bluuebunny/crossref_metadata_2025 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

A 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

The 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

The 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

Using 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

Striated 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

Investigations 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

The 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

In 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

An 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

The 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

The 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

In 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

Forty 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

Mandibular 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

The 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

Three 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.
The fate of thecal smooth muscle cells in postovulatory hamster follicles
Authors: Martin Gary G. , van Steenwyk Gretchen , Miller‐Walker Cindy
Published: February 2005

Smooth muscles cells (SMC) have been identified in the theca externa of preovulatory follicles in several mammals. The function of these cells is not clear. It has been suggested that they are involved in ovulation and may play a role in the collapse of ruptured follicles and their transformation into corpora lutea (CL). In this study we used transmission electron microscopy (TEM) to examine the ultrastructure of SMC at the base of hamster follicles during the formation and regression of CL. For the first three days following ovulation, the CL are surrounded by a distinct theca externa composed of 1–3 layers of spindle‐shaped cells. The cells were identified as SMC by the masses of filaments in the cytoplasm, dense attachment plaques and caveolae along the plasma membrane and an external lamina surrounding each cell. On the fourth day after ovulation, the theca externa is fragmented and TEM observations suggest the following three fates for theca externa cells: (1) many cells degenerate, (2) some cells persist as SMC, (3) some cells possess few or no filaments and appear similar to fibroblasts. The significance of these results is discussed in regard to ovarian contractions, the fate of CL, and the recycling of ovarian tissues.
A cytochemical study of nuclear changes in fertilized hamster eggs
Authors: Da‐Yuan Chen , Longo Frank J.
Published: February 2005

Nucleoprotein changes during male and female pronuclear development have been examined in fertilized hamster eggs utilizing the ammoniacal silver reaction (ASR) at the light and ultrastructural levels of observation. Prior to its incorporation, the paternally derived chromatin was heavily laden with ASR product. Immediately upon gamete fusion the sperm nucleus underwent a dramatic increase in staining, suggesting an augmentation in the availability of reactive sites already present in the sperm nucleus or an accumulation of “new” reactive sites from the egg cytoplasm. With subsequent transformations of the sperm nucleus into a male pronucleus, there was a progressive reduction in ASR product associated with the paternal chromatin. Concomitantly, the condensed maternal chromosomes remaining in the zygote after the conclusion of meiosis dispersed and developed into a female pronucleus; these changes were accompanied by a progressive decrease in ASR staining. At the conclusion of pronuclear development, the morphologically similar male and female pronuclei were diffusely stained with the ASR. The increase in ASR staining of the sperm nucleus immediately following gamete fusion demonstrates a major effect of the egg cytoplasm on the paternal chromatin that, heretofore, has not been recognized. This augmentation and the following decrease in ASR staining may reflect changes in nucleoproteins during pronuclear development. Differences in nuclear staining are discussed in light of previous studies of nucleoprotein transitions at fertilization.
Ultrastructural evidence of continued reorganization at the aging (11–26 months) rat soleus neuromuscular junction
Authors: Cardasis Constance Ann
Published: February 2005

Ultrastructural remodeling, with evidence of focal deafferentation and reinnervation, occurs within normal young adult rat soleus neuromuscular junctions (Cardasis and Padykula, 1981). This may be related to normal variations in function. Recognition of this plasticity provides a basis for analysis of aging changes in junctional ultrastructure.

Thirty soleus junctions were studied between 11 and 26 months of life. In these junctions, compared to younger ones (3–5 months) synaptic sites with the conventional ultrastructure become increasingly sparse. There is an increase in extent and frequency of exposed junctional folds, of intervention of Schwann cell cytoplasm between axon and junctional folds, and of numbers of lysosomes in all cytoplasmic profiles. Often primary clefts are shallow or missing, and secondary folds are widened and contain collagen. Features limited largely to these older junctions include highly pleomorphic myonuclei, deeply invaginated by myofibrils, and an increase in cellular profiles between basal lamina and sarcolemma. The identity of these profiles is unknown.

At other locations within many of the same endplates, small intact terminals are associated with larger expanses of junctional folds, and several small terminals occur within the same primary cleft. Such terminals frequently contain dense‐cored vesicles. These observations suggest continuation of some terminal axonal regeneration. Thus, the ultrastructure of these aging neuromuscular junctions reveals the same degenerative and regenerative events suggested by the ultrastructure of younger junctions, but suggests a shift in the balance between them.
Structural domains of the muscle‐tendon junction. 1. The internal lamina and the connecting domain
Authors: Trotter John A. , Eberhard Susan , Samora Ann
Published: February 2005

The force generated within skeletal muscle fibers of vertebrates is transmitted to the tendon at the muscle‐tendon junction. Ultrastructural analysis of the murine muscle‐tendon junction following a variety of experimental manipulations has produced evidence that the muscle‐tendon junction can be described in terms of four principal domains (Trotter and Eberhard, 1983), two of which are discussed in the present report. Each domain is defined by the shape and orientation of its principal components, and by its position with respect to the plasma membrane. The internal lamina is composed of actin filaments, with a center to center spacing of approximately 12 nm, oriented mainly parallel to the principal vector of contractile force, and to the plasma membrane. These filaments are cross‐linked into a structural unit, perhaps by the electron‐dense structures which are associated with them. The internal lamina is morphologically connected to the external lamina (lamina densa) by a population of fine filaments oriented approximately perpendicular to the principal vector of contractile force. These filaments which constitute the connecting domain, are approximately 2–8 nm in diameter and are at least 50 nm long. They pass through three separate regions: the sarcoplasm between the internal lamina and the plasma membrane; the plasma membrane proper; and the extracellular space between the plasma membrane and the lamina densa. This third region is often referred to as the lamina lucida. These filaments are composed of at least three separate components in series, linked together by noncovalent interactions. The existence of these discrete structural domains implies that each has a different molecular composition and different mechanical properties.
The effects of beta adrenoceptor blockade with atenolol on myocardial cellular and subcellular hypertrophy in spontaneously hypertensive rats
Authors: Lauva Ines K. , Tomanek Robert J.
Published: February 2005

In this study we investigated the effects of chronic β adrenoreceptor blockade with atenolol on cellular and subcellular hypertrophy in spontaneously hypertensive rats (SHR). Atenolol was injected subcutaneously (20 mg/kg) twice daily commencing in four‐week‐old rats. The treated animals (SHR‐A) were compared to their nontreated controls and normotensive, Wistar‐Kyoto (WKY) controls at the age of 16 weeks. A group of atenolol‐treated WKY was also studied. Chronic drug treatment was effective in attenuating the rise in systolic blood pressure characteristic of SHR, but did not normalize the values to those of WKY. Cardiac hypertrophy, characteristic of SHR, was modified by drug treatment as evidenced by left ventricular weights as well as myocardial cell size. The cells from the subendocardium underwent selective hypertrophy in SHR which was attentuated by about 50% after atenolol treatment. Stereological analysis of electron micrographs showed that while relative mitochondrial volume was not affected by treatment, relative myofibrillar volume (%) decreased in both subepicardium (SHR = 63.28 ± 1.25; SHR‐A = 56.72 ± 1.37) and subendocardium (SHR = 66.53 ± 1.27; SHR‐A = 58.30 ± 1.51). This change raised the mitochondrial/myofibrillar volume ratio, which is characteristically low in SHR compared to WKY. Sarcoplasm, which included all cell constituents except mitochondria, increased with atenolol treatment, but water concentration remained unchanged. The data suggest that attenuation of hypertrophy in SHR after β blockade is associated with selective effects on the myocardial cell involving primarily the myofibrillar cell compartment.
The sensory innervation of the ovary: A horseradish peroxidase study in the rat
Authors: Burden Hubert W. , Leonard Marilyn , Smith Carlton P. , Lawrence I. E.
Published: February 2005

Injections of horseradish peroxidase (HRP) into the right or left ovary of the rat produced labeling of perikarya in both nodose ganglia and ipsilateral dorsal root ganglia (DRGs) from T10 to L2. The greatest concentration of labeled cells was in T13 and L1, DRGs. It is suggested that visceral afferent fibers from the ovary may mediate visceral reflexes that modulate ovarian function.
Ethanol inhibition of compensatory ovarian hypertrophy in unilaterally ovariectomized rats
Authors: Rudeen P. Kevin , Bo Walter J. , Krueger W. A.
Published: February 2005

The purpose of this study was to determine the effect of ethanol consumption on compensatory ovarian hypertrophy (COH) which occurs follwoing unilateral ovariectomy. Holtzman rats, 40 days old, were either unilaterally ovariectomized or sham‐ovariectomized. The rats were then placed into subgroups which would receive either an ad libitum chow and water diet, a liquid diet, or a liquid diet containing 5% ethanol. The animals were maintained on their respective diets for 11 days. The rats were killed at 51 days of age, and the ovaries and uteri were removed, weighed, and prepared for histological investigation. The results showed that uteri from ethanol‐fed animals failed to develop epithelial glands and exhibited a condensed stroma in comparison to uteri from animals fed ad libitum or pair‐fed to ethanol‐fed rats. Also, rats that were fed ad libitum had a COH of 82 ± 16% and rats that were pair‐fed a liquid diet had 114 ± 28% COH; rats that were fed the liquid diet containing ethanol did not experience compensatory ovarian hypertrophy (−3 ± 10%). Histologically, the ovaries of rats fed ad libitum showed large numbers of corpora lutea and only a few mature ova. The histology of ovaries from pair‐fed animals was similar to those from animals fed ad libitum. In contrast, the ovaries from the animals fed the ethanol diet had nearly twice as many mature ova but only one‐fourth as many corpora lutea as the number seen in ovaries from the other groups. The data show that ethanol consumption inhibits COH by suppressing ovulation and the subsequent luteal formation.
A radiographic study of variations of the human fetal spine
Authors: Bagnall K. M. , Harris P. F. , Jones P. R. M.
Published: February 2005

Variations of the vertebral column were considered to be those deviations from the norm which were still compatible with normal life and not pathological. The incidence of these variations is described as seen radiographically in a group of normal human fetuses.

Ossification centers for the costal processes of cervical vertebra 7 were found to be common (19%), being present in approximately one‐fifth of the total number of fetuses studied. They were mostly present as bilateral centers (15%), but because of the cross‐sectional nature of the study, it could not be determined whether these centers would have developed into actual cervical ribs. Far less common were the presence of lumbar ribs (1%). Ossification of the vertebral centra was found to be confusing with no clearly defined pattern being evident. In particular, there was a suggestion that some of the vertebral centra might well develop at least initially from bilateral centers. There was also evidence that the vertebral body was the product of four centers and this was supported by other literature. No variations were found which suggested that the vertebra develops from two somite levels, and this appears to be in conflict with the commonly accepted resegmentation theory.
Mesometrial smooth muscle in the mouse: Its control of uterine blood flows
Authors: Liebgott Bernard
Published: February 2005

The form and function of the mesometrial smooth muscle and the interposed mesometrial branches and tributaries of the uterine vessels were studied in the nonpregnant and pregnant mouse to see whether contractions of mesometrial muscle alter uterine blood flows. Histological sections of mouse uterine horn demonstrated that the outer longitudinal layer of myometrium extends onto the mesometrium and sandwiches the mesometrium and its vessles as a bilaminar myometrial extension (BME). The BME ends midway across the mesometrium as a free edge. Cleared specimens, perfused with silicone rubber, revealed that the mesometrial branches and tributaries of the uterine vesels formed longitudinally communicating looping arcades between adjacent mesometrial vessels. Comparisons with human dissections and uterine histological sections revealed similar patterns of mesometrial smooth muscle and mesometrial blood vessele. BME activity and its control of mesometrial blood flow were studied by transillumination of the surgically exposed mesometria of anesthetized day 12 pregnant mice. Observed contractions of the BME coincided precisely with uterine contractions measured at the cervix and the BME contractions diminished or stopped venous outflow particularly in the midhhorn regions. Arterial flows seemed to be unaffected and were diminished or halted only during infrequent forceful and sustained contractions. Trapped venous outflow passed up or down the venous arcades to escape through less restricted mesometrial veins. Uterine and BME contractions normally take place throughout gestation. It is possible that abnormally long and forceful contractions may compormise the embryo or fetus.
The structure of the parietal pleura and its relationship to pleural liquid dynamics in sheep
Authors: Albertine Kurt H. , Wiener‐Kronish Jeanine P. , Staub Norman C.
Published: February 2005

We studied the parietal pleura of six sheep to obtain information on pleura structure, blood supply, and lymphatic drainage. In the strict sense, the parietal pleura is composed of a single layer of mesothelial cells and a uniform layer of loose, irregular connective tissue (about 23 μm in width) subjacent to the mesothelial cells. The parietal pleural blood vessels are 10–15 μm from the pleural space. Tracer substances put in the pleural space are removed at specific locations. Colloidal carbon and chick red blood cells are cleared by teh parietal pleural lymphatics located over the intercostal spaces at the caudal end of the thoracic wall and over the lateral sides of the pericardial sac. In these areas the mesothelial cells have specialized openings, the stomata, that directly communicate with the underlying lymphatic lacunae. Cells and particulate matter in the pleural space are cleared only by the parietal pleural lymphatics. Compared to the visceral pleura, we believe the thinness of the parietal pleura, the closeness of its blood vessels to the pleural space, and its specialized lymphatic clearance pathways, together indicate that the parietal pleura plays a major role in pleural liquid and protein dynamics in sheep.
The postovulatory cat oviduct and uterus: Correlation of morphological features with progesterone receptor levels
Authors: Verhage Harold G. , Murray Mary K. , Boomsma Robert A. , Rehfeldt Patricia A. , Jaffe Randal C.
Published: February 2005

Oviducts and uteri were obtained from cats at estrus and up to 14 days after coitus. Progesterone binding sites were estimated by Scatchard analysis, serum levels of progesterone were determined by radioimmunoassay, and key morphological parameters of the lining of the epithelium of the oviduct and the deep uterine glands were quantitated.

Progesterone cytosol binding was hightest at estrus, significantly depleted by day 4, and continued a gradual decline out to day 14 in both tissues. Nuclear binding was markedly elevated at day 4; with time the binding decreased until by day 14 it was equal to or lower than detected at estrus. The initial depletion of cytosol binding and rise in nuclear binding coincided with the initial rise in serum progesterone levels.

Within the oviduct, the increase in nuclear binding coincided with the onsdet of regressive changes within the epithelium. These changes included atrophy, deciliation, and apotosis.

Within the uterine glands, the increase in nuclear binding coincided with the onset of the progestational response. This response included cell hypertrophy, glycogen synthesis and deposition, and with longer exposure to elevated levels of progesterone, the disappearance of these glycogen deposits.

These results clearly illustrate the immediate effect of low levels of progesterone on the subcellular compartmentalization of the progesterone receptor system, and the down regulation of the total receptor system when target tissues are exposed to a continuous elevation of serum progesterone. These result also illustrate that similar changes in receptor compartmentalization induce different morphological responses within target tissues from the same animal.
Histochemical survey of the distribution of the epidermal melanoblasts and melanocytes in the mouse during fetal and postnatal periods
Authors: Hirobe Tomohisa
Published: February 2005

In order to clarify the time of onset of the differentiation of epidermal melanoblasts and melanocytes in C57BL/10J mice, pieces of skin were excised on various days after gestation and subjected to the dopa reaction and to the combined dopa‐premelanin reaction. Cells positive to the combined dopa‐premelanin reaction (melanoblast‐melanocyte population) were first identified on prenatal day 14 in the dorsal and ventral skin, and increased in number until day 17. The population remained constant (about 140 cells/0.1 mm2 for the dorsal skin and about 65 cells/0.1 mm2 for the ventral skin) until postnatal day 4, and then decreased. However, cells positive to the dopa reaction (melanocyte population) were first indentified on prenatal day 16 in the dorsal and ventral skin, and increased until postnatal day 4 (about 95 cells/0.1 mm2 for the dorsal skin and about 25 cell/0.1 mm2 for the ventral skin), then gradually decreased and disappeared by day 30. These results indicate that mouse epidermal melanoblasts begin to differentiate on prenatal day 14, and 2 days later tyrosinase activity is induced within the cells.
Compensatory follicular hypertrophy during the ovarian cycle of the house gecko, Hemidactylus frenatus
Authors: Jones Richard E. , Summers Cliff H.
Published: February 2005

The house gecko (Hemidactylus frenatus) exhibits an ovarian cycle that can be divided into early follicular, vitellogenic, and luteal phases. Serial sections through the right ovary of animals in the three phases allowed us to quantify follicular size, condition, and number, as well as germinal bed activity. There are six to eight healthy, growing follicles in each ovary, arranged in a stepwise size hierarchy. This number does not vary among the three phases, even though one follicle becomes atretic and one ovulates during each cycle. Therefore, compensatory follicular hypertrophy occurs, leading to replacement of lost follicles and maintenance of the follicular size hierarchy.
On the maturation rate of the neutrophil
Authors: Zajicek G. , Shohat M. , Polliack A.
Published: February 2005

Fifty‐three maturing bone marrow cells of the granulocyte cell series stained with Giemsa stain and magnified 1,000 times were scanned by a “computerized microscope” consisting of a LSI‐11/23 microprocessor and a black‐and‐white video camera attached to a “frame grabber.” Each sampled cell was digitized into 70 × 70 pixels, each pixel representing 0.04 μm of the real image. The pixel gray values ranged between 0 and 255. Zero stood for white, 255 represented black, while the numbers in between stood for the various shades of gray. The cells represented six different stages of granulocytic maturation: myeloblast, promyelocyte, myelocyte, metamyelocyte, band form, and polymorphonuclear granulocyte.

A discriminant analysis program selected 19 features best distinguishing between the six different cell types and computed five canonical discriminant functions defining a Space in which maturation was studied. In the Space, distance between two cells serves as a measure of similarity. The closer two cells are, the more similar they are and vice versa. This measure was applied here to express the degree of similarity between the neutrophil maturation classes, and since they represent states in the neutrophil life history, it is applicable also as a yardstick for the quantitation of differentiation. In the Space, the life history of a cell is represented by a trajectory originating in the myeloblast and terminating in the granulocyte state. Displacement along the trajectory represents cell maturation that is expressed relatively to the least differentiated state of the myeloblast. The further a cell from this state the more mature it is. The same yardstick also serves for differentiation rate estimates represented in the Space by displacement velocities that are derived from the known “transit times” of a cell in each state. The methodology is also applied for cell production estimates.

Unlike other “computerized microscopes” serving for cell classification, the instrument described in this study is primarily a cell‐comparator providing a precise measure of similarity between any two cells.
Acetylcholinesterase and choline acetyltransferase staining of neurons in the opossum esophagus
Authors: Seelig L. L. , Doody P. , Brainard L. , Gidda J. S. , Goyal R. K.
Published: February 2005

The purpose of the present investigation was to identify and compare cholinergic intramural neurons in the lower esophageal sphincter and esophageal body by histochemical staining for acetylcholinesterase and the enzyme that synthesizes acetylcholine, choline acetyltransferase. Opossums were anesthetized and their abdominal cavity was opened by a midline incision to expose the esophagogastric junction. The lower esophageal sphincter was identified manometerically and localized in situ with markers. Tissues were removed, rapidly frozen in freon cooled with liquid nitrogen and serial cryostat sections were obtained from the lower esophageal sphincter and esophageal body. Sections were stained with one of the above histochemical procedures and adjacent sections were stained with Solachrome cyanin, which differentially stains nerve elements from muscle fibers. The muscle of the lower esophageal sphincter and esophageal body was stained with nonspecific cholinesterase with some selectivity of intensity of reaction in the various smooth muscle layers. All identifiable plexus neurons in the esophagus stained for nonspecific cholinesterase and acetylcholinesterase. Nerve fiber tracts were also stained for acetylcholinesterase within the longitudinal and circular layers of the tunica muscularis. Reaction for choline acetyltransferase showed no staining in the muscle layers or nerve fiber tracts of either part of the esophagus studied; however, selected neurons within the myenteric plexus of both regions (approximately 38%) were reactive. There was no significant difference in the number of positive choline acetyltransferase neurons in the lower esophageal sphincter or esophageal body.