bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mouse uterine glands during the delayed and induced implantation periods
Authors: Given Randall L. , Enders Allen C. 
Published: February 2005

AbstractMouse uterine glandular epithelium during the lactationally delayed implantation period and after estradiol induction of implantation was investigated using light and electron microscopy. During the delayed implantation period the lumen of this simple tubular gland is narrowed. The glandular epithelial cells have a well developed Golgi complex lateral to the nucleus, and numerous cisternae of smooth and rough endoplasmic reticula (RER) and many electron lucent apical vesicles of sizes up to 0.2 μm in diameter near the luminal border. The basal region contains lipid droplets and dispersed, irregular cisternae of RER. Twenty‐four hours after the administration of 17β‐estradiol the glandular lumina become dilated but the luminal content does not stain with azure B. Ultrastructurally the glandular cells are not remarkably different from those seen during the delay period. However, by 48 hours after estradiol administration the glandular lumina are not only dilated but filled with material which stains intensely with azure B and is ultrastructurally dense and homogeneous. The apical region of the glandular cells contains granules up to 0.4 μm in diameter composed of electron dense material similar in density to that seen in the glandular lumen. In addition, the Golgi complex has assumed a position apical to the nucleus, and the basal RER has an increased number and more orderly arrangement of cisternae.The changes seen in the uterine glands after the induction of implantation during the delay period are apparently indicative of increased secretory activity of the glandular epithelia. However, the contribution of the glands to the changes in uterine fluid composition has yet to be established.
Serous cysts of the aging guinea pig ovary. II. Scanning and transmission electron microscopy
Authors: Quattropani Steven L. 
Published: February 2005

AbstractOvarian cysts which developed spontaneously from the rete ovarii in the ovaries of guinea pigs have been examined in 1‐ and 2‐year‐old animals by scanning and transmission electron microscopy. Two cell types have been described, a tufted cell with numerous motile cilia and a non‐tufted cell with a solitary cilium. While the non‐tufted cell exhibited numerous smooth coated vesicles in its lateral and basal regions, no signs of secretion to the lumen of the cyst have been seen and occluding junctions have not been observed.
Changes in the satellite cells of growing muscle following denervation
Authors: Schultz Edward 
Published: February 2005

AbstractSatellite cells exhibit a number of distinct morphological changes after denervation which appear to be a direct response to nerve section or altered functional state of the muscle fibers. These changes appear generally related to increased movement and overall activation of the cells. After longer periods of denervation many satellite cells appear to separate from their fibers and become free cells in the interstitial space. It is proposed that this mechanism provides a cellular source for the small‐diameter, immature fibers dispersed throughout the muscle after two to three weeks. Although neo‐formation of myofibers appears to be a feature of denervated growing muscle, an increase in total fiber population was not observed. It is suggested that in the absence of a viable nerve supply the new fibers degenerate.
The freeze‐fracture study of alveolar type II cells and alveolar content in fetal rabbit lung
Authors: Kikkawa Yutaka , Manabe Toshiaki 
Published: February 2005

AbstractFreeze‐fracture replication technique was utilized to study the morphology of type II alveolar epithelial cells and alveolar contents in the late gestation of rabbit fetuses. It was shown that the lamellar inclusion bodies of type II cells were enveloped by the usual type of unit membrane with membraneassociated particles of 15 nm diameter. The interior of the inclusion bodies was composed of multiple stacks and/or whorls of membranes which were devoid of membrane‐associated particles. Small vesicles within the inclusion were found more frequently with this technique than in chemically fixed thin‐sectioned preparations.The intra‐alveolar contents were comprised of two components; spherical bodies, which were identical to the internal contents of the lamellar bodies of type II cells, and tubular elements. These tubules most often appeared rectangular on cross‐fractured faces. Triangular and hexagonal fracture faces were also noted. The tubules were seen to rest on the surfaces of the spherical components. Our observations suggest that the tubular element of the alveolar contents is formed through the interaction between the discharged lamellar body content and the alveolar fluid, and further suggest that at least the major constituent of type II cell lamellar bodies is lipid not bound to protein.Three new observations were made in this study; the absence of membraneassociated particles on the interior of the lamellae of the inclusions, the crossfractured profiles of tubular elements of the alveolar contents, and the occasional multicompartmental nature of type II cell inclusions.
The structure of the epididymis, efferent ductules and ductus deferens of the guinea pig: A light microscope study
Authors: Hoffer Anita P. , Greenberg Jon 
Published: February 2005

AbstractIn the guinea pig, the narrow part of the epididymis that traverses the upper pole of the testis and passes downward over the entire length of the gonad is composed exclusively of efferent ductules and the initial segment (zone I) of the epididymal duct. At the beginning of zone II, the narrow contour of zone I expands into a large globular region which lies adjacent to the caudal pole of the testis. The globular region of the guinea pig epididymis is commonly referred to as the cauda epididymidis but in the present study, examination with the light microscope reveals that it is composed of five histologically distinct zones (zones III through VII). A detailed histological analysis of the characteristics of the epithelium in the seven zones of the guinea pig epididymis and in the efferent ductules and ductus deferens was undertaken to obtain a better understanding of structure‐function relationships in the epididymis of the guinea pig. It was found that each of the zones could be readily distinguished on the basis of its histological features and primarily on the basis of the appearance of the principal cells.
Rat adrenocortical carcinoma 494: An integrated structural, stereological, and biochemical analysis
Authors: Moore Robert N. , Penney David P. , Averill Kathy A. 
Published: February 2005

AbstractSnell adrenocortical tumor 494 was implanted into male Sprague‐Dawley rats and recovered 7, 14, 21, 28 or 35 days following initial detection by palpation (7‐10 days following transplantation). Electron microscopic, stereologic and biochemical analyses of the tumor were compared to adrenals of normal animals to serve as a baseline for further studies of the effects of chemotherapeutic agents on tumor cells. Tumor cells possessed oval or elongated mitochondrial profiles with tubular cristae, one or two very large (> 5μ) lipid droplets, abundant ribosomes and coated vesicles, and sparse rough and smooth endoplasmic reticulum. Stereologic evaluation revealed that tumor lipid volume was 41% and mitochondrial volume 29% that of the normal adrenal controls. Tumor nuclei were 2.5 times larger than adrenocortical nuclei while cellular volumes were similar. On a net weight basis, tumor cholesterol was 55%, cholesterol ester 2.2%, and lipid phosphate 25% of respective mean values for normal adrenal glands. The tumor cholesterol: cholesterol ester ratio progressively decreased with time, but remained 18‐fold greater than the normal adrenal. Plasma corticosterone levels in tumor‐bearing rats were elevated 3‐fold by 14 days after initial detection. The adrenals of the tumor‐bearing host exhibited marked involution, the extent of which was directly related to tumor size.
Ultrastructure of the harderian gland in male albino rats
Authors: Brownscheidle Carol M. , Niewenhuis Robert J. 
Published: February 2005

AbstractHarderian glands of adult male albino rats were examined by light and transmission electron microscopy. The animals were divided into the following experimental groups: (1) castrated only, (2) castrated with testosterone replacement and (3) sham operated controls.Two types ofsecretory cells, designated as A and B, comprise the glandular epithelium and are distinguished on the basis of morphologic differences in the following cellular components:cytoplasmic secretory vacuoles, mitochondria and smooth endoplasmic reticulum (SER). Cell type A is more numerous and contains larger secretory vacuoles than cell type B which is characterized by the presence of large numbers of mitochondria and packet‐like arrangement of SER profiles. The glandular secretion appears to be elaborated via merocrine mechanisms and consists primarily of lipids and a fibrogranular substance. The latter component may consist of porphyrin compounds.Nerve endings are found in the connective tissue interstices of the gland. Direct synapses were not observed in association with either gland cells or myoepithelial cells.Castration did not produce significant alterations in the morphology of the glandular epithelium.Results of the investigation suggest that the rat Harderian gland may serve as a useful model for the study of cellular mechanisms involved in the production of human porphyrias.
The ultrastructure of the normal human thymus: A study of 36 cases
Authors: Bearman Robert M. , Levine Gerald D. , Bensch Klaus G. 
Published: February 2005

AbstractElectron microscopy of the normal human thymus demonstrates a supporting framework of epithelial‐reticular cells with long branching cytoplasmic processes joined by desmosomes. In the interstices of the epithelial‐reticular cell processes lie lymphocytes, macrophages, and rare myoid cells. Both small and large lymphocytes are evident. No desmosomes are observed between the lymphocytes and the epithelial‐reticular cells. Macrophages are most numerous in the cortex where they often contain phagocytized nuclear debris. The possible functional significance of the above‐described fine structural features is discussed.
The cingulate bridge between allocortex, isocortex and thalamus
Authors: Powell Ervin W. 
Published: February 2005

AbstractThe Fink‐Heimer silver impregnation and the autoradiographic methods were used to study the fiber projections of the cingulate cortex in the squirrel monkey. It was found that this cortex provides inputs to the striatum, thalamus and several areas of isocortex. Evidence was found for a number of fiber projections (1) Fibers from the anterior limbic area were traced to the central part of the head of the caudate nucleus, putamen, septum, dorsomedial nucleus of the thalamus, anterior hypothalamus and lateral basal nucleus of the amygdala. (2) Projections from the cingulate area were traced to the lateral part of the head of the caudate nucleus, putamen, and to the centromedian, anterior, lateral dorsal, and lateral ventral thalamic nuclei and to medial nuclei of the base of the pons. (3) There were projections from the retrosplenial area of the anterior, lateral dorsal, dorsomedial, and posterior thalamic nuclei and lateral nuclei of the pons. These results indicate that most of the cingulate gyrus is an intermediate structure between the thalamus and overlying cortex. The anterior limbic area forms a bridge between the thalamus and other areas of the cingulate gyrus and the frontal cortex. (4) The retrosplenial area and the posterior part of the cingulate area bridge the adjacent visual sensory association cortex and pelvic areas of the sensory motor cortex, respectively. These areas of the cingulate gyrus project directly to the striatum as well as to the thalamus, structurally providing limbic system input to subcortical motor structures.
Ultrastructure of the corneal nerves after fixation with potassium permanganate
Authors: Tervo Timo , Palkama Arto 
Published: February 2005

AbstractThe innervation of the rat cornea was investigated electron microscopically after KMnO4 fixation. Myelinated nerve fibres were observed only in the limbal margin of the cornea, whereas the axons located in the stroma of the avascular cornea were surrounded by the Schwann cell cytoplasm. Axon profiles with small (300‐500 A) granular vesicles and another type with agranular vesicles were seen among the non‐vesiculated fibres in all parts of the cornea. After superior cervical ganglionectomy it was not possible to find any axons with small granular vesicles. On the other hand, some degenerating axon profiles were observed in the stromal nerve trunks after ganglionectomy. In the epithelium‐naked axons with an occasional mitochondrion and a few agranular vesicles penetrated between the epithelial cells. Moreover, axons filled with several mito‐chondria were rarely observed in the epithelium, but these were difficult to differentiate from the surrounding epithelial cells.The role of the different nerve types observed in the cornea is discussed. The results suggest that the rat cornea has a dual vegetative innervation.
Fenestrations in endothelium of rat liver sinusoids revisited by freeze‐fracture
Authors: Montesano Roberto , Nicolescu Paul 
Published: February 2005

AbstractThe freeze‐fracture appearance of fenestrations of sinusoidal endothelial cells has been reassessed in perfusion‐fixed rat liver. Fenestrations, limited to the attenuated portions of the endothelial cell cytoplasm are usually round or oval in shape, with diameters ranging from 40‐600 nm. Within a given fenestrated region, they are disposed in clusters forming sieve plates. In addition, the presence of wide, irregularly shaped openings suggest that adjacent fenestrations may coalesce and result in the larger openings. Our data thus confirm the existence of both small and large fenestrae in the endothelial wall, in contradistinction to previous studies showing only regular, medium‐sized (100 nm) openings.
The morphology and kinetics of spermatogonial degeneration in normal adult rats: An analysis using a simplified classification of the germinal epithelium
Authors: Huckins C. 
Published: February 2005

AbstractThe phenomena of spermatogonial degeneration have been studied in normal adult rat testes using a simplified classification of the germinal epi‐thelium based upon the six types of differentiating spermatogonia. The following features distinguished this from schemes based on acrosome development. Rather than 14 stages of unequal duration, there are only six stages, five of which are of the same length. The classification starts at the beginning of spermatogenesis with A1 spermatogonia rather than at the onset of spermiogenesis. The classification is derived from actual biological events in spermatogenesis, namely generation times of spermatogonia, rather than upon arbitrary events in acrosome development. Most importantly, this new classification can be used with most types of preparations and in most experimental conditions.Examination of tubular whole mounts reveals that degeneration preferentially occurs in types A2 and A3 and to a lesser extent A4 spermatogonia, and is rarely seen in generations of A1 In or B cells. Deterioration is first manifested in clusters of cells joined by the intercellular bridges as they complete DNA synthesis and enter the G2 phase of cell cycle. It is characterized by a denser staining of the nuclear membrane, coalescence of chromatin into several pyknotic bodies, and eventual extrusion of the nuclear mass, leaving a cytoplasmic ghost. The sequential steps in degeneration may often be traced from one end of a synctial chain to the other, suggesting that the process may start with just one cell and then spread via intercellular bridges to involve all spermatogonia within the clone. Quantitatively, degeneration is a relatively constant feature of spermatogonial development. Only 25% of the theoretically possible number of pre‐leptotene spermatocytes are produced from the original population of A1 spermatogonia; most of this loss is incurred during the maturation of A2 and A3 generations. While the reason for spermatogonial degeneration in the normal germinal epithe‐lium remain obscure, it is proposed that the numerical ratio of A spermatogonia to Sertoli cells may be a significant limiting factor.
Observations on the development of the human atrioventricular node and bundle
Authors: Truex Raymond C. , Marino Thomas A. , Marino Deborah R. 
Published: February 2005

AbstractThis light microscopic study of the cardiac junctional tissues was based on 27 human embryos, fetuses and postnatal hearts. Evidence was presented that superficial and deep portions of the postnatal AV node were derived from two cellular primordia in the posterior wall of the common atrium at the 6‐mm stage. The small right primordia was associated with the right venous valve and gave rise to the loosely organized superficial AV node that extended posteriorly to the coronary sinus ostium. A larger left primordia formed the more compact deep subdivision of the AV node located against the anulus fibrosus. In most postnatal hearts the two subdivisions are partially or completely fused to form the adult AV node. Failure of the nodal primordia to fuse during cardiogenesis may result in two separate nodal cell aggregates above the anulus. The present observations provide a rational explanation for the two AV nodal masses described in the literature and an additional specimen that is illustrated in this communication.An AV bundle was first identified in a 13‐mm embryo and appeared to be derived from large clear cells of the posterior AV canal. At 25 mm the bundle formed a broad band across the top of the IV septum and continued into both ventricles. At this stage multiple cell strands penetrated the endocardial cushion to connect the AV bundle to the two nodal primordia. Failure of normal fusion between the AV node primordia and AV bundle can result in a variety of junctional anomalies including congenital heart block.
Immuno‐histochemical localization of cyclic nucleotides in the periodontium: Mechanically‐stressed cells in vivo
Authors: Davidovitch Zeev , Montgomery Paul C. , Yost Robert W. , Shanfeld Joseph L. 
Published: February 2005

AbstractCyclic AMP and cyclic GMP, considered to be cell proliferation regulators, have been reported to fluctuate in proliferating fibroblasts in vitro. The objectives of this experiment were to study the localization, distribution and staining patterns of these cyclic nucleotides in mechanically‐stressed, proliferating periodontal fibroblasts in vivo. Cat canines were tipped by force applications for 0 to 48 hours and serial sagittal sections of fresh frozen, unfixed, undecalcified jaws were processed immuno‐histochemically for the localization of cAMP and cGMP. Periodontal tension sites were studied microscopically. Fibroblastic staining for cAMP, which was localized mainly in the cell periphery, did not change appreciably as a result of tension. However, staining intensity increased one hour after the application of force, decreased after 6 hours and increased again at 24 hours. Staining for cGMP, initially covering the entire cell area, was concentrated over nuclei three hours after onset of tension, and diffused over cell periphery and cytoplasm thereafter. Intensity of staining for cGMP was maximal at 3 hours and low at 12 and 48 hours. These results demonstrate that stress‐induced fibroblastic responses in vivo involve alterations in staining intensity for both cyclic nucleotides which may correspond with fluctuations of these regulators, reported to occur in vitro in various stages of the mitotic cycle. Moreover, this technique enables the identification of the involved cells in a stimulated, non‐synchronized cell population.
Immuno‐histochemical localization of cyclic nucleotides in mineralized tissues: Mechanically‐stressed osteoblasts in vivo
Authors: Davidovitch Zeev , Montgomery Paul C. , Yost Robert W. , Shanfeld Joseph L. 
Published: February 2005

AbstractPrevious experiments indicate that bone cells respond to external stimuli with fluctuations of cyclic nucleotide levels. The objective of this experiment was to study the response of alveolar bone to the application of tensile forces through an examination of the osteoblastic staining pattern for cAMP and cGMP. Cat canines were tipped by 80‐g force for 0 to 48 hours. Fresh frozen, unfixed, undecalcified jaws were sectioned sagittally and stained immuno‐histochemically for cAMP and cGMP. In tension sites, osteoblastic staining intensity for cAMP decreased gradually from one to three hours, and then increased by 24 hours. Intense staining for cGMP, visible in osteoblasts of all treated cats, peaked after three hours of treatment and then again at 24 hours. Generally, groups of cGMP‐stained osteoblasts were found adjacent to unstained osteoblasts. The observed fluctuations in the osteoblasts staining pattern for cAMP and cGMP indicates involvement of these substances in the early response of osteoblasts to mechanical stimuli in vivo.
Ultrastructure of the parotid gland of the nine‐banded armadillo
Authors: Ruby John R. 
Published: February 2005

AbstractThe parotid gland of the nine‐banded armadillo (Dasypus novemcinctus) was examined by electron microscopy. In general, the ultrastructural morphology of this gland appears similar to that described in other species. The most unusual feature of the gland is that the secretory granules of the acinar cells contain a wide variety of substructures. These substructures range from a single dense core within a homogeneous matrix to a more complex cordlike network extending throughout the granule. It is suggested that this diversity of substructures is indicative of a maturation process of the secretory granules. The intercalated ducts are secretory. The myoepithelial cells are numerous, extend throughout the gland, and are associated with the striated ducts.