bluuebunny/crossref_metadata_2025_split huggingface dataset:
The superior olivary complex in C57BL/6 mice
Authors: Ollo Christine , Schwartz Ilsa R. 
Published: February 2005

AbstractThe cellular and cytoarchitectural features of the lateral superior olive, the medial superior olive, the superior paraolivary nucleus and the medial, lateral and ventral nuclei of the trapezoid body are described in C57BL/6 mice using Nissl, Bodian and Golgi techniques. Principal, spindle and marginal cells are present in a well‐defined lateral superior olive. The dendrites of these cells run primarily within rostrocaudal sheets as in the cat. The principal cells of the medial nucleus of the trapezoid body are similar to the principal cells in the cat. Large multipolar cells characterize the lateral nucleus of the trapezoid body and bipolar cells with a medial‐lateral orientation are found in the medial superior olive. The largest neurons are found in the superior paraolivary nucleus and the lateral superior olive, and the medial and ventral nuclei of the trapezoid body. While brain weight and neuronal packing density change with development, the characteristic location of cell groups and the shape and Nissl‐staining pattern of neurons in the youngest brains examined were essentially unchanged in the adult mice, although dendritic maturation had occurred. The homologies of the C57BL/6 superior olivary complex nuclei with the same areas described in other mouse strains, rat and cat are discussed.This study expands our understanding of the organization of the superior olivary complex in an inbred strain of Mus musculus and relates it to other species. The data about changes occurring during postnatal maturation may aid in the interpretation of behavioral and physiological studies of neonatal plasticity of the auditory system.
Hormonal control of apoptosis in hamster uterine luminal epithelium
Authors: Sandow Bruce A. , West Neal B. , Norman Reid L. , Brenner Robert M. 
Published: February 2005

AbstractThe hamster uterine luminal epithelium undergoes cyclic morphological changes, which include mitosis and hypertrophy prior to ovulation and degenerative changes after ovulation. We have previously shown that the degenerative changes are symptoms of estradiol (E2) withdrawal; they occur within 24 hours after ovariectomy, can be prevented by E2 treatment, and are associated with a decline in the content of uterine nuclear E2 receptor (West et al., 1978).In this report, the results of an electron microscopic study of the uterine luminal epithelium in cycling and hormonally altered hamsters are described. During estrus and after ovariectomy, the death of numerous epithelial cells occurs by apoptosis. The ultrastructural alterations in such cells include condensation and margination of the chromatin, cytoplasmic condensation, amoeboid changes in cell shape with formation of pseudopodial extensions, and nuclear and cytoplasmic fragmentation. The cell fragments, or apoptotic bodies, accumulate near the basal lamina, and are then phagocytosed by macrophages, and possibly by neutrophils as well.The ultrastructural features of cell death by apoptosis in the hamster uterus are similar to those observed by others in a variety of tissues. Because of the periodic, hormonally regulated occurrence of extensive apoptosis in the hamster uterine epithelium during the estrous cycle, this system is well‐suited for further investigations on the ultrastructural alterations that occur in cells undergoing apoptosis. In addition, apoptosis appears to be a sensitive morphological endpoint of E2 withdrawal in the hamster uterine luminal epithelium.
Epidermal growth factor‐like material in rat submandibular gland
Authors: Gresik Edward W. , Van Der Noen Hendrika , Barka Tibor 
Published: February 2005

AbstractBy using an antiserum specific for mouse epidermal growth factor (EGF), only the granular convoluted tubule (GCT) cells revealed immunochemical staining in rat submandibular glands. There was no regular sexual difference in the frequency or size of immunoreactive cells. Extracts of gland contained an antigen which showed a complete cross‐reactivity with mouse EGF in radioimmunoassays. The relative amounts of EGF, determined by a heterologous radioimmunoassay, were not significantly different in the glands of rats of the two sexes. Administration of testosterone caused an increase, in both sexes, in the number of GCT cells stained for EGF and in the amount of EGF in the gland. There was no significant sexual difference in these two parameters after androgen treatment.
Electron microscopic visualization of the filamentous reticulum in whole cultured presumptive chick myoblasts
Authors: Pudney Jeffrey , Singer Robert H. 
Published: February 2005

AbstractThis present study describes an experimental approach whereby subcellular 3‐dimensional filamentous structures present within whole cells can be examined, using a conventional transmission electron microscope. This procedure uses cells which have been cultured on carbon‐coated titanium grids, and treated with Triton X‐100 to extract the soluble cytoplasm. Subsequent fixation and critical‐point drying allows filamentous proteins to be easily visualized, due to the increase in contrast produced by removal of the ground cytoplasm. The high resolution obtainable in these preparations permitted an initial classification and description of the filamentous reticulum within cultured presumptive myoblasts. This reticulum is a continuum of filaments and cables, all elements of which appear to be interconnected. These morphological findings were then correlated with the biochemical identification of detergent‐insoluble proteins, of which only actin, myosin, and, perhaps, intermediate filament and LETS protein are the major elements.
A correlated thin‐section and freeze‐fracture analysis of guinea pig adrenocortical cells
Authors: Black Virginia H. , Robbins Edith , McNamara Nancy , Huima Tellervo 
Published: February 2005

AbstractComparison of the fine structural features of guinea pig adrenocortical cells as seen in thin sections with those revealed by freeze‐fracture confirms the structural appearance of steroid‐secreting cells as interpreted from thin sections and reveals significant new features of the membranous organelles.Smooth‐surfaced endoplasmic reticulum appears as a network of tubules, interwoven or in parallel, and as cisternae, fenestrated and non‐fenestrated. These elements are tightly packed in the deeper cortical cells, excluding other organelles from their domain. Tubules and fenestrated cisternae possess randomly distributed intramembranous particles on their PF faces, while closely packed non‐fenestrated cisternae possess aggregates of particles interspersed with aparticulate regions on their PF faces. These differences in particle distribution suggest functional specialization among the various forms of reticulum.Mitochondria appear as elongated structures of varying shape. Freezefracture reveals that all their cristae have circular origins from the inner membrane. Sinuous tubules, which appear as tubules in section, and straight tubules, which appear as lamellae in section, arise from single sites. Flattened sac‐like cristae may have multiple circular origins. Definite contact points seen between inner and outer membranes may facilitate passage of molecules, including steroids, into the mitochondrial compartments.Lysosomes and peroxisomes, which are easily identified in thin sections with the aid of cytochemistry, are difficult to identify with certainty by freezefracture. Single membrane‐bound granules of slightly smaller diameter than mitochondria may represent lysosomes. Smaller granules interconnected with the tubular reticulum, as well as dilated regions of this organelle, may represent peroxisomes.Plasma membranes show no indication of tight junctions but do have abundant gap junctions which show a zonal differentiation: small gap junctions throughout the cortex, medium‐sized regularly shaped gap junctions in zona fasciculata externa, and large irregular gap junctions in zona fasciculata interna and zona reticularis. The large junctions cover planar areas as well as surfaces of projections of one cell into another. Such junctions may allow passage of ions as well as of low‐molecular‐weight substances between the cells, facilitating or even amplifying the response to trophic hormone stimulation.
The human chondrocranium at the end of the embryonic period, proper, with particular reference to the nervous system
Authors: Müller Fabiola , O'rahilly Ronan 
Published: February 2005

AbstractThe chondrocranium at stage 23 (27–32 mm C.‐R., 8 postovulatory weeks) was studied in detail to fill the descriptive gap between 7 and 9 weeks. Serial sections of ten embryos, all belonging to the same developmental stage, were investigated and compared. Graphic and Perspektomat reconstructions were made from three embryos.The chondrocranium forms a continuous mass of well‐formed cartilage, which blends with early cartilage in the nasal, orbital, and otic regions, around the future foramen rotundum, and at the site of the parietal lamina. The chondrocranium and “membrane” bones cover a relatively small portion of the brain, namely (1) the medulla and pons, (2) the caudal half of the lateral portion of the cerebellar primordium, and (3) the rostroventral part of the cerebral hemispheres. The relationships of the cranial nerves were also investigated.The degree of cranial development is intermediate between that at stage 20 (21 mm) studied by Lewis (the only other skull so far studied adequately in a staged embryo) and that of fetuses of 40 and 43 mm investigated by Macklin. On the whole, the resemblances to the fetal skulls are greater: ossification is beginning in the tectum posterius (to form the supraoccipital), and most of the “membrane” bones (except the parietal, tympanic, lacrimal, and nasal) show osseous areas. The foramen rotundum is present. The lower angle between the chordal and prechordal parts of the basal stem ranges from 129° (which resembles that at stage 20, namely 122°) to 115° (which is the same as that at 40–43 mm). An orbito‐parietal commissure is not yet present.The lower border of the larynx is at the level of the lower border of the fourth cervical vertebra. In the larynx, the thyroid laminae have usually not fused, the hyoid cartilage possesses greater and lesser cornua, the cricoid cartilage displays its signet‐ring form, and the arytenoids are identifiable as condensed mesenchyme with some early cartilage. The cartilage of the first pharyngeal arches is covered in its ventral three‐fourths by an osseous mandibular plate.Morphological variations within stage 23 are minor and appeared not to be related closely to each other, so that it was not possible to arrange the embryos in a linear developmental series based on their level of cranial morphogenesis.
Cell proliferation in follicle‐associated epithelium of mouse peyer's patch
Authors: Smith M. W. , Jarvis L. G. , King I. S. 
Published: February 2005

AbstractFollicle‐associated epithelium (FAE) from the mouse Peyer's patch consists of a dome part containing goblet as well as columnar epithelial cells and a crypt part, containing Paneth as well as goblet and undifferentiated epithelial cells. The proportions of columnar epithelial, goblet and Paneth cells in the FAE are similar to those found in normal crypt/villus complexes. Mitosis is confined to the crypts of the FAE. The cell‐renewal time for FAE columnar epithelial cells, estimated from experiments using tritiated thymidine, is approximately 60 hours. Large numbers of lymphoid cells are also present in the FAE, particularly in regions distal to the crypts. The similarity between follicle‐associated and villus epithelial structure is discussed, together with its possible relevance to “M” cell formation within the FAE.
Patterns of vascular sprouting in the postnatal development of the cerebral cortex of the rat
Authors: Rowan Reed A. , Maxwell David S. 
Published: February 2005

AbstractLight microscopic histochemistry for alkaline phosphatase was employed in a study of the development of vascular sprouting, with respect to time and distribution, in the rat cerebral cortex. Sprouts were counted in the full thickness of the cerebral cortex at each day from birth to 21 days of age. Several distinct bursts of sprouting activity were observed at specific times and levels of cortex. From birth to 4 days of age, sprouting was intense in the superficial third of the cortex. At 7 to 8 days, a burst of sprouting was found which was greatest in the middle third. Additional bursts of sprouting appeared at 10 and 14 days.Developing vessels with characteristics of arteries, capillaries, or sprouts were alkaline‐phosphatase positive, while veins were not. It is concluded that alkaline phosphatase is a useful marker for identification of both mature and immature vasculature, as it reveals patent and nonpatent vessels, and the sprouts which are precursors of the mature vascular bed. New vessels developing in the cortex arise mainly from blind sprouts of capillaries, evidently in response to the metabolic demands imposed by the maturational process.At birth, the majority of intracortical vessels are capillaries. By 10 days of age, most perforating vessels from the surface have taken on arterial or venous characteristics. The findings are discussed in connection with morphological and biochemical differentiation and the pattern of vascularization in the mature cerebral cortex.
An ultrastructural study of vascular proliferation and vascular alkaline phosphatase activity in the developing cerebral cortex of the rat
Authors: Rowan Reed A. , Maxwell David S. 
Published: February 2005

AbstractAlkaline phosphatase cytochemistry was employed to study the distribution of this enzyme in blood vessels during vascular differentiation and maturation during the postnatal development of the rat cerebral cortex. Enzyme reaction product was present in early vascular sprouts, and also throughout the subsequent maturation and differentiation of capillaries and arterial vessels. Cerebral capillaries appeared to be patent soon after the fusion of a sprout tip with another vessel; no evidence for delayed or synchronous opening was obtained. The distribution of alkaline phosphatase reaction product in vessel walls changed during vascular maturation. In vascular sprouts, reaction product was found mainly in the narrow lumen. As vessels became patent, reaction product appeared also on abluminal surfaces, at first chiefly in the narrow spaces between overlapping vascular cells. As vessels matured, reaction product became more generally distributed around the abluminal surface. In relatively mature capillaries and arterial vessels, it was restricted largely to endothelial cell surfaces and the spaces between smooth muscle cells. The significance of this distribution is unknown. Some possible explanations, including the possibility of artifact, are discussed. No alkaline phosphatase reaction product was found in differentiated veins.
Structural changes of the head components of the rat spermatid during late spermiogenesis
Authors: Lalli Michael , Clermont Y. 
Published: February 2005

AbstractThe transformation of the nucleus, acrosomic system, and perinuclear theca (perforatorium and post‐acrosomal dense lamina) was analyzed during the maturation phase, i.e., steps 14 to 19 of spermiogenesis. Following partial condensation of chromatin from steps 11–14, the nucleus continues to condense during the following steps until the end of spermiogenesis. The redundant nuclear envelope which forms along the apical and ventral aspects of the nucleus and around the implantation fossa regresses during steps 17–19. The acrosomic system splits into two portions early in step 15 to give rise to: (a) the main portion with its crest‐like acrosome running along the dorsal aspect of the nucleus and head cap extending over the lateral surfaces of the nucleus; and (b) a smaller head‐cap segment which is seen in steps 15 and 16 along one side of the nucleus at its apical extremity. This separated head‐cap segment reaches the apical‐ventral aspect of the head during step 17 and condenses in synchrony with the rest of the acrosomic system in step 19 of spermiogensis. The large crescentic acrosome, which in step 15 forms a large fin at the caudal extremity of the acrosomic apparatus, moves anteriorly during steps 16 and 17, while the whole acrosomic system extends farther apically beyond the tip of the nucleus. The perforatorium and post‐acrosomal dense lamina form a rigid capsule (perinuclear theca) that covers tightly the sickle‐shaped nucleus and binds the inner acrosomal membrane and the post‐acrosomal membranes. The post‐acrosomal dense lamina, which includes the ventral spur, appears early in step 15 as a dense cytoplasmic layer applied to the nucler envelope at the caudal extremity of the nucleus except over the perifossal zone. The perforatorium forms during step 19 of spermiogenesis as a result of the condensation of a wispy cytoplasmic material which has accumulated in the subacrosomal space during steps 14–18. Thus the spermatid's head is deeply modified during the maturation phase and takes its definitive shape only at the last step of spermiogenesis.
Fetal and neonatal rat intestinal capillaries: A TEM study of changes in the mural structure
Authors: Milici Anthony J. , Bankston Patrick W. 
Published: February 2005

AbstractThe development of intestinal mucosal capillaries was studied in Wistar rats from the fourteenth day of gestation through the second postnatal day with the transmission electron microscope. The microvessels develop first as continuous capillaries without a basal lamina and become fenestrated during later stages of gestation. In the thickened areas of the cytoplasm of endothelial cells at early stages, there is a paucity of pinocytotic vesicles; but some vesicles are observed which are larger than those in the adult. Later in gestation these larger vesicles can still be seen, but the frequency of their occurrence decreases with the maturation of the vessels. The intercellular junctions vary in length and shape, and the space between the outer leaflets of the apposed cell membranes is usually 20 nm. Surrounding the abluminal surface of the endothelium, the incipient basal lamina appears attenuated and incomplete until at least the second day of neonatal life.
The hematogenous origin of osteoclasts: Experimental evidence from osteopetrotic (microphthalmic) mice treated with spleen cells from beige mouse donors
Authors: Marks Sandy C. , Walker Donald G. 
Published: February 2005

AbstractThe excessive skeletal mass and reduced bone resorption characteristic of osteopetrosis in microphthalmic (mi) mice can be corrected by irradiation and transfer of spleen cells from a normal littermate. Osteoclasts in beige (bg) mice, a mutation without osteopetrosis, have giant lysosomal granules. These two facts were exploited to trace osteoclast lineage.Microphthalmic mice treated with whole‐body irradiation and spleen cells from a beige donor resorbed the excessive skeletal mass and recovered from osteopetrosis. Furthermore, osteoclasts in treated mi mice had giant lysosomal granules and resembled those found in bg donors when examined by light and transmission electron microscopy.These data provide direct evidence for a hematogenous origin of osteoclasts in mammals.
Pallidal projections to the mesencephalic locomotor region (MLR) in the cat
Authors: Garcia‐Rill E. , Skinner R. D. , Gilmore S. A. 
Published: February 2005

AbstractThe entopeduncular nucleus (EN) in the cat, the homologue of the primate internal globus pallidus and main output of the basal ganglia, is known to project to the mesencephalic tegmentum. We have been able to elicit antidromic responses in single EN neurons from a site in the posterior mesencephalon, then transect the brainstem (precollicular‐postmamillary) and elicit locomotion and rhythmic movements of the limbs by stimulation of the same site in the same animal. These studies demostrate the existence of a direct projection from the EN to the mesencephalic locomotor region (MLR). However, this is not a particularly large pathway since fewer than 5% of the EN cells appear to project to the MLR.In a parallel series of anatomical experiments, injections of fluorescent dyes into the area of the MLR induced retrograde labeling of cell bodies in the EN and motor cortex. Injections of tritiated amino acids into the motor cortex resulted in labeling in the area anterior to the MLR. We assume that these connections may be involved, in part, in the sequencing and ordering of series of voluntary movements in which locomotion is involved.
Osteoclast cell‐surface specializations and nuclear kinetics during egg‐laying in Japanese quail
Authors: Miller Scott C. 
Published: February 2005

AbstractMedullary bone deposits serve as a reservoir of labile calcium for egg‐shell calcification in birds. Quantitative transmission‐electron‐microscope methods and light‐microscope autoradiographic cell‐population‐kinetic analyses were used to determine changes in cell‐surface specializations and population dynamics of medullary bone osteoclasts during egg‐laying in Japanese quail. Prior to egg‐shell formation, from 0 to about 8 hours after the previous oviposition, very few osteoclast profiles had ruffled borders. The appearance of ruffled borders coincided with the beginning of egg‐shell calcification, about 9‐10 hours after the previous oviposition. During egg‐shell calcification, from about 10‐21 hours after the previous oviposition, most osteoclast profiles had ruffled borders. Ruffled borders disappeared at the completion of egg‐shell calcification and commencement of egg‐shell pigmentation. Thus, functional activities of medullary bone osteoclasts appear to be closely synchronized with egg‐shell calcification during egg‐laying.From 1 to 48 hours after a single injection of 3H‐thymidine (3H‐TdR), very few labeled osteoclast nuclei were seen during egg‐laying. Following multiple injections of 3H‐TdR, the percentage of labeled nuclei reached a peak at about 170 hours after the first injection. At this peak‐labeling time, relatively few of the osteoclast profiles that had labeled nuclei had two or more; although the average number of nuclei per osteoclast profile was about 3.6. These kinetic data suggest that the medullary bone osteoclast population has a prolonged rate of turnover compared to rapid changes in cell activities associated with each 24‐hour egg‐laying cycle; and collectively they would suggest that rapid changes in osteoclast functions occur independently of changes in cell‐population dynamics.