bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on destruction of spermatozoa in the cauda epididymidis and proximal vas deferens of non‐seasonal male mammals
Authors: Cooper T. G. , Hamilton D. W. 
Published: February 2005

AbstractThe electron microscope has been used to examine luminal spermatozoa from the cauda epididymidis and proximal vas deferens of rats, mice, hamsters and guinea pigs. Free in the lumen of all species are accumulations of a dense material within which are vesicles, granules and dense bodies, as well as spermatozoa. The spermatozoa are undergoing a process of degeneration as judged by a loss of plasma membrane from both heads and tails and further disruption of acrosomal membranes, mitochondrial sheaths and outer dense fibers. Disruption of spermatozoa also occurs outside these obvious dense masses when the luminal protein precipitated by the fixation procedure has contact with the spermatozoon. Intact spermatozoa are separated from luminal material by a clear “halo”.
Fine structure of spermatozoa of the Asiatic musk shrew, Suncus murinus
Authors: Koehler James K. 
Published: February 2005

AbstractThe fine structure of spermatozoa of the Asian musk shrew, Suncus murinus, has been investigated using air‐dried and critical‐point‐dried replicas in addition to freeze‐fractured specimens. Asymmetry in the structure of the head, notably the acrosome, can be recognized in critical‐point‐dried replicas as a slight dorsoventral convexity not apparent in air‐dried specimens. Freezeetching reveals a dense accumulation of intramembranous particles just anterior to the posterior ring, but relatively few other characteristic membrane conformations associated with the head. Gelatin smears visualized with the light microscope show a vigorous lytic response, but preliminary efforts to remove the acrosome by physiological or enzymatic incubation have thus far not been successful.
Cytological differentiation of human fetal skeletal muscle
Authors: Tomanek Robert J. , Colling‐Saltin Ann‐Sofi 
Published: February 2005

AbstractThe ultrastructural differentiation of several different muscles was investigated in human fetuses ranging in age from 13 weeks to neonatal.At approximately 16 weeks of gestation cell clusters containing both myotubes and satellite cells lie enclosed by a newly formed basal lamina and show evidence of fusion. The development of organelles is evident in myoblasts, proceeds as the cells transform into myofibers, and continues in the neonate. Filament synthesis occurs primarily in the cell periphery where thin filaments appear to align themselves in relations to parallel arrays of ribosome‐studded thick filaments; Z line formation follows the appearance of thin filaments. Intermediate filaments, approximately 10‐12 nm thick, were also consistently observed in perinuclear regions and distal to filament assembly.Although sarcoplasmic reticulum (SR) development is closely related to fibril formation, connections between Z lines and SR are not consistent, thus supporting the conclusion that SR does not evoke the formation of the Z line. Bristlecoated vesicles appear to be the precursors of elements of the SR, possibly the lateral sacs. Development of the transverse tubules, as invaginations of the sarcolemma, is closely associated with the formation of lateral sacs since the latter occur along the sarcolemma as soon as transverse tubules appear.Cytological differentiation is similar, though not identical, in several different muscles. During the last trimester muscle fibers show some evidence of diversity, mainly of variation in Z line width. In general the results suggest that the sequence and stages of human myogenesis are similar to those of other species.
Cell body locations and axonal pathways of neurons innervating muscles of mastication in the rat
Authors: Limwongse Visaka , Desantis Mark 
Published: February 2005

AbstractIn the rat the size distributions of cell bodies in the trigeminal motor nucleus and of myelinated fibers in the portio minor were bimodal. The size distribution of mesencephalic nuclear somata was unimodal. The number of fibers in the portio minor was approximated by the number of somata in the motor and mesencephalic nuclei. Within the motor nucleus large and small cells were chromatolytic after destruction of the portio minor. Injections of horseradish peroxidase (HRP) into the masseter and temporalis muscles labeled both the large and small neurons in the dorsolateral part of the nucleus. Similar injections into the anterior belly of the digastric and mylohyoid muscles labeled neurons in the ventrolateral part of the nucleus, but these neurons were not among the smallest in the nucleus. Within the mesencephalic nucleus chromatolytic somata occurred only ipsilaterally after unilateral lesions of the portio minor, and in lesser numbers after destroying the portio major. Unilateral injections of HRP into the masseter and temporalis muscles labeled cells in the ipsilateral mesencephalic nucleus and trigeminal ganglion. Labeling of mesencephalic neurons was abolished by lesions of the portio minor. Similar injections into the anterior belly of the digastric and mylohoid muscles labeled cells in the ipsilateral trigeminal ganglion, but not in the mesencephalic nucleus. These results are discussed in light of previous work on the trigeminal system.
The effect of 5‐bromodeoxyuridine on the postnatal development of the rat cerebellum: Morphologic and radioautographic studies
Authors: Yu Wan‐Hua A. 
Published: February 2005

AbstractEffects of a thymidine analog, 5‐bromodeoxyridine (BrdU), on the development of rat cerebella were studied. BrdU, when 15 milligram per 100 gram body weight was injected twice daily into 2‐day‐old rats for three consecutive days, caused a transient inhibition of cell formation and destruction of stem cells in the external granular layer. This was followed by a prolonged period of regeneration with delayed dissolution of the external granular layer; however, the restitution in cell number was incomplete and resulted in a miniature cerebellum with significantly reduced myelination at 35 days of age. The regeneration of the external granular layer appeared to alter the synchronized morphogenetic processes of the cerebellar cortex. The “desynchronization” of morphogenetic events appears to account for the peculiar cytoarchitectonic organization of the cerebellar cortex in the BrdU‐injected animals, i.e., irregular stacking of Purkinje cells, formation of granule cell ectopia, and sagittal alignment of parallel fibers in the molecular layer. It is postulated that the misalignment of parallel fibers is the consequence of BrdU substitution in place of thymine in the nuclear DNA of granule cell precursors. The present schedule of BrdU injections also appeared to reveal an additional, early period of oligodendroglial proliferative activity which did not coincide with the onset of myelination.
Development and size of the teeth of Macaca mulatta
Authors: Trotter Mildred , Hixon Barbara B. , MacDonald Barbara J. 
Published: February 2005

AbstractA cross‐sectional sample of 151 skulls from Macaca mulatta of known age and similar rearing in U.S. Primate Centers was analyzed to determine age‐related “norms” of stages of development and size of teeth.The stages of development from the follicle of a deciduous incisor in the fetus to completion of the root with apex closed of the permanent third molar were related to age. The age range observed for eruption of each tooth was noted and related to its stage of development. The crown of each erupted tooth was found to be completely developed, but growth of its root continued for a longer, indeterminate period. When a deciduous tooth was exfoliated, the crown of the permanent successor was found to be completed and root growth had begun.Measurements of both mesiodistal and faciolingual diameters and of crown length of the teeth in situ and of total length and root length on roentgenograms were examined for sexual dimorphism. The faciolingual diameter of the deciduous mandibular second incisor and of both second molars showed the greatest sexual dimorphism among both diameters of all deciduous teeth.The mesiodistal and faciolingual diameters of the mandibular premolars were found to be the best dimensions in discriminant functions for identifying sex in the absence of permanent canines.
The effects of induced lathyrism on Sr85 uptake in rats during late prenatal development
Authors: Goren A. D. , Singh I. J. , Pentel L. 
Published: February 2005

AbstractDuring the last one‐third of their gestational period, lathyritic rats incorporate significantly lower amounts of Sr85 as revealed by whole body counting techniques. This difference was maximum at term. The study provides evidence for a lathyritic disturbance in the initial phases of mineralization of hard tissue matrices.
A radioautographic study of chondrocytic proliferation in nasal septal cartilage of the newborn rat
Authors: Searles James C. 
Published: February 2005

AbstractGrowth sites within the newborn cartilaginous nasal septum have been identified by monitoring chondrocytic proliferation radioautographically. Tritiated thymidine was the labeling agent used. The results were tabulated and charted graphically; they showed the overall septum to be relatively active mitotically, yielding an average of 3.54 labeled cells per microscopic field counted. However, certain areas showed greater activity than others, namely the anterior tip (4.51 labeled cells/field), the midportion (3.98 labeled cells/field) and the posterior section of the presphenoidal tail (4.24 labeled cells/field).
A light microscopic study of the saccule and lagena in certain catfishes
Authors: Jenkins David B. 
Published: February 2005

AbstractThe sacculi and lagenae from representatives of five species of catfishes were studied by light microscopy to provide an account of the anatomy of those structures and to determine whether phylogenetic changes can be detected in the inferior division of the membranous labyrinth among closely related ostariophysian fishes. The lagena showed little change among the forms used, while the saccule exhibited marked interspecies modifications. Anatomical variation was evident in the shape of the saccule, positioning of the interconnecting transverse canal, presence or absence of a release membrane, and, more notably, the position of the saccular macula and the shape and fluting pattern of the sagitta. Only minor variations were evident in the saccule and sagitta between the “primitive” conditions displayed in the siluroid form and those in the two bagroid representatives; in the latter forms, however, some positional modification of the posterior part of the macula from the “primitive” arrangement was present. In the bagroid representatives, the general morphology appeared to be stabilized early in the radiation, and individual changes suggest two lines of development within the group. The most significant modifications were evident in the loricaroid group where progression from the early representative to the more advanced form showed major changes in the inferior division of the labyrinth including loss of the anterior part of the saccule and sagitta, modification of the remaining part of the sagitta, and repositioning of the saccular macula. The pattern changes in the saccule generally agreed with the phylogenetic sequence proposed by Chardon (′68) for catfishes.
Ultrastructure of thyroid follicular cells following hypophysial portal vascular infusion of thyrotropin‐releasing hormone
Authors: Yee John A. , Wilbur Donald L. 
Published: February 2005

AbstractUltrastructural changes in thyroid follicular cell morphology were studied following the infusion of thyrotropin‐releasing hormone (TRH) for 1 min into a hypophysial stalk portal vessel of adult male rats. At 1, 5, 15 and 30 min following infusion, thyroid glands were removed and prepared for electron microscopic examination. Thyroid follicular cells in unoperated, sham‐operated non‐infused, and saline‐infused control rats were cuboidal, generally lacked intracellular colloid droplets and contained variable numbers of electron‐dense lysosome‐like bodies distributed throughout the cytoplasm. In experimental animals, marked intracellular colloid droplet accumulation was observed 5 min after TRH infusion and remained a constant finding throughout the time‐periods studied. Numerous lysosome‐like dense bodies accumulated in the apical cytoplasm of thyroid follicular cells at 30 min. Fusion of colloid droplets and lysosome‐like bodies had apparently occurred by 30 min. At this time the colloid droplets were smaller, more electron‐dense and were often located more basally within the follicular cell cytoplasm. This study suggests that the morphological response of thyroid follicular cells to hypophysial portal vascular infusion of TRH occurs rapidly and mimics, both temporally and morphologically, the response observed following systemic administration of exogenous TSH.
Morphological changes in isolated lymphocytes during preparation for SEM: Freeze drying versus critical‐point drying
Authors: Billings‐Gagliardi Susan , Pockwinse Shirwin M. , Schneider Gary B. 
Published: February 2005

AbstractA quantitative comparison of isolated lymphocytes prepared for SEM by the critical‐point drying (CPD) and freeze drying (FD) methods revealed that the mean cellular diameter dropped from 7.9 μm after fixation to a final diameter of 6.9 μm after FD, and to 5.7 μm after CPD. In addition to their larger sizes, FD lymphocytes were immediately distinguishable by their more complex surfaces, featuring wider microvilli which often emanated from ridges on the cell surface and branched extensively near their bases. The mean width of microvilli was 0.22 μm after FD and 0.12 μm after CPD. The number of microvilli per cell was essentially the same by the two methods. In view of these findings, a critical comparison of the CPD and FD methods using the particular cells or tissue to be investigated is an essential prelude to a rigorous SEM study.
Phagocytosis of photoreceptor outer segments during retinal development in utero
Authors: Spira Arthur W. , Huang Peter T. 
Published: February 2005

AbstractThe retinal pigmented epithelium of the fetal guinea pig was examined for evidence of phagocytosis and degradation of outer segments. Beginning at the early stages of outer segment formation and continuing through the remaining fetal period, pigment epithelial cells contained large and small phagosomes with multi‐lamellated internal structure. Thus, mammalian retinal photoreceptor cells which normally develop and mature in utero in the absence of light undergo a process of phagocytosis of outer segment fragments comparable to that found in species whose retinae mature postnatally outside of the uterus.
Specific subclones derived from a multipotential clone of rat anterior pituitary cells
Authors: Shiino Masataka , Ishikawa Hiroshi , Rennels Edward G. 
Published: February 2005

AbstractSeveral functional subclones of rat anterior pituitary cells were established from our 2A8 clone which apparently contains a heterogeneous population of committed and uncommitted cells. On the basis of the hormones secreted into the culture media, as measured by radioimmunoassay, these subclones were divided into four categories, i.e., subclones which secrete (1) ACTH only, (2) prolactin only, (3) prolactin and GH or (4) ACTH, prolactin and GH. None of the subclones produced detectable amounts of thyrotrophic or gonadotrophic hormones. Subclones which secrete a single hormone have shown no change in the type of hormone produced, indicating that these subclones were each derived from a committed cell.The cells of all subclones exhibit a normal diploid karyotype and show good growth characteristics. The cells of the different subclones can be classified by phase contrast microscopy into four categories. However, no clear‐cut ultrastructural features have been observed which can be correlated with the different categories of subclones. On the basis of the results a hypothesis is proposed relative to the functional cytodifferentiation of anterior pituitary cells.
Occurrence of catecholamine‐containing specific granules in the venous endothelia of carp
Authors: Iijima Tadahiko , Wasano Takeo 
Published: February 2005

AbstractThe formaldehyde‐induced fluorescence technique and the argentaffin reaction with ultra‐thin sections were applied to the vessels of carp to demonstrate the presence of a catecholamine. After formaldehyde gas treatment for 30 minutes at 50°C, the venous endothelia emitted a greenish‐yellow fluorescence suggesting the presence of a primary catecholamine. In the endothelial cells of veins, the specific granules, consisting predominantly of spherical granules with a diameter of about 0.3 μm, showed heavily to moderately positive argentaffin reaction. Granules also occurred in the endothelial cells of arteries. However, these granules stained weakly or not at all with ammoniacal silver solution. It is concluded that the specific endothelial granules in veins of carp contain a primary catecholamine.
The atrioventricular node and bundle in the ferret heart: A light and quantitative electron microscopic study
Authors: Marino Thomas A. 
Published: February 2005

AbstractThe cells of the atrioventricular (AV) junction in the ferret heart were examined using light microscopy, a wax‐model reconstruction and quantitative electron microscopy to determine their organization and characteristics. A series of subdivisions of the specialized tissues of the AV junction was apparent at both the light and electron microscopic levels. A transitional zone was observed interposed between the atrial muscle cells and the AV node. The AV node consisted of a coronary sinus portion, a superficial portion and a deep portion. The AV bundle had a segment above the anulus fibrosus, a segment which penetrated the right fibrous trigone, a non‐branching segment below the anulus fibrosus and a branched segment. At the ultrastructural level the AV junctional conduction tissues had fewer irregularly oriented myofibrils than did working atrial myocardial cells. T‐tubules, present in atrial muscle cells, were not observed in the modified muscle cells of the AV node and bundle. Conventional intercalated discs also were not observed between the cells of the AV node or the AV bundle.Atrial myocardial cells had the highest percentage of the plasma membrane occupied by desmosomes, fasciae adherentes and gap junctions. The AV bundle cells had the highest percentage of appositional surface membrane and a relatively large fraction of plasma membrane occupied by gap junctions. Cells of the superficial portion of the AV node had the smallest percentage of the plasma membrane composed of gap junctions, desmosomes or fasciae adherentes, as well as the smallest fraction of the cell membrane apposed to adjacent cells. The stereological data indicate that the most useful distinguishing characteristic between atrial muscle cells and conduction cells was that a smaller percentage of the conduction cell sarcoplasm was occupied by mitochondria and myofibrils. The most useful characteristics that could be used to differentiate between the regions of the AV junctional conduction tissues were the amounts and types of surface membrane specializations in the respective cell types.
Three‐dimensional architecture of the Golgi apparatus in Sertoli cells of the rat
Authors: Rambourg A. , Clermont Y. , Hermo L. 
Published: February 2005

AbstractGlutaraldehyde‐fixed testes were stained “en bloc” with the Ur‐Pb‐Cu technique of Thiéry and Rambourg ('76) or post‐fixed and stained with the osmium tetroxide‐potassium ferrocyanide method of Karnovsky ('71). Thin or thick (up to 3 μm) sections were examined with the Philips (301 or 400) EM or the high voltage EM. Stereopairs were prepared with photographs of tilted specimens (± 7°).At low magnification, in thick sections (0.5–3 μm) stained with Ur‐Pb‐Cu, the whole Golgi apparatus formed a single network of interconnected wavy ribbon or platelike structures extending from the juxtanuclear region toward the apex of the cell. At higher magnifications, with the two staining techniques, this Golgi network showed two distinct types of regions: the “saccular region” corresponding to the conventional stack of saccules and the “intersaccular connecting region” made up of anastomotic tubules which bridge adjacent stacks. In the saccular regions, there was, on the cis‐face of the stack, a tight polygonal meshwork of anastomotic tubules (osmiophilic element). Underlying it there were three to seven closely apposed saccules perforated with pores of various diameters, and finally, on the trans‐face, a network of tubules was usually connected to the last saccule of the stack, which seemed to peel off from the pile,The intersaccular connecting regions showed proximal and distal zones with regard to the associated stacks. The proximal zone was made up of superimposed and parallel polygonal networks of membranous tubules which were continuous with corresponding saccules of the stack. In the distal zone they interdigitated, intertwined, anastomosed and bridged adjacent saccular regions; others turned at right angles and established connections with tubular extensions arising at various levels of the same stack. While cisternae of endoplasmic reticulum were contiguous with tubules or saccules located on the transface of the Golgi apparatus, a close association between the ER cisternae and the cis‐face of the stacks was not usually observed.
A morphometric study quantifying the mucus content of proliferating colonic epithelial cells
Authors: Porcella Russell A. , Swartzendruber Donald C. , Godbold James H. 
Published: February 2005

AbstractWe report a quantification of the maximum mucus accumulation in proliferating rat colonic epithelial cells. The proliferative potential was determined by radioautographic study of one‐hour pulse exposures to tritiated thymidine, mucous content was determined by Periodic‐acid Schiff (PAS) staining. We examined 55 labeled mucous cells in 0.5‐ to 1‐μm serial sections. The maximum thecal and nuclear profiles of these cells were photographed and their surface areas were determined utilizing a coordinate sensor. The data were expressed as a theca‐to‐nucleus (T/N) ratio. The maximum (T/N) ratio for a labeled mucous cell was 3.0. We performed a similar analysis on 22 unlabeled mucous cells from upper crypt regions and surface epithelium to derive the range of (T/N) ratios for terminally differentiated mature mucous cells. The range of (T/N) ratios from these cells was from 4.8 to 16.4. Our study shows that proliferative potential of mucous cells is determined by the interrelationship between mucus accumulation and nuclear size.