bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative electron microscopic study of cytoplasmic microtubules and axial unit tubules in a spermatozoon and a protozoan
Authors: Burton Paul R. 
Published: February 2005

AbstractCytoplasmic microtubules and axial unit tubules were studied in both sectioned and negatively‐stained material. Walls of microtubules of frog lung‐fluke (Haematoloechus medioplexus) spermatozoa have a helical substructure, while those of the flagellate, Trypanosoma lewisi, are composed of ten longitudinally‐oriented filaments. Cross‐bridges occur between some filaments of trypanosome microtubules. Doublet tubules of axial units in both cell types are structurally similar to the trypanosome microtubules, which may indicate similarity of function. Microtubules of fluke spermatozoa appear to be somewhat rigid, are resistant to sonication, and are considered to be mainly supportive. Circular profiles of wall subunits are seen in transverse sections of microtubules of both cell types and in doublet tubules of the trypanosome. Comparisons are made between sectioned and negatively‐stained material; while negative‐staining better reveals the fundamental substructure of microtubular elements, some distortion appears to occur. In connection with this research, a brief preliminary article demonstrated the presence of subunits in the walls of cytoplasmic microtubules of fluke spermatozoa (Burton, '66). Also, it was shown that the wall of these tubular elements possesses a helical structure, and a diagrammatic representation of the wall structure was set forth.
The morphology and function of accessory reproductive glands in the lophophores of Phoronis vancouverensis and Phoronopsis harmeri
Authors: Zimmer Russel L. 
Published: February 2005

AbstractThe enigmatic lophophoral organs of phoronids are demonstrated to by accessory sex glands. In the hermaphroditic Phoronis vancouverensis, each mature adult has two pairs of such glands: female nidamental glands that facilitate the temporary brooding of the embryos and male accessory spermatophoral organs that function in spermatophore elaboration. Functional males of Phoronopsis harmeri have complex accessory spermatophoral organs while females of this non‐brooding dioecious species lack accessory sex glands.In both species, coelomic spermatozoa are accumulated within the nephridia and passed en masse into the partially enclosed spermatophoral organs. There each sperm mass is molded into a characteristic shape and encased in one or more membranes before release as a spermatophore into the ambient water. The structure of the spermatophore is characteristic for each species and is correlated with the functional morphology of the distinctive spermatophoral organs.The existence of spermatophores, the non‐primitive nature of the spermatozoa, and additional features of reproductive biology dictate that fertilization is internal in these species, but attempts to determine the means of sperm transfer proved futile. Reproductive potential and behaviour of male Phoronopsis, means of gamete segregation in Phoronis, and general pattern of reproductive biology for both phoronids were also studied.
Proliferative response in experimentally injured frog lens epithelium: Autoradiographic evidence for movement of DNA synthesis towards the injury
Authors: Rafferty Nancy S. 
Published: February 2005

AbstractIn order to follow the movement of cells involved in the proliferative response induced by wounding, changes in the cell population of three regions of normal and injured frog lens epithelium were studied with respect to DNA synthesis and mitosis using autoradiography following intraperitoneal injection of H‐3‐thymidine. The injured lenses comprised two groups: one subjected to labeled thymidine at 40 hours post‐injury when the proliferative response begins, the other at 72 hours when the proliferative response is at its peak. Lenses were fixed at increasing intervals after injection.The data show that a central injury initiates proliferation in a large number of cells; this response appears at first mainly among the cells in the outlying proliferative (pre‐equatorial) zone, as judged by the number of labeled nuclei and mitoses seen there in the first few hours after injection in the 40 hour preparations. At later intervals labeled cells and mitoses appear centrally adjacent to the wound. And in the 72 hour preparations, the greatest concentration of reactive cells is adjacent to the wound. There is also thinning out of labeled cells in the proliferative zone and greater dilution of exposed emulsion grains over nuclei adjacent to the wound with time, suggesting that outlying cells migrate centrally, dividing en route. However, interpretation of these data is limited by the finding that H‐3‐thymidine injected intraperitoneally into the frog is not cleared rapidly from the circulation; the serum after 24 hours retains about 20% of the radioactivity (measured by scintillation counting) present at 15 minutes post‐injection.
The carotid sinus in lizards with an anatomical survey of the ventral neck region
Authors: Sidky Younan A. 
Published: February 2005

AbstractThe anatomy of the ventral neck region of the scincid lizards Chalcides ocellatus and Scincus scincus is presented and is found to be similar to that of other lizards as described in the literature. The internal carotid artery arises by 3‐5 roots from the dorsal side of the ascending limb of the carotid arch. During its first part, the internal carotid artery is completely divided into two nearly equal channels. The carotid sinus is more complicated in Chalcides than in Scincus. In lizards, it may be homologous to the carotid labyrinth of fishes and amphibians. Around the origin of the internal carotid artery are two kinds of epithelioid cells scattered in the adventitial connective tissue: a‐ large cells with rounded, faintly stained nuclei, and little, clear cytoplasm; b‐ cells with small darkly stained nuclei. Both kinds of cells appear to represent different levels of secretory activity. The number of the large cells increases with greater complexity of the carotid sinus. The cells also increase in size and number during summer (sexual period); this is especially true in younger animals. The epithelioid cells are considered to be homologous to the carotid body of higher vertebrates. The carotid sinus and epithelioid cells together form a closely interrelated system which may be intermediate between the carotid labyrinth of fishes and amphibians, and the carotid body of birds and mammals.
Sense organs on the antennal flagella of earwigs (Dermaptera) with special reference to those of Forficula auricularia
Authors: Slifer Eleanor H. 
Published: February 2005

AbstractFive types of sense organs have been found on the antennal flagellum of Forficula auricularia Linnaeus: (1) tactile hairs; (2) long, thick‐walled chemoreceptors; (3) short, thick‐walled chemoreceptors; (4) thin‐walled chemoreceptors and (5) coeloconic chemoreceptors. Earlier workers have placed the first three of these in a single class. The structural characteristics and distribution of these five kinds of sensilla on the antenna are described. All of the types except the third have been reported previously for other species but short, thick‐walled chemoreceptors have not been described before. They are remarkable for the presence of (1) a broad pad‐Like structure that absorbs dyes readily at the distal end of the peg and (2) a spheroid body, over a micron in diameter, on the dendrite of each olfactory neuron at the point where it narrows to assume the structure of a cilium. The antennal sense organs of a few specimens of Chelisoches morio (Fabricius), Labidura riparia (Pallas) and Euborellia annulipes (Lucas) were also examined.
Biomechanics of prehensile oral mucosa
Authors: Scapino Robert P. 
Published: February 2005

AbstractLarge dogs are able to deliver a powerful bite that generates considerable stress in the anterior, prehensile part of the jaws.In the upper jaw most of the biting force is borne by the anterior teeth. The palatal mucosa provides little resistance to deformation. It is easily compressed and rather mobile.In the lower jaw, the mucosa covering the upper surface of the symphysis receives a sizeable portion of the biting force. It is firmly attached to the underlying bone and possesses special connective tissue arrangements that enable it to transduce locally applied pressure to tension distributed over a broad area.
The structure of the carotid bifurcation in the lizards Tiliqua occipitalis and Trachysaurus rugosus
Authors: Rogers D. C. 
Published: February 2005

AbstractThe origin of the internal carotid artery in the lizards Tiliqua occipitalis and Trachysaurus rugosus has been shown to be both extremely variable and complex. In the dense connective tissue investing the junction of the internal carotid artery and the summit of the carotid arch are groups of cells associated with sinusoids derved from arterioles arising from the neighboring great vessels. The conspicuous epithelioid cells in these groups resemble the mammalian carotid body glomus and amphibian α cells. Nerve fibers showing no obvious synaptic specializations pass to and over these cell groups. It is suggested that these cell groups and sinusoids are comparable to mammalian carotid body glomeruli. A similar group of cells has been described in the concavity of the summit of the fourth aortic arch. This cell group, however, gives a distinct chromaffin reaction.
Three shapes of mitochondria in femoral muscle of the cockroach, Leucophaea maderae fabricius
Authors: Hagopian Martin 
Published: February 2005

AbstractThree distinct types of mitochondria as related to shape, position, and size in the femoral muscle of the cockroach, Leucophae maderae, are described. The elongated mitochondria are interposed between the myofibrils and are oriented parallel to the long axis of the fiber. Surface indentations on these mitochondria for surrounding structures indicate their permanent position. The oval mitochondria are situated under the sarcolemma. These organelles have a parallel orientation to the underlying muscle fiber but no alignment with respect to the “sarcomeric repeat” and thereby suggest that this type is mobile. The Y‐shaped mitochondria are observed in the intermyofibrillar sarcoplasm. Their paired processes are on each side of the Z‐disc and imply that the Y‐shaped mitochondria are a sessile type. The cristae in all three categories of mitochondria display a tightly packed and complex arrangement.
Oxytalan fibers in the periodontal ligament of the Caiman and the Alligator (Crocodilia, Reptilia)
Authors: Soule John D. 
Published: February 2005

AbstractHistological examination of the fibrous and cellular connective tissue components of the periodontal ligament in the Caiman and the Alligator reveals the presence of reticular fibrillae, collagenic, elastic, and oxytalan fibers, as well as fibrocytes, osteoblasts, cementoblasts and epithelial rests. The oxytalan fibers differentiated by the peracetic acid aldehyde‐fuchsin method are most numerous in the coronal region, radiating from the primary cementum into the periodontal ligament a short distance. Oxytalan fibers in fewer numbers are found interspersed between the oblique and the horizontal principal fiber bundles. Inasmuch as the crocodilian teeth have continuous replacement and thus a relatively short functional life, the oxytalan fibers of the Caiman and the Alligator appear to be proportionally fewer in number than they are in the mammalian periodontal tissues. The presence of the oxytalan fibers and epithelial rests in the Order Crocodilia (Crocodilia) adds to the number of dental structures shared with the Class Mammalia (Mammalia) (mammals) such as a stellate reticulum, a primary and secondary cementum and a periodontal ligament. This furnishes additional histological evidence for evaluation of the phylogenetic position of this group.
Histochemical patterns in the proventriculus of the developing chick
Authors: Hinsch Gertrude W. 
Published: February 2005

AbstractThe proventriculus of White Leghorn chick embryos (stages 29–45) newly‐hatched chicks, and adult chickens were frozen, sectioned in a cryostat and treated histochemically to identify localizations of alkaline and acid phosphatase, adenosine triphosphatase, 5‐nucleotidase, nucleotide‐diphosphatase, non‐specific glycerophosphatase, glucose‐6‐phosphatase, non‐specific esterase and succinic dehydrogenase. Ribonucleic acid, proteins and acid mucopolysaccharides were identified in tissues fixed in FAA.Acid phosphatase, nucleotide‐diphosphatase, adenosine triphosphatase, succinic dehydrogenase, ribonucleic acid and proteins were present in the cells of the deep glands at all stages of development. Alkaline phosphatase and 5‐nucleotidase were found only in mesenchymal derivatives of the proventriculus. After the chick begins swallowing and digesting albumen, enzymatic activity increased and non‐specific esterase became very reactive.The surface epithelium is covered with a mucous coat. Ribonucleic acid, non‐specific esterase, acid phosphatase and nucleotide‐diphosphatase were localized in the basal portions of the epithelial cells. The functional significance of these different patterns is discussed.
The histology of inhibition of limb regeneration in the newt, Triturus, by actinomycin D
Authors: Carlson Bruce M. 
Published: February 2005

AbstractAdult newts, Triturus viridescens, were treated with from 1.0–10.0 μg/g body weight of actinomycin D one day before amputation of both forelimbs. Mean survival times ranged from over 50 days in newts treated with 1.0 μg/g to 13.2 days in animals given 10.0 μg/g body weight of actinomycin. Low doses little altered the course of regeneration, but animals treated with over 2.0 μg/g never formed blastemas. In another series, animals were given doses of 2.5 μg/g body weight of actinomycin D at intervals from 14 days before to 30 days after amputation. It was found that certain signs of toxicity (loss of equilibrium) are related to the time of administration of the drug whereas others (hemorrhage into the limb stumps) are restricted to a definite phase of the regenerative process. Early administration of actinomycin completely inhibits regeneration whereas later treatment results in a considerably lessened effect. The postamputational stages which are basically destructive in nature are not noticeably affected by actinomycin D, but the phases of dedifferentiation, blastema formation and redifferentiation are strongly inhibited.
The morphogenesis of the stomach and intestine in the salamander Ambystoma maculatum
Authors: Harris Thomas M. 
Published: February 2005

AbstractThe major events associated with the morphogenesis of the amphibian alimentary tract are described and illustrated with a series of photomicrographs that present a continuous account of the differentiation process from its onset at stage 38 until the initiation of feeding at stage 46. Histological evidence is presented for the normal disappearance of the midgut region of the archenteron and the de novo formation of the intestine through the yolk mass. The mechanics of intestinal lumen formation are discussed in terms of the dynamic autonomous actions and interactions of the endoderm and the splanchnic mesoderm. The opening of the intestinal lumen as a consequence of cytolysis or cellular digestion is discounted. The relation of the present observations to the previously described polar endoderm cells is considered.
Lympho‐myeloid organs of amphibia I. Appearance during larval and adult stages of Rana catesbeiana
Authors: Cooper Edwin L. 
Published: February 2005

AbstractThe bullfrog, Rana catesbeiana, possesses lympho‐myeloid and epithelial structures that are morphologically similar in some respects to lymph nodes of mammals. These organs are present during the entire life cycle of the frog, however, the structures that are present during larval stages do not appear to be morphological precursors of adult organs. According to certain terms used previously by other investigators, two major organs are present throughout the larval stages: the lymph gland and the ventral cavity body. In the adult, the jugular body, the epithelial body, the precoracoid and propericardial bodies are found in the ventral neck region in contrast to the lateral and ventral arrangement of the lymph gland and ventral cavity body in larvae. The function of these organs is not known but it is believed that they play a role in the production of certain blood cells, particularly lymphocytes, and they may be involved in some aspects of the differentiation and maintenance of the immune response capacity.
Studies on regeneration in the creeping ctenophore, Vallicula multiformis
Authors: Freeman G. 
Published: February 2005

AbstractThe ctenophore, Vallicula multiformis (V. multiformis) (Rankin), can reproduce asexully by segregating pieces of tissue from its periphery. These pieces of tissue then differentiate to form new individuals. In 99% of the cases the pieces of tissue form normal animals; however in 1% of the cases they form “half animals” which have only one set of tentacles (the animal normally has two sets of tentacles). V. multiformis can also regenerate its apical organ, and one or both sets of tentacles.By cutting V. multiformis in half through the apical organ along the sagittal plane it is possible to produce “half animals” in 30% of the cases. “Half animals” can reproduce asexually. In 6% of the cases the new individuals which form from them differentiate as “half animals.” A part of a “half animal” that contains an apical organ will regenerate as a “half animal” while a part that does not contain an apical organ will regenerate as a normal individual. If one removes the apical organ from a “half animal,” it will regenerate it. A part of this animal containing the regenerated apical organ will regenerate as a “half animal.” If one removes the apical organ from a “half animal” and replaces it with the apical organ of a normal individual, the part containing the apical organ will regenerate as a normal individual. The results of these experiments are discussed in terms of possible mechanisms that control the process of regeneration.
Cytodifferentiation of the chick pancreas. II. Ultrastructure of the acinar cells
Authors: Przybylski Ronald J. 
Published: February 2005

AbstractThe ultrastructural changes occurring during the differentiation of the pancreatic acinar cell were studied in White Leghorn chick embryos from the onset of pancreatic morphogenesis on day 3 of incubation (day 3) to hatching. Generally, the changes included a loss of some structures, the addition of others and modification of existing structures. Numerous cytoplasmic filaments which were present in the early migrating cells of the pancreatic bud were no longer present on day 5. The nucleoli enlarged temporarily on days 5–6 and then resumed a reduced size. The Golgi apparatus enlarged by day 6 and remained this way throughout the embryonic period. Associated with these changes was the initial appearance of the zymogen granules on day 5. The endoplasmic reticulum was present initially in both the smooth and the rough forms. The rough form and the outer nuclear membrane were both initially studded intermittently with aggregates of ribosomes. Subsequently, there was an increase in the number of attached ribosomes, an increase in the amount of rough reticulum and a decrease in smooth membranes. The ribosomes attached to the membranes appeared to augment the large free ribosome population characteristic of the early cells. Mitochondria did not appear to increase in number but there was an increase in size. The granules varied in kind, number and size with developmental age. The first granules formed (days 3–5) appeared to be miniatures of the mature type. Subsequently, a heterogeneity of granule morphologies was present.
Ultrastructural differentiation of the epithelium and mucous glands of the esophagus in the chick embryo
Authors: Hinsch Gertrude W. 
Published: February 2005

AbstractEsophagi of White Leghron chick embryos, six days to hatching, were fixed in 5% glutaraldehyde in a cacodylate‐sucrose buffer, postfixed in 1% OsO4, dehydrated and embedded in Araldite. Tissues were sectioned with glass knives and viewed with a Philips EM 100C. The epithelium in early stages of development is characterized by small intercellular spaces, few cell processes and few desmosomes. In contrast the differentiated epithelium contains numerous cell processes, large intercellular spaces and numerous desmosomes. Mucin appeared in the mucous glands at 17 days.
Histology, histochemistry, and emptying mechanism of the venom glands of some elapid snakes
Authors: Rosenberg Herbert I. 
Published: February 2005

AbstractThe venom glands of several species of elapid snakes are described. The main venom gland consists of many tubules which usually contain large amounts of secretion product. The accessory gland surrounds the entire venom duct and is usually composed of uniform mucous epithelium. The epithelium lining the tubules of the accessory gland of Naja naja is composed of two distinct types of cells. Histochemical tests indicate that the main venom gland reacts with mercury bromphenol blue and PAS but not with alcian blue. The accessory gland reacts with PAS and alcian blue, and not with mercury bromphenol blue. Treatment of sections with sialidase demonstrates the presence of a sialomucin in the accessory gland. Stimulation of the muscles associated with the venom gland offers an indication of the venom expulsion mechanism of Bungarus caeruleus. A comparison of the venom apparatus of elapid and viperid snakes emphasizes marked differences in the internal anatomy of the venom glands, muscles associated with the gland, and arrangement of glandular components. The morphological differences and dissimilar venom expulsion mechanisms support the recent view of the polyphyletic origin of venomous snakes.
Cytodifferentiation of the chick pancreas. III. The content and synthesis of ribonucleic acid and proteins in developing acinar cells
Authors: Przybylski Ronald J. 
Published: February 2005

AbstractThe content and synthesis of ribonucleic acid (RNA) and protein was studied by microphotometry and autoradiography in the developing pancreatic acinar cells of White Leghorn chick embryos. These findings were correlated with previously reported changes in ultrastructural components. Shortly before or concomitant with zymogen granulation, RNA synthesis increased, in association with increases in the amount of nucleolar and cytoplasmic protein. The cytoplasmic fraction was transitory, whereas the accumulated nucleolar protein was maintained and was soon followed by an increase in nucleolar RNA. Concomitantly, a decrease in chromosomal RNA was observed, with the total amount of nuclear RNA staying constant. When zymogen first appeared, nucleoli were greatly enlarged due to large amounts of RNA and protein; total cellular RNA and protein had decreased slightly, in association with a decrease in cell volume. Subsequent development presented smaller nucleoli with decreased amounts of RNA and protein. Total cellular RNA increased due to its accumulation in the cytoplasm, probably as ribosomes. The accumulation of zymogen and the enlargement of other cellular structures contributed to an increase in total cellular protein. Prior to hatching, total cell RNA and protein decreased in amount, probably due to a reduction in cell volume through cell division.