bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitation of ultrastructural changes in the mouse pineal in response to continuous illumination
Authors: Upson Rosalyn H. , Benson Bryant , Satterfield Virginia 
Published: February 2005

AbstractAdult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but non‐significant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross‐sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment.These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.
Alterations in the fine structure of the prostate and seminal vesicle of rats treated with cyproterone acetate
Authors: Loving Charles K. , Flickinger C. J. 
Published: February 2005

AbstractYoung adult male rats were treated with daily injections of 10 mg of cyproterone acetate for periods up to 16 weeks. Samples of the ventral prostate and the seminal vesicle were studied with the light and electron microscopes. Alterations visible with the light microscope included decreases in cell size, cytoplasmic basophila, the size of the nucleolus, and the amount of luminal secretory material. Ultrastructural changes in the epithelium of both glands involved mainly the organelles that participate in the formation of secretions. Large declines were observed in the abundance of rough endoplasmic reticulum, size of the Golgi apparatus, and number of secretory vacuoles. Lipid droplets accumulated in the seminal vesicle epithelium, and lysosomes were numerous in both glands. Changes were first observed microscopically in the seminal vesicle after one week and in the prostate after two or three weeks. Maximal development of the alterations occurred after treatment for approximately eight weeks.
Cell associations and surface features in cultures of juvenile rat seminiferous tubules
Authors: Eddy E. M. , Kahri A. I. 
Published: February 2005

AbstractShort pieces of seminiferous tubules from juvenile rats were grown in tissue culture and studied by phase contrast light microscopy while living and by transmission and scanning electron microscopy after fixation and appropriate processing. The pieces of tubules remodeled in vitro, with the original explant becoming surrounded closely by a sheet of epithelioid cells and more peripherally by elongate cells. The epithelioid cells were identifiable as Sertoli cells because of the presence of characteristic Sertoli‐Sertoli cell junctions near their upper surface. The elongate cells were derived from peritubular tissues, but could not be specifically identified as to cell type. Clusters of stellate cells and of round cells were present on the upper surface of the Sertoli cell sheets, but not on the elongate cells or the bare floor of the culture dish. The stellate cells were spermatogonia and the round cells were spermatocytes, as identified by fine structural features. Intercellular bridges were maintained between germ cells in culture without being surrounded by processes of Sertoli cells. Rudimentary junctions were present between germ cells and Sertoli cells in culture. The shape of germ cells in vitro was the same as the shape in situ, indicating that shape is an inherent feature of germ cells and is not determined by surrounding Sertoli cells.
The development of the lung in the pig‐tail monkey (Macaca nemestrina,L.)
Authors: Boyden Edward A. 
Published: February 2005

AbstractThis study covers the period from the fortieth day after ovulation to the thirty‐eighth day after birth. In addition, lungs of two mature monkeys have been analyzed. Birth occurs about the one hundred sixty‐eighth day (24 weeks after ovulation). By the fortieth day the patterns of the bronchopulmonary segments are well established. These are the tools of the investigator. The curve of growth for the first 60 days parallels that of the rhesus monkey but is steeper than the human curve. At 63 days (9 weeks) pairs of rosette‐like clusters of epithelial buds (future alveolar ducts) have appeared on peripheral branches of the segmental bronchi and continue to grow in size until the twelfth week. Then they resemble the paired rosettes of human acini of the seventeenth postovulatory week (Boyden, ′74) and probably represent the primitive unit from which the human was derived. In both man and monkey, canalization of the rosettes starts at about the same relative time (the 17th and 12th week, respectively) and spreads centralwards from the rosettes along the bronchioles of each segmental bronchus. In man, canalization forms acini (alveolar ducts and respiratory bronchioles). In the monkey, due to the monopodial pattern of branching, it produces racemes of alveolar ducts, each raceme ending basally in a pseudorespiratory bronchiole (127th day). By the one hundred fortieth day, enough surfactant has been secreted to support a premature infant. At one hundred fifty days, 11 generations of bronchi, followed by 16 of pseudorespiratory bronchioles, are present in the medial basal segment, followed in turn by 19 generations of prealveolar ducts (the latter provided with delicate spiral muscles) each giving off alternate branches of alveolar ducts. After one hundred fifty days of gestation, generations of bronchi, pseudorespiratory bronchioles, prealveolar ducts and cartilages (15) remain virtually constant for at least 38 days after birth. By the adult stage the number of generations of pseudorespiratory bronchioles has been reduced to three and the prealveolar ducts increased (at the former's expense) to 27. This study is concluded with a comparison of the lungs of the newborn monkey with those of the human/neonate and puppy.
The Sertoli cell junctional specialization during spermiogenesis and at spermiation
Authors: Ross Michael H. 
Published: February 2005

AbstractThe relationship between developing spermatids and Sertoli cell junctional specializations was studied with the electron microscope during spermiogenesis and at spermiation. At stage I of the seminiferous cycle, the newly formed spermatids are found in apposition to junctional specializations at the lateral surfaces of the Sertoli cell. Visualization of the junctional site of this early stage appears to be dependent on orientation and plane of section. As differentiation proceeds, the spermatids elongate and come to lie within deep recesses of the Sertoli cell. At this time the junctional specialization is limited to the acrosomal portion of the spermatid. During the maturation phase, the spermatids, while maintaining the same relationship to the junctional specialization, approach the lumen. When stage VIII of the cycle is reached, the stage in which spermiation occurs, the spermatids are at the luminal surface. The relationship of the spermatid head to the junctional specializations is quite variable during this stage. Some spermatids are observed still attached to the Sertoli cell at the junctional site, while others are found completely or partially surrounded by Sertoli cytoplasm, but with no evidence of the normally interposed junctional specialization. Yet, in other instances, the spermatids are observed in a position slightly removed from the junctional site. Also evident are profiles of junctional specializations at a free surface of the Sertoli cell, there being no attached spermatid. In some instances the junctional specializations appeared in apposition to a residual body. In the case of the free surface profiles, the junctional specialization at times lined an empty cleft or crypt‐like recess, giving the impression that the spermatid head had just been dislodged from the junctional contact site. The findings indicate that the spermatid is in contact with a junctional specialization from its initial appearance and remains so until spermiation is initiated. It is postulated that spermiation is initiated through a physiological change in the junctional specialization resulting in loss of adhesion and consequent release of the sperm head from its attachment site. A similar mechanism is proposed in relation to the inter‐Sertoli junctional complex to account for the means by which the spermatocytes cross this barrier to reach the adluminal compartment of the seminiferous epithelium.
The ligaments of the human wrist and their functional significance
Authors: Mayfield J. K. , Johnson R. P. , Kilcoyne R. F. 
Published: February 2005

AbstractThe ligamentous anatomy of the wrist was analyzed by studying (1) 28 dissected human wrists, (2) and by examination of 19 wrist injuries created mechanically. Six volar intracapsular ligaments are described, two stabilizing the distal carpal row, three stabilizing the proximal carpal row and one stabilizing the proximal scaphoid pole. More specific terminology for these ligaments is proposed. An explanation of how these ligaments participate in the mechanical functioning of the carpus is advanced. Mechanically created wrist injuries had ruptures of specific ligaments as described augmenting a need for a more specific terminology. Suspected mechanisms of injury in perilunate and lunate dislocations are mentioned based upon the functional understanding of the intracapsular ligaments.
The subdural neurothelium of the cranial meninges in man
Authors: Rascol Madeleine M. , Izard Jacques Y. 
Published: February 2005

AbstractThe neurothelium obtained from human biopsy specimens is a very thin cellular layer located between the dura mater and the arachnoidea. It is a pluri‐stratified squamous layer which has some epithelial features (desmosomes and tonofilaments), and lacks connective tissue fibers in the extracellular spaces. Usually there is increased nuclear and cytoplasmic density and enlarged extracellular spaces from the deepest to the most superficial layer.Since neurothelium is fragile and easily torn apart, it probably occupies the position considered to be the subdural space.
The accessory optic fiber system of the golden hamster with special reference to retinohypothalamic projection
Authors: Lin Homin , Alexander Mary , Giolli Roland A. 
Published: February 2005

AbstractThe hamster accessory optic fiber system has been investigated with the use of de Olmos‐Ingram and Fink‐Heimer silver methods following the production of unilateral ocular enucleation. It was found that this fiber system consists of both crossed and uncrossed inferior and superior fasciculi. The fibers of the inferior fasciculus (anterior accessory optic tract) run along the medial edge of the cerebral peduncle and terminate within the medial terminal nucleus of the accessory optic system. The fibers of the superior fasciculus (posterior accessory optic tract) leave the main optic tract, pass superficially over the medial geniculate nucleus and the cerebral peduncle; they synapse within the dorsal, the lateral and the medial terminal accessory optic nuclei. The presence of a retinohypothalamic tract could not be confirmed.
The nuclear fibrous lamina in human cells: Studies on its appearance and distribution
Authors: Cohen Arthur H. , Sundeen James R. 
Published: February 2005

AbstractThe nuclear fibrous lamina, a structure of unknown function, is situated at the nuclear periphery directly apposed to the inner nuclear membrane. Although it has been well described in invertebrate and many non‐human vertebrate cells, its occurrence in human tissue has not been emphasized. This survey of a large variety of human cells has documented the lamina to be present, although of varying thickness, in a large number of cell types. It is consistently thickest in mesenchymal or mesenchymally derived cells and its apperance and thickness is not correlated with pathologic alterations.
The mammalian rete testis — a morphological examination
Authors: Dym Martin 
Published: February 2005

AbstractThe fine structure of the rete testis was examined in several primates, domestic animals and rodents. The rete testis consists of a series of interconnected wide channels lined with a simple cuboidal to columnar epithelium, resting on a thick basal lamina. Beneath the basal lamina dense bundles of collagen fibrils and a few blood vessels, lymphatics or nerve tissue are found. The epithelial cells are characterized by large, deeply indented nuclei, spherical or short rod‐shaped mitochondria, supranuclear Golgi profiles, some cisterns of rough endoplasmic reticulum, free ribosomes and numerous micropinocytotic vesicles in the ectoplasmic regions. Smooth endoplasmic reticulum, secretory granules, lysosomes or other types of dense bodies are rarely seen. The apical surface of the cells bears numerous microvilli and a single very long flagellum which is presumed to be motile. Adjoining lateral cell membranes exhibit a juxtaluminal tight junction, elaborate interdigitations and desmosomes. The basal plasma membrane is highly irregular greatly increasing its surface area of contact with the underlying interstitium. The nuclei of the rete epithelial cells contain pale‐staining, spherical structures, 2 m̈ in diameter, composed of circularly oriented fine filaments. The significance of the nuclear structures remains unknown. Thorotrast was injected into the lumen of the hamster and rat rete testis and 30 minutes later the proximal portion of the excurrent duct system of the testis was prepared for electron microscopy. Whereas the ductuli efferentes and first part of the epididymis possessed numerous apical vesicles filled with the thorotrast, this electron opaque substance was rarely found in the epithelium of the rete testis. Thus, incorporation of particulate matter into the lining cells of the rete from its lumen is apparently less active than in the epithelium of the ductuli and epididymis. Vascularly introduced intercellular tracer compounds such as lanthanum nitrate or horseradish peroxidase did not enter the lumen of the rete testis from the interstitium. These tracer molecules appeared to be blocked by the juxtaluminal tight junction separating adjacent epithelial cells. This latter observation suggests that a blood‐testis barrier exists at the level of the rete testis epithelium. Although physiological studies have indicated that the composition of fluid secreted in the seminiferous epithelium is considerably modified in the rete testis, the present morphological study does not provide additional evidence to support a secretory or absorptive function for this region of the excurrent duct system of the testis.
Ultrastructural distinction between reticular and collagenous fibers with an ammoniacal silver stain
Authors: Snodgrass Michael J. 
Published: February 2005

AbstractReticular and collagenous fibers stain differently when subjected to ammoniacal silver reduction. A variety of tissues were subjected to such a “reticulin” technique and the association of reaction product with intercellular connective tissue elements was studied with the electron microscope. The reaction with reticular fibers was primarily associated with the interfibrillar matrix, and was globular in form having a wide variety of particle sizes. Conversely, in dermal collagen the unit fibrils were stained rather than the interfibrillar matrix. The precipitate was punctate in form and was associated with the cross striations of unit collagen fibrils. Large microfibrils also reacted positively with the stain, imparting a faint periodicity. Basement membranes were stained uniquely. The underlying plasmalemma and the lamina densa were heavily stained with silver while the lamina lucida was relatively unstained. The unit fibrils of the lamina reticularis stained in the same manner as dermal unit collagen while the ground substance remained unstained. This represents a clear distinction between the argentophilic characteristics of collagenous fibers, reticular fibers, and basement membranes.
Degeneration of germ cells in normal, hypophysectomized and hormone treated hypophysectomized rats
Authors: Russell Lonnie D. , Clermont Yves 
Published: February 2005

AbstractIn normal adult rats some germ cells degenerate at several vulnerable steps of spermatogenesis. These are the type A spermatogonia, midpachytene spermatocytes, primary and secondary spermatocytes which degenerate during their respective maturation divisions and step 7 and 19 spermatids. In the present study, these degenerating cells were examined under the electron microscope, and their frequency was determined in toluidine blue stained semithin sections of testes from normal, hypophysectomized (at 5.5 days after operation) and hypophysectomized rats injected with FSH and LH separately or in combination. With the exception of the step 19 spermatids, the degenerating germ cells underwent necrosis in vacuolated spaces delimited by Sertoli cells. In the case of the affected step 19 spermatids, an apical cytoplasmic process of the Sertoli cell initially ensheathed a long segment of their flagellum, and then each degenerating cell was drawn deep in the seminiferous epithelium where it was phagocytozed by the Sertoli cell. Soon after hypophysectomy the incidence of degenerating mid‐pachytene spermatocytes, step 7 and 19 spermatids which are present in stages VII or VIII of the cycle of the seminiferous epithelium, increased significantly. In contrast the number of degenerating primary or secondary spermatocytes during the meiotic divisions seen in stage XIV of the cycle or of any other germinal cell was not significantly modified. While the injection of FSH alone had no influence on the number of degenerating cells in hypophysectomized rats, injections of LH at the two doses administered (0.7 μg or 20 μg) reduced significantly the number of degenerating cells seen in stages VII‐VIII of the cycle; combined injections of FSH and LH (20 μg) reduced the number of these degenerating cells to the normal low values. Thus it appeared that the mid‐pachytene spermatocytes and the step 7 and 19 spermatids, all present in the adluminal compartment of the seminiferous epithelium in stages VII or VIII of the cycle, were more sensitive to the presence of absence of gonadotropic hormones than the other germ cells present in the seminiferous epithelium.
Electron microscopic studies on the myotomes of larval lamprey, Lampetra japonica
Authors: Nakao Taisuke 
Published: February 2005

AbstractMyotomes of the caudal one‐third of the body of 26‐day‐old larval lampreys, Lampetra japonica, were studied by electron microscopy. Each myotome consists of horizontally stacked muscle lamellae. The myotomes are covered laterally by a single layer of flattened cells called here “lateral cells,” and the other aspect is covered by an external lamina. The myotomes are mid‐segmentally innervated.Each muscle lamella usually contains two single cortical layers of myofibrils along the dorsal and ventral sarcolemma with a nucleus and mitochondria interposed between two layers. Numerous peripheral couplings are observed with relatively less developed triads. There are no membrane specializations to connect adjacent muscle lamellae within a myotome. Intermyotomal junctions are, however, noted between tips of cytoplasmic processes of muscle lamellae of adjoining myotomes. They resemble tight or gap junctions. No myofibrils are present in these cytoplasmic processes. Myotendinous junctions, with “terminal couplings” (Nakao, 1975), are seen under development at the myoseptal ends of muscle lamellae.Lateral cells contain only ordinary organelles and no special structures such as myofibrils are found in the cytoplasm. They are connected to each other and to muscle lamellae by primitive desmosomes. They generally have no external lamina investment.
Development of meissner corpuscle of mouse toe pad
Authors: Idé Chizuka 
Published: February 2005

AbstractThe cytologic development of Meissner corpuscles of the mouse toe pad has been studied using light and electron microscopy, and correlated with silver impregnations of frozen sections. By 18 days of gestation, neurites are seen near the epidermis, but intraepidermal neurites are few. One day after birth, the number of intraepidermal neurites increases, and some accompanying Schwann cells extend their cytoplasmic processes penetrating the basal lamina of the epidermis. Four days after birth, Schwann cells invade the epidermis further, extending many cytoplasmic processes which are intimately associated with basal cells of epidermis. These specialized Schwann cells which contact the epidermis proper also begin to develop cytoplasmic lamellae and thus denote the onset of lamellar cell development. By eight days after birth, the developing lamellar cells become more elaborated, and their cytoplasmic processes contain caveolae and filaments, characteristic features of lamellar cells. This developmental sequence supports the concept that lamellar cells are derived from Schwann cells. Through all stages of development, neurites and Schwann cells interact closely with epidermal cells. Epidermal cells may be essential for corpuscle formation. By 20 to 25 days after birth, mouse toe pad Meissner corpuscles are cytologically mature.
Location of progenitor cells in periodontal ligament of mouse molar stimulated by wounding
Authors: Gould T. R. L. , Melcher A. H. , Brunette D. M. 
Published: February 2005

AbstractWounds were made in the alveolar process overlying the mesial root of the mandibular first molar of 35‐g mice to expose periodontal ligament. Dividing cells were arrested in metaphase by injection of vinblastine sulphate three hours before death three, five and seven days after wounding. Serial 1‐m̈m plastic sections of the wound were stained with hematoxylin and eosin. The distance between the mitotic figures and the nearest blood vessel, bone and cementum was measured in every fourth section. No mitotic figure was measured twice. The distances of at least 500 interphase cells from the closest blood vessel were measured in each wound. At all time periods the distribution of mitotic cells was significantly closer to blood vessels than that of interphase cells (p < 0.01). From three days to seven days after wounding there was a significant shift of mitotic activity away from the bone side of the ligament, but not away from blood vessels (p < 0.05). Approximately 10% of all mitotic cells lay close to cementum, but not close to blood vessels. The majority of the dividing cells were confirmed to be paravascular, and appeared to belong to two populations, one adjacent to bone, the other in the body of the ligament. A third population, not paravascular, lay adjacent to cementum.