bluuebunny/crossref_metadata_2025 huggingface dataset:
Reimagining Teacher Preparation: Digital Literacy in the Post-Pandemic Era
Authors: Wang Yu-Mei , Harmer Peter A.
Published: February 2024

The advent of COVID-19 exposed significant flaws in the capacity of educational institutions to deliver quality instruction to their students in a crisis. The rapid instigation of advanced digital technologies to facilitate remote learning by universities and colleges provided a pedagogical bridge to cover the time and space restrictions forced on the normal face-to-face classroom experience. Unfortunately, as the impact of the pandemic has waned, educational institutions drew down their investments in the digital technology infrastructure, hardware, and software that were indispensable to sustaining student learning over the two years the pandemic interrupted normal educational schedules. However, it is argued that it would be extremely prudent to expand rather than contract these resources.  Research indicates that many teachers struggled with technologies in remote teaching during COVID-19.  This raises the question of how teacher education programs can adequately provide future teachers with essential digital literacy skills to teach in diverse technology-enriched learning environments.  The proposed frameworks aim to reshape the curriculum in teacher education programs to cultivate and develop preservice teachers’ digital literacy skills.
The Effectiveness of Local Potential-Based Learning Modules on Creative and Entrepreneurial Project Learning
Authors: Haswah  , Gani Hamsu Abdul , Mangesa Riana T.
Published: February 2024

Entrepreneurship education is a learning process that requires self-direction and self-management from Shiva. The purpose of this study is (1) to know the learning outcomes of students after using the learning module of creative and entrepreneurial projects; (2) to know the improvement of student learning outcomes. This type of research is experimental research. Experimental design using one group Pretest-Posttest Design with one class using a learning module with the provision of pretest at the beginning of learning and post at the end of learning. The subjects of this study were students of Class XI of Online Business Marketing at SMK 1 Bone Regency, totaling 35 people. The sampling technique used is purposive sampling. Analysis of the effectiveness of the n-gain test module. The results showed (1) the learning outcomes of students in field trials showed the tendency to learn very high category with a percentage of 42.86%; (2) the value of n-gain score in the experimental class of 0.48 then it can be concluded that there was an increase in learning outcomes with the medium category. Thus it can be said that the use of learning modules creative and entrepreneurial projects based on local potential is more effective than the products that have been used so far.
A New Type of Bivariate-Gamma Probability Function
Authors: Adeniran A. T.  , Faweya O.
Published: February 2024

This paper develops a New Bivariate-Gamma Distribution (NBGD) and explores its mathematical and statistical properties such as marginal probability distributions, moments, product moment, covariance and correlation. The study further investigates the various special cases of the NBGD. The new distribution is more robust with additional parameters and flexible for modelling real datasets.
On unique Fixed-Point Theorems via Interpolative and Rational Contractions in Super Metric Spaces
Authors: Gourh Rahul , Ughade Manoj , Shukla Manoj Kumar
Published: February 2024

In the present research paper, Kannan, Reich, and Dass-Gupta-type contractions are defined and discussed in the framework of super metric space. Further, some fixed-point results are proved using the notion of interpolation.
Duration of spermatogenesis and spermatozoan transport in the rabbit based on cytological changes, DNA synthesis and labeling with tritiated thymidine
Authors: Swierstra E. E. , Foote R. H.
Published: February 2005

The duration of spermatogenesis in the rabbit was determined by injecting in a single dose 1 millicurie of thymidine‐methyl‐H3 per kg into the marginal ear vein of each of 14 Dutch‐belted bucks. At different intervals, biopsies and unilateral castrations were performed on nine of the 14 bucks to time the stages of spermatozoan formation in the testis and transport through the epididymis. The remaining five animals were ejaculated for 63 days to determine the interval between the thymidine‐H3 injection and the appearance of the isotope in the ejaculated semen.

Histological sections, 8 μ thick, were stained with the Feulgen technique and coated with NTB 3 nuclear emulsion. The autoradiographs showed that the leptotene primary spermatocytes were the most advanced spermatogenic cells that incorporated the label. This agreed with microspectrophotometric determinations of DNA which showed this to be the last stage at which DNA was synthesized in spermatogenesis. Therefore there appears to be no DNA exchanged during spermiogenesis. Uptake of tritiated thymidine by spermatogonia also was in accordance with measurements of DNA synthesis and content of these cells.

Thirty‐one days post‐injection the label had progressed from leptotene primary spermatocytes to spermatozoa leaving the testis. At this time a few labeled spermatozoa also were present in semen smears taken from the caput epididymis. Epididymal transport time was eight days for one rabbit and ten days for four rabbits. The duration of one cycle of the seminiferous epithelium based on 55 estimates was 10.9 ± 0.1 days. The lifespan of type A spermatogonia, type 1 intermediate spermatogonia, type 2 intermediate spermatogonia, type B spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa was estimated to be 3.4, 0.6, 2.8, 1.1, 16.5, 0.8, 10.0 and 15.6 days respectively.

The estimated total duration of spermatogenesis in the rabbit depends on the point chosen as the onset of spermatogenesis. If spermatogenesis is considered to begin with the first of the series of spermatogonial divisions leading to the production of primary spermatocytes then about four cycles of the seminiferous epithelium or 4 × 10.9 = 43.6 days are required. However, if one assumes that spermatogenesis starts with the formation of spermatogonial stem cells and that the lifespan of these stem cells is one cycle of the seminiferous epithelium then spermatogenesis extends over about 4.75 cycles, or 51.8 days.
Oxidative enzymes of intermediary metabolism in healing bone fractures. A histochemical study
Authors: Balogh Károly , Hajek Joseph V.
Published: February 2005

The fibulae of young adult rats were cut at the mid‐diaphysis with scissors and examined at various stages of repair. The distribution of enzymes participating in glycolysis, in the citric acid cycle, and in the hexose monophosphate shunt was studied histochemically in healing bone fractures.

Three days after the fracture there was marked proliferation and an increased enzyme activity in the osteoprogenitor cells in the inner layer of the periosteum along the entire diaphysis. Remarkable enzyme activity was also observed in the newly formed osteocytes. No qualitative differences were noticed among osteoprogenitor cells, osteoblasts, and osteocytes. Necrotic muscle fibers, periosteum, and bone cells failed to react.

Seven days after the fracture, a bulky cartilaginous callus developed. The proliferating osteoprogenitor cells of the periosteum and of the callus had a similar enzyme pattern. As the fibroblast‐like osteoprogenitor cells of the callus developed into chondrocytes, enzyme activity increased. This was especially striking for isocitric dehydrogenase and glucose‐6‐phosphate dehydrogenase. When the chondrocytes became hypertrophic, they gradually lost enzyme activity. Mononuclear and multinuclear osteoclasts, macrophages and foreign body giant cells showed marked activity of most demonstrated enzymes. Glucose‐6‐phosphate dehydrogenase activity was marked in foreign body giant cells, but appeared weak in osteoclasts.

At 14 days the enzyme pattern of the callus was essentially the same as at seven days.

At 30 days bone union was well established, but there was still considerable osteoblastic and osteoclastic activity.

The histochemical findings have been described in detail and discussed in correlation with pertinent morphological and biochemical data. Histochemically, bone regeneration proved to be essentially a recapitulation of normal bone growth.
Phase microscopic observations of rat incisor enamel
Authors: Weber Dennis
Published: February 2005

Thin ground sections (4–10 μ) of rat incisor enamel were prepared in appropriate planes using a modified hand grinding technique. Phase microscopic observations of these sections confirmed the previously defined rod arrangement in the inner layer of enamel, and also demonstrated a high degree of structural orientation in the outer layer of enamel. The initial layer of enamel formed was found to present a morphologic picture which has not been previously defined: a series of inter‐connected pillars of enamel on an elevated base which has a “fish net” appearance in tangential section.
The study of calcification of mammalian cartilage in norm and pathology by stain historadiography
Authors: Bohatirchuk F.
Published: February 2005

The combined technique of histology and radiography — stain historadiography (Bohatirchuk, '57a) — was used for studies of cartilage calcification. The main advantages of the technique are: a. X‐ray specificity in the detection of calcium; b. the possibility of a morphological visualization of calcium in biological tissues at a microlevel. Three patterns of cartilage calcification were observed: 1. columnar; 2. expansive; 3. ubiquitous. Stain historadiographs suggest that the cartilage cell rather actively participates in the calcification: a. calcium deposits are often found within the cytoplasm and cell membrane; b. some cartilage cells are frequently entombed in intraosseous lacunae. The latter phenomenon is especially often observed in the ubiquitous type of calcification.
Hypothalamic neurosecretory system in the normal and partly or completely hypophysectomized goldfish
Authors: Sathyanesan A. G.
Published: February 2005

The nucleus preopticus (NPO) of the normal goldfish examined at intervals of three hours for a complete day exhibits marked variation in their affinity for aldehyde fuchsin (AF). Some times in this nucleus the cells of the pars magno‐cellularis were deeply stained while those of the pars parvocellularis were lightly stained, which suggests a functional difference. Both NPO and the nucleus lateralis tuberis (NLT) are AF‐positive in the goldfish. In the neurohypophysis three tinctorial types of Herring bodies were seen; the AF‐positive bodies can be traced back to the NPO but the origin of the fast green and acid fuchsin bodies is uncertain. In the hypophysectomized specimens without regenerating neurosecretory axons the NPO exhibited degenerative changes. However, if regeneration of the pituitary stalk occurred, forming a neurohypophysis‐like organ the NPO was apparently normal. Prominent AF‐positive granules were not obvious in the NLT of hypophysectomized specimens.
Bone formation and resorption around developing teeth transplanted into the femur
Authors: Hoffman Richard L.
Published: February 2005

Seven of 24 newborn hamsters developing maxillary molars which were transplanted to the femur for 28 days showed growth and development of crowns and roots. Enamel, dentin, pulp, cementum, periodontal ligament and alveolar bone proper developed in their normal locations just as they had done previously in molars transplanted into subcutaneous connective tissues. Several relationships were observed between alveolar bone proper, developed in the foreign body environment and under the inductive influence of the tooth root, and femoral bone. Femoral bone was continuous with alvolar bone and supported the tooth socket. In some areas near transplanted molar roots, femoral bone was built out to join and support alveolar bone. In other areas, femoral bone was resorbed by the development of a molar root or the molar root was diverted from its normal direction of development. Despite the effort to orient transplanted molars for eruption, the orientation was altered and no evidence for tooth eruption was observed.
A time sequence study of fat absorption in the rat jejunum
Authors: Jersild Ralph A.
Published: February 2005

Fat absorption and transport in rat intestinal epithelial cells were followed by electron microscopy and radioautography. Physiological fatty‐chyme, prepared from fat‐fed donor rats, was injected into ligated segments of the upper jejunum of fasting recipient animals. Samples of tissue were removed in a time sequence from 1 to 30 minutes. Oleic acid‐H3 was added to the chyme for light and electron microscopic radioautography. The results indicate that fat is absorbed and transported through the epithelium very rapidly. Within 1 minute, fat droplets can be seen in the endoplasmic reticulum and the Golgi apparatus. Fat is shown to be absorbed during, not prior to, experimentation by the radioautographic identification of labeling in the vicinity of fat droplets throughout the cell. Evidence of accumulation of fat within the Golgi apparatus appears between 1 and 2 minutes. Such accumulation may be indicative of a rate‐limiting step in absorption. It is suggested that phenomena occurring within the Golgi apparatus are in part responsible for the appearance of cellular saturation with fat, which is evident in 8 to 10 minutes. The sequential pattern can be followed in cells along the entire length of the villus.
Morphologic distinctions between oligodendrocytes and microglia cells in the rabbit cerebral cortex
Authors: Cammermeyer Jan
Published: February 2005

In the rabbit cerebral cortex, preserved by perfusion and stained by the silver carbonate method of Del Rio‐Hortega modified by Naoumenko and Feigin for paraffin sections, the oligodendrocytes are situated next to blood vessels or are placed at a short distance from the blood vessels, which they contact with a thickening.

The microglia cells are usually situated in juxtaposition to neurons and are rarely found along blood vessels. They give off long tortuous thick processes with delicate secondary branches, which contact numerous neighboring neurons and terminate either at short distances from branches of adjacent microglia cells or next to vascular walls. Although there are regional variations in the appearance and number of microglia cells, their processes are so profuse that they seem to supply all neurons; these processes cover a small portion of the neuronal surface.

In the cerebral cortex of the rabbit, the oligodendrocytes, because of their rare occurrence, would seem to have a more restricted function, while the microglia cells, because of their profuse distribution, seem to have a more universal function than is usually attributed to them.
Fine structure of the photoreceptor cells of the ground squirrel (Citellus tridecemlineatus tridecemlineatus)
Authors: Hollenberg Martin J. , Bernstein Maurice H.
Published: February 2005

The structure of the photoreceptor cells of the ground squirrel retina has been studied by light and electron microscopy. The ground squirrel photoreceptor cells are of particular morphologic interest because this mammal is believed to possess a pure cone retina. Light micrographs show that the ground squirrel retina possesses an unusually narrow outer nuclear layer, a characteristic feature of pure cone or predominantly cone retinae. By light microscopy all the photoreceptor outer segments appear uniform in size, shape and position and resemble cones more closely than rods. Electron micrographs of ground squirrel photoreceptor cells also reveal a uniform structure typical of cones of other vertebrates. Each of the photoreceptor outer segments is formed by flattened saccules lying one on top of the other and many of the saccules, as is characteristic of cones, are continuous with the overlying plasma membrane. The basal processes of the photoreceptor cells also are cone‐like in nature since each contains several synaptic lamellae and makes contact with a large number of dendritic processes arising from cells in the inner nuclear layer. It is concluded that the ground squirrel retina, from a purely morphologic standpoint, is exclusively or almost exclusively pure cone in type.
Spontaneous and diet‐induced hepatic fibrosis in mice of the C strain
Authors: Clower Ben R. , Williams W. Lane
Published: February 2005

Mice of the highly inbred C strain were used. Of these 146 were fed a completely adequate diet. These were 10–66 weeks old when killed. Beginning at 3–4 months of age 45 mice were fed a diet high in fat (40% lard), low in protein (8% casein) and deficient in lipotropic substances for 4–66 weeks.

Livers were not fatty in mice fed the adequate diet. Hepatic fibrosis developing within 24 weeks of age, and increasing with age, was observed in more than 60% of these control mice. Fibrosis was usually subcapsular, but in some instances was perivenous or intralobular. Reticular fibers were the chief component.

In those fed the atypical diet the livers were fatty in all mice killed during the 4–66 weeks of the study. At approximately 20 weeks liposis declined from the large amounts present earlier (4–18 weeks). Until 52 weeks most of the lipid was located in fatty cysts. Subsequently the livers became excessively fatty. Parenchymal necrosis was limited to three mice. Parenchymal hyperplasia was lacking.

In the dietary group of mice there were three patterns of hepatic fibrosis. Subcapsular fibrosis developed within a month and was the most common type. Another type consisted of fibrous septa extending chiefly from central veins. Linkage of septa produced pseudolobulation or pseudoencapsulation of areas of parenchyma. The least common type was an intralobular fibrosis which was unrelated to the capsule or to veins. All three types consisted initially of reticular fibers. Collagen was present in subcapsular and perivenous fibrosis within 16 weeks and in the intralobular type by 52 weeks.
The reactive oligodendrocyte. An electron microscopic study of cerebral cortex following alpha particle irradiation
Authors: Maxwell David S. , Kruger Lawrence
Published: February 2005

The ultrastructural features of oligodendrocytes have been studied in a zone of cerebral cortex in which all neurons are destroyed and numerous processes damaged by heavy ionizing particles. This type of lesion fails to reveal signs of vascular inflammation and classical “gitter cells” in light microscopy or any signs of debris fragments in electron microscopy. Oligodendrocyte satellites of neurons or their processes display an acute swelling associated with signs of neuronal damage. This is followed by a marked increase in a morphologically rich variety of dense osmiophilic organelles of granular, lamellar, crystalline or amorphous sub‐structure. Acid phosphatase activity has been demonstrated in some of these organelles, thus implying a participation in “lysosomal” intracellular breakdown. Invasion by microgliacytes and phagocytosis was not observed. Present evidence supports the efficacy of intracellular mechanisms in the breakdown of degenerating material and suggests a re‐evaluation of the evidence for identification of microglia on the basis of granular inclusions.
Electron microscope and ultracentrifugation studies on the rat reticulocyte
Authors: Beams H. W. , Kessel R. G.
Published: February 2005

Reticulocytosis was induced in rats by the daily injections of phenylhydrazine. The reticulocytes were studied by supravital staining, ultracentrifugation and phase‐contrast and electron microscopy. Electron micrographs of sectioned reticulocytes reveal the presence of hemoglobin, polyribosomes, mitochondria, micropinocytosis vesicles, tubules of varying size and, in some cases, Heinz body material. When subjected to ultracentrifugation these materials are readily stratified in the order of their relative densities from the centrifugal to the centripetal end as follows: hemoglobin, mitochondria, ribonucleoprotein material (ribosomes) and Heinz body material. The centrifuged reticulocytes may be stretched two or three times their normal diameter and even pulled into two parts without hemolysis. Of interest is the observation that in ultracentrifuged reticulocytes, the ribosomes are not displaced from the region of the cortex, a condition which is interpreted as strong evidence that this region is of a greater consistency (viscosity) than the remainder of the cell. Evidence was observed to show that as maturation of the reticulocyte occurs, the cell gradually decreases in size and increases in density; concomitantly with these changes is a progressive degradation of the mitochondria and ribonucleoprotein material, so that by the time the erythrocyte stage is reached, these materials seem to have completely disappeared.
Studies on sperm survival mechanisms in the female reproductive tract of hibernating bats. I. Cytology and ultra‐structure of intra‐uterine spermatozoa in Myotis lucifugus
Authors: Wimsatt William A. , Krutzsch Philip H. , Napolitano Leonard
Published: February 2005

Among mammals prolonged survival of spermatozoa in the reproductive tract of the female (circa 7 ± months) is known in only a few species of hibernating bats, but its physiological basis remains obscure. Presumably survival involves special physiological adaptations of the spermatozoa, the uterus, or both. We have initiated studies of sperm survival mechanisms in the hibernating bat Myotis lucifugus involving analysis of the cytology and fine structure of intra‐uterine sperm, the morphology and histochemistry of sperm‐uterus interactions, and selected biochemical parameters of the reproductive tract. This paper summarizes our findings concerning the morphology of epididymal and intra‐uterine spermatozoa, and emphasizes those aspects not detailed by others. The microscopic organization of epididymal sperm is described in detail with particular attention to peculiarities of the head, middle piece and cytoplasmic droplet. The latter contains amylase‐resistant PAS+ granules and acid phosphatase, both possibly of lysosomal origin. Most ultrastructural features elucidated by Fawcett and collaborators are confirmed, but additional details concerning the head, post‐nuclear sheath, origin of axial filament complex, and the outer coarse fibrils are provided. A functional interrelationship between coarse fibrils 3 and 8 and the longitudinal columns of the fibrous sheath is also postulated.

Structural differences between epididymal and uterine sperm are minor, suggesting that uterine environmental factors are most important for sperm survival.

A new basis is suggested for the apparent helical arrangement of mitochondria in the middle piece; in Myotis sperm the configuration is illusory, being the result of an orderly alternation in the staining of the serially arranged mitochondrial pairs. We suggest that the “patterned” staining of mitochondria may reflect sequential, cyclic functional alterations of significance in the initiation and/or coordination of the geometrically oriented tail movements.
Septal projections to nuclei functioning in oxytocin release
Authors: Powell Ervin W. , Rorie Duane K.
Published: February 2005

Terminal degeneration was observed in the paraventricular and supraoptic nuclei of the hypothalamus following lesions in the septum of the squirrel monkey. The degeneration was usually greater in the supraoptic nucleus. A lesion in the posterior dorsal septum resulted in more degeneration in the paraventricular nucleus. Lesions in the dorsal gyrus rectus, genu of the corpus callosum and extreme rostral septum resulted in no identifiable degeneration in the two nuclei. These nuclei have been shown by various investigators to facilitate milk ejection (oxytocin release). Stimulation of the mesencephalic central gray has been shown to influence oxytocin release. Following a lesion in the mid‐septal area, degenerating terminals were seen in the mesencephalic central gray. Our results show that the septum is directly connected with the supraoptic and paraventricular nuclei and mesencephalic tectum. Possibly the septum functions in modulating mechanisms having to do not only with lower autonomic responses such as blood pressure, and bladder emptying, but oxytocin release as well.
Skeletal changes in murine runt disease
Authors: Simmons David J. , Simmons Richard L.
Published: February 2005

Runt disease was produced in neonatal F1 hybrid mice by the injection of spleen cells from a mature donor of the parental strain. Clinically apparent runting appeared after the tenth day. Mice were serially sacrificed when 11–19 days old, and their long bones were examined histologically and histochemically. In runt disease, development of the epiphyseal secondary centers of ossification was retarded. The cells and protein polysaccharides did not mature normally, and the tissue contained acellular cartilage. Accumulations of hypertrophic chondrocytes signified impaired endochondral ossification. While the osteogenic cells in the medullary spaces had been replaced largely by mononuclear lymphoid cell infiltrates, bone collagen was present on unremodeled metaphyseal trabeculae which possessed wide cartilage cores. The intertrabecular spaces were moderately fibrotic. Large remnants of unossified unresorbed cellular cartilage were frequently observed in the metaphysis. It appeaed that the generalized graft‐versus‐host reaction induced by the spleen cell “grafts” was extended to the skeleton, but that the changes in the cartilage and bone tissue had occurred largely before the onset of clinical runting.
The fine structure of vascular sympathetic neuromuscular contacts in the rat
Authors: Devine C. E. , Simpson F. O.
Published: February 2005

The fine structure of the neuromuscular contacts of arterioles and small arteries from the jejunum and mesentery of the rat has been studied. There is a rich innervation of these vessels, consisting of bundles of axons in the adventitia around the vessels.

In the typical sympathetic neuromuscular contact on a small blood vessel, the axon bundle is loose, the Schwann cell cover is deficient, the neuromuscular distance is less than 1,500 Å, the basement membranes of axon and smooth muscle cell are fused together, and the axon tends to follow the contour of the smooth muscle cell. However, it is not possible to be certain that these criteria are essential for a true functional neuromuscular contact. In particular, it appears from the structural findings that a neuromuscular distance of 2,000–3,000 Å or more could well be compatible with effective neuromuscular transmission.

Smooth muscle cells in arterioles often have multiple innervation, and an axon probably innervates more than one smooth muscle cell.

Occasional axons contain mainly or solely vesicles of the “large granular” type.
Induction of ovulation in the pregnant hamster
Authors: Greenwald Gilbert S.
Published: February 2005

Pregnant hamsters consistently ovulated when injected with 20 IU of human chorionic gonadotropin (HCG). The induced ovulation rate from days 4–8 of pregnancy was comparable to that observed during the estrous cycle; however, starting at day 10, a marked increase occurred, culminating in a peak of 35 ova at day 12. Animals injected with HCG on day 16, the day before delivery, ovulated an average of 14.5 ova, although spontaneous postpartum ovulation does not occur in the hamster. The number of ovulations induced by HCG correlated with the varying number of antral follicles present during different stages of pregnancy.

Unilaterally ovariectomized pregnant hamsters did not show a compensatory increase in induced ovulation rate in the remaining ovary.

The induction of ovulation on days 4 or 10 of pregnancy did not interfere with embryonic development nor influence the time of parturition. Following parturition, the primary and induced corpora lutea regressed synchronously.
A morphological and histochemical study of the primary and secondary immune responses in the rat spleen
Authors: Pettersen James C. , Borgen Daniel F. , Graupner Kenneth C.
Published: February 2005

Macrophages and cells of the plasmocyte series were studied in the rat's spleen during the primary and secondary immune responses to particulate antigen. Evidence is presented to suggest that the plasma cell precursors are located in the marginal zones surrounding the lymphoid nodules and that less than one day following injection of antigen, these cells migrate into the nodules, where mitosis and subsequent differentiation into hemocytoblasts occurs in the presence of nodular macrophages. The hemocytoblasts then migrate across the marginal zone into the red pulp where differentiation into mature plasma cells occurs in the presence of red pulp macrophages. It is suggested that the initiation of the antibody‐forming process occurs in the lymphoid nodules where marginal zone cells come into close contact with the marginal metalophils or with germinal center macrophages. The process initiating the migration of cells from the marginal zone to the nodules is unknown.
Fine structure of steroidogenic cells of a primate cutaneous organ
Authors: Sisson Jean Kneeland , Fahrenbach Wolf H.
Published: February 2005

The antebrachial organ of the ring‐tailed lemur (Lemur catta) is a highly differentiated cutaneous appendage composed of atypical apocrine sweat glands and of clumps of large interstitial cells. These cells have many similarities to steroid‐secreting cells, most notably an extensive agranular reticulum, which occurs in several forms. Commonly it consists of random tubules, but at times these are compacted into tight masses. The cisternae sometimes are distended with dense inclusions. Often the agranular reticulum differentiates into a rigidly patterned crystalloid composed of stacked layers of parallel, interconnected tubules. The three‐dimensional structure of the crystalloid is identical in both sexes, but the crystalloid of the male is scaled down in all its dimensions by a factor of about 0.9 as compared to that of the female. The interstitial cells, like steroidogenic tissue, exhibit intense 3β‐, 17β‐, and 20α‐hydroxy‐steroid dehydrogenase activity and contain abundant esterases; thiobutyric esterase activity is limited to the agranular reticulum.

For comparative purposes, examination has been made of several other tissues having agranular reticulum: testicular interstitial cells, corpus luteum, adrenal cortex, and sebaceous cells of Lemur catta, rat meibomian glands, and the Leydig cells of human testis. The Reinke crystalloid of human testicular interstitial cells is totally unlike the crystalloid of the interstitial cell of the antebrachial organ.
Striated muscle cells in the thymus of reptiles and birds: An electron microscopic study
Authors: Raviola Elio , Raviola Giuseppina
Published: February 2005

Striated muscle cells, the “myoid cells” of light microscopic literature, are consistently found in the thymus of reptiles and birds. Round or elongated myoid cells resemble adult skeletal or cardiac muscle fibers; however, the location of the nucleus, the course of the myofibrils, the arrangement and proportion of the thick and thin filaments, and the morphology and topography of the membranous components of the sarcoplasm are variable. Other myoid cells which contain either primitive myofibrils, irregular bundles of myofilaments associated with primitive Z plaques, or thick and thin filaments alone scattered throughout the cytoplasm, recall the various stages of the development of skeletal and cardiac muscle fibers. In these cells the ribosomes are often, but not always abundant and appear in places arranged in helices and rosettes. It is suggested that a postnatal myogenesis takes place in the thymus. Anomalous muscle cells contain thin filaments almost exclusively. In some of these cells, thin filaments are arranged in I‐segments that appear either independent of each other or interdigitated in pseudosarcomeres. Finally, some myoid cells appear to have degenerated. Desmosomes join myoid cells to reticular cells, to other myoid cells, and to epithelial cells in the walls of intraparenchymal cysts. The origin of the myoid cells from reticular cells is suggested.
The relationship of nucleotidase activity to catecholamine storage sites in adrenomedullary tissue
Authors: Wood Joe G.
Published: February 2005

Tissues were either fixed in 3% glutaraldehyde and treated histochemically to demonstrate nucleotidephosphatase activity and catecholamines or in 2.5% potassium dichromate (pH 4.1) for demonstration of catecholamines. Frozen sections (10 μ) were examined with the light microscope or following the histochemical procedures 1 mm cubes of tissue were treated with 1% OsO4 and prepared for electron microscopy.

Light microscopy demonstrates groups of norepinephrine cells in adrenal medullary tissue of cats and rats. Nucleotidetriphosphatase activity is found along nerve fibers, between epinephrine cells and concentrated in norepinephrine cell areas. The same is true for diphosphatase localization but with less intense activity. Nucleotidemono‐phosphatase activity is located primarily at the site of norepinephrine cells.

Electron microscopy shows triphosphatase activity along membranes of chromaffin cells and nerve fibers, at canaliculi and nerve terminals, and in sinusoidal cells. Diphosphatase activity is present at similar sites and shows some intracellular activity. Monophosphatase activity is present at cell membranes and intracellularly appears closely related to catecholamine storage granules. It is postulated that since nucleotides are apparently instrumental in the binding of catecholamines, nucleotidephosphatase action effects a mechanism of catecholamine release from the storage sites and permits passage through the cell membranes.
An autoradiographic study of satellite cells in autonomic ganglia
Authors: Schwyn Robert Conrad
Published: February 2005

This investigation was undertaken to observe and to correlate the responses of satellite cells in autonomic ganglia to increased neuronal and synaptic activity. By electrically stimulating preganglionic nerve fibers terminating in the superior cervical sympathetic ganglion in 19 adult cats and concurrently injecting thymidine‐H3 into the stimulated animal, it was possible to alter the neuronal and synaptic activity within the superior cervical ganglion and subsequently observe from autoradiograms the cellular absorption of thymidine‐H3. The specific reaction encountered was incorporation of thymidine‐H3 into the nuclei of satellite cells. Absorption of thymidine by satellite cells and incorporation of this compound into their nuclear structure could be accelerated or inhibited by exposing the organism to specific drugs (viz. neostigmine and atropine sulfate) during the stimulatory period.

The results of this investigation combined with information gathered from studies in many other scientific areas implicate satellite cell participation in response to increased neuronal metabolism and possibly to increased synaptic activity. Satellite cells apparently proliferate to cope with the demands of increased ganglionic activity elicited by the experimental procedures employed in this study. Although specific reactions of satellite cells other than cellular proliferation were not identified in this study, their probability may provide a basis for further investigation.
Origin and distribution of portal blood in the sheep
Authors: Heath Trevor
Published: February 2005

In sheep, the gastrosplenic and mesenteric veins converge at an angle of about 140° to form the portal vein, which is joined, along its right ventral border, by the gastroduodenal vein. At the porta, right and left branches of the portal vein diverge at an angle of 65–70° to supply separate areas that join along a line between the fossa for the gall bladder, and the middle of the left branch. Right dorsal branches leave the portal vein or its right branch near the point of bifurcation.

When 131I‐albumin that had been heated was injected into the right ruminal vein and entered the portal stream in the gastrosplenic vein, no significant differences existed in the levels of radioactivity between the areas supplied by the different portal branches. When the 131I‐albumin entered the portal stream from either the gastroduodenal or mesenteric veins, the area supplied by the right branch contained a significantly higher level of radioactivity than the remainder of the liver. When corrections were made for an unequal distribution of blood, it was found that blood from the gastrosplenic vein was distributed preferentially to the left branch, blood from the gastroduodenal vein to the right branch, and that blood from the mesenteric vein enters the right and left branches in preference to the right dorsal branches of the portal vein.
Histochemical investigation of fiber type ratios with the myofibrillar ATP‐ASE reaction in normal and denervated skeletal muscles of guinea pig
Authors: Karpati G. , Engel W. King
Published: February 2005

The myofibrillar ATPase histochemical reaction was utilized to determine the proportion of the two basic histochemical fiber types in three “mixed” skeletal muscles of guinea pig after denervation. In five normal control animals, there was no significant difference in the proportion of fiber types on the two sides. In 12 experimental animals from 6–27 weeks after right sciatic neurectomy, the intensity of the myosin ATPase activity was not appreciably altered in the denervated muscle fibers but the type II (dark) fibers underwent preferential atrophy. The fiber type ratio between denervated and control sides in the experimental animals was not significantly different from the same values in the normal control animals. This allowed the conclusion that, up to 27 weeks after denervation, the histochemical typing of a fiber by the myofibrillar ATPase reaction probably reflects the original fiber type. This reaction is the preferred method for fiber typing in denervated guinea pig muscle, especially since most other histochemical reactions show markedly reduced activity of muscle enzymes after denervation and are unsuitable for fiber typing. The soleus, which normally contains only type I fibers, showed numerous type II fibers at 27 weeks after denervation and this was interpreted as a dedifferentiating process.
Gonocyte degeneration in the postnatal male rat
Authors: Roosen‐Runge Edward C. , Leik Jean
Published: February 2005

The cell population of the sex cords in rat testes from day 1 to day 10 after birth was investigated by means of microscopic observation and quantitation, and with the electron microscope. Certain gonocytes, rare during the first 2 days, more frequent thereafter, were found in various stages of pyknosis. In electron micrographs these were characterized mainly by condensed and sometimes fragmented nuclei and cytoplasmic vacuoles and vesicles. The mitochondria remained typical of gonocytes in all but the most advanced stages of necrosis. Degenerating cells were eventually surrounded by single supporting cells and apparently phagocytized by them. Gonocytes which appeared “swollen,” “fuzzy” and pale staining under the microscope were considered normal pre‐mitotic cells or possibly in some cases altered by artifacts of fixation. No evidence was produced microscopically or electron microscopically that cells of this type are degenerative. In many gonocytes, the electron microscope revealed some swollen mitochondria with irregular cristae, “B‐bodies” in varying numbers and occasional membrane breakage. The evidence was considered insufficient to interpret these as signs of impending cell death.

Quantitative determinations of the numbers of gonocytes at various stages indicate that approximately one third of the cells are lost between day 1 and 4 post‐partum. In Sprague‐Dawley rats gonocytic mitoses resume on day 4. There is evidence that degeneration of gonocytes continues until day 7 or 8. The total number of cells dying may possibly be accounted for by the number of pyknotic cells observed. Incidental data are reported concerning the growth of sex cords and the proliferation of supporting cells. Comparison with results in the literature lead to the general conclusion that there is excellent evidence that many gonocytes die during the first postnatal week, but that many of the morphological criteria for dying cells used by previous investigators lack validity when rigorously examined.
The vascularization of the hypothalamic‐hypophyseal region of the eastern brook trout, Salvelinus fontinalis
Authors: Hill Joanna Jensen , Henderson Nancy E.
Published: February 2005

The hypophysis of the brook trout is irrigated by blood vessels which originate from the internal carotid arteries. These are: (1) branches of the ventral hypothalamic arteries that give rise to an extensive capillary plexus in the neurohypophysis from which vessels extend into all regions of the adenohypophysis; (2) branches of the caudal hypothalamic artery that irrigate the saccus vasculosus and continue anteriorly to supply the ventral areas of the meta‐adenohypophysis; (3) a caudal hypophyseal artery which vascularizes a portion of the meta‐adenohypophysis however, this vessel is not always present; (4) a pair of small arteries which supply the peripheral regions of the gland directly from the carotids.

Most of the neurosecretory fibers of the preoptic‐hypophyseal tract terminate close to capillaries in the neurohypophysis. A few axons extend into meso‐adenohypophyseal tissue. It is suggested that the secretory activities of the pro‐, meso‐ and metaadenohypophyses are governed by hypothalamic factors that are chiefly transmitted to the gland cells via the vascular system (indirect control). However, the activity of the meso‐adenohypophysis may also be regulated by factors which are transmitted directly to the cells from the endings of neurosecretory fibers which have traversed the neurohypophysis (direct control). The distribution and abundance of neurosecretion in the ventral hypophysis suggest the possibility of storage of hypothalamic products within this region.
The fine structure of the hamster pineal gland
Authors: Sheridan Michael N. , Reiter Russel J.
Published: February 2005

The pineal gland of the hamster has been examined with the electron microscope. The gland is composed of two types of parenchymal cells, a “light” and a “dark” cell. Blood vessels are infrequently encountered and display little perivascular space. Axons, nerve endings, pineal cell processes, and occasional glial processes ramify within the parenchyma of the gland.

The parenchymal cells display abundant mitochondria, many with a tubular internum. Smooth and rough surfaced endoplasmic reticulum, a Golgi apparatus and lipid droplets are regular features of both cell types. Vesicles of varying size and containing electron dense centers are present in the cell body.

Parenchymal cells branch extensively and are characterized by the presence of microtubules in addition to the usual organelles encountered in the cell body. Pineal cell process terminations regularly show accumulations of vesicles with electron dense granulations.
The embryonic origin of the abdominal (ventro‐lateral) musculature in the albino rat
Authors: Parry William
Published: February 2005

A study comprising both descriptive and experimental data was undertaken. The descriptive portion utilizes transverse, sagittal, and frontal serial sections of 10 through 20 day old rat embryos.

As development proceeds, the somites lengthen along their dorsoventral dimension, and epithelial‐lined “buds” (ventral somite buds) extend into the lateral plate somatopleure. Concomitantly epithelium lining the somite “body” is converted to a loosely associated mass of mesenchyme, beginning at the deep medial border and extending around the cephalic and caudal faces of the somite to involve the superficial surface. Lastly, this process transforms the epithelium covering the ventral somite buds into a mesenchymal aggregation. Anlagen of the abdominal ventrolateral muscles arise in the precise position of the mesenchymal aggregation derived from the ventral somite buds.

The experimental section tests the development capacities of isolated portions of the trunk body wall when implanted in the anterior chamber of the eye. Grafts of somite material are highly proficient in forming striated muscle, while grafts of somite‐free somatopleure have little ability to form striated muscle. Grafts of ventral body wall become more proficient in forming striated muscle with age. The increase in muscle‐forming ability correlates directly with the invasion of material from the ventral somite buds into the ventral body wall. It is concluded that the ventrolateral (abdominal) musculature is of somitic origin.
The subcutaneous implantation of autogenous rat molars
Authors: Irving James T. , Bond James A.
Published: February 2005

Maxillary molars were extracted, and decalcified or devitalized prior to subcutaneous implantation in the same animals. All molar implants attracted large numbers of leukocytes during the first week of implantation. After two weeks small basophilic mononuclear cells appeared which penetrated the dentinal tubules of decalcified molars and were associated with considerable resorption of dentin and predentin. Giant cells were not usually observed near decalcified molars, but large numbers of them were attracted to FDNB treated molars. Giant cells appeared in moderate numbers around devitalized molars and were associated with resorption of intact root surfaces after 56 days. The significance of these results is discussed.
An electron microscopic study of uterine arteries during pregnancy
Authors: Albert Ernest N. , Pease Daniel C.
Published: February 2005

The mesometrial arteries of pregnant guinea pigs are not mere blood conducting channels. Instead they are dynamic in nature. The cells forming the intima and media exhibited significant structural modifications during pregnancy. The endothelial cells became hypertrophied and attenuated. Their cytoplasm showed an increase in the amount of ribosomes, rough endoplasmic reticulum and lysosome‐like bodies during pregnancy. Dense bodies that were often closely associated with the Golgi apparatus were seen in pregnant animals. These bodies exhibited a graduation in size within each cell and were thought to be the precursors of the lysosome‐like bodies. Similar structures were also seen in smooth muscle cells of the mesometrial arteries of pregnant animals.

The endothelium of these arteries was often discontinuous in full term pregnant animals. In that case, the underlying smooth muscl4 cells provided the lining surface. Irrespective of which type of cells formed the lumen of these arteries, they became coated with a “fuzzy” layer which specifically stained intensely with phosphotungstic acid, suggesting that this layer might be a mucoprotein. The smooth muscle cell of the arterial media also became hypertrophied during pregnancy. The cytoplasm exhibited a gradual increase in free ribosomes and rough endoplasmic reticulum, mitochondria and microtubules throughout pregnancy. During the latter half of pregnancy many smooth muscle cells developed extensive amounts of smooth endoplasmic reticulum whose vesicles often were filled with an electron opaque secretory material. It is suggested that the development of unusually large quantities of smooth endoplasmic reticulum might be associated with steroid metabolism. Unusually thick basement membranes were formed around the modified smooth muscle cells of full term pregnant animals and the surfaces of these cells often exhibited large numbers of microvilli. The microvilli seemed to disrupt the continuous patterns of the basement membrane.