.32 × 108 (s.d. 5.1% of mean) exocrine cells, 1.64 × 108 ± 0.18 × 108 (10.9%) duct cells, and 0.803 × 108 ± 0.13 × 108 (16.6%) endothelial cells. In contrast to method 1, conventional stereological approaches were found to have standard deviations two‐to eightfold larger. Method 2 uses a mean nuclear surface area and a ratio of surface densities to estimate the surface area of a membrane compartment in an average cell. A s.d. equal to 6.5% of the mean was found for the surface are of the outer mitochondrial membrane in an average exocrine cell (672 ± 43.6 μm2), which represented an almost fourfold reduction in the s.d. compared with an earlier estimate (Bolender, 1974). Method 3 relates the surface area of a membrane compartment to a standard number of cells. Referenced to 106 cells, for example, the surface area of the inner nuclear membrane of endothelial cells had a s.d. equal to 2.9% of the mean, whereas the surface density of the same membrane compartment—referenced to a cm3 to cells—had a s.d. at 19.1% of the mean. In this case, method 3 produced almost a sevenfold reduction in the standard deviation. Similar results were found for exocrine and duct cells.The results of the study indicate that the standard deviation of a stereological estimate can be reduced to a miniumum by using a mean nuclear profile boundary to generate an estimate for a nuclear numerical density, which, in turn, can be combined with a surface density to obtain average cell information.