bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating Occupational Safety and Health Information Into Vocational and Technical Education and Other Workforce Preparation Programs
Authors: Schulte Paul A. , Stephenson Carol Merry , Okun Andrea H. , Palassis John , Biddle Elyce
Published: February 2005

The high rates of injury among young workers are a pressing public health issue, especially given the demand of the job market for new workers. Young and new workers experience the highest rates of occupational injuries of any age group.

Incorporating occupational safety and health (OSH) information into the more than 20 000 vocational and other workforce preparation programs in the United States might provide a mechanism for reducing work-related injuries and illnesses among young and new workers. We assessed the status of including OSH information or training in workforce preparation programs and found there is an inconsistent emphasis on OSH information.
Evidence of a Dose—Response Relationship Between “truth” Antismoking Ads and Youth Smoking Prevalence
Authors: Farrelly Matthew C. , Davis Kevin C. , Haviland M. Lyndon , Messeri Peter , Healton Cheryl G.
Published: February 2005

Objectives. In early 2000, the American Legacy Foundation launched the national “truth” campaign, the first national antismoking campaign to discourage tobacco use among youths. We studied the impact of the campaign on national smoking rates among US youths (students in grades 8, 10, and 12).

Methods. We used data from the Monitoring the Future survey in a pre/post quasi-experimental design to relate trends in youth smoking prevalence to varied doses of the “truth” campaign in a national sample of approximately 50000 students in grades 8, 10, and 12, surveyed each spring from 1997 through 2002.

Results. Findings indicate that the campaign accounted for a significant portion of the recent decline in youth smoking prevalence. We found that smoking prevalence among all students declined from 25.3% to 18.0% between 1999 and 2002 and that the campaign accounted for approximately 22% of this decline.

Conclusions. This study showed that the campaign was associated with substantial declines in youth smoking and has accelerated recent declines in youth smoking prevalence.
Stereotaxic localization of supraoptic, ventromedial and mamillary nuclei in the hypothalamus of weanling to mature rats
Authors: Bernardis Lee L. , Skelton Floyd R.
Published: February 2005

Bilateral symmetrical electrolytic lesions were placed in the supraoptic, ventromedial and mamillary areas in groups of albino rats weighing 50, 100, 150, 200, 250 and 300 gm.

The localization of the lesions was correlated with the coordinate setting used with the stereotaxic instrument.

The diagrams presented contain the data for the antero‐posterior, lateral and dorso‐ventral coordinates plotted against the body weight of the respective groups and allow the extrapolation of coordinates for other hypothalamic structures.
The arterial system of the head and neck of the rhesus monkey with emphasis on the external carotid system
Authors: Castelli Walter A. , Huelke Donald F.
Published: February 2005

The arterial plan of the head and neck of 64 immature rhesus monkeys (Macaca mulatta) was studied using four techniques — dissection, corrosion preparations, cleared specimens, and angiographs. In general, the arterial plan of this area in the monkey is similar to that of man. However, certain outstanding differences were noted. The origin, course, and distribution of all arteries is described as well as the vascular relations to pertinent structures.
The shape of rat kidney tubular cells
Authors: Bulger Ruth Ellen
Published: February 2005

Many cells specialized for ion transport have complex shapes. The cells of the nephron are no exception. Besides the well‐documented lateral processes seen in the basal region of many tubular cells, two further specializations are found in rat kidney tubular cells which serve to increase the lateral cell membrane area. These are an interdigitation of processes confined to the apical region, and an inter‐digitation of more extensive processes that extend the full height of the cell.
Coronary arteries of gallus domesticus
Authors: Lindsay Flora E. F. , Smith Helen J.
Published: February 2005

The pattern of the coronary arteries of the domestic fowl is described. In the fowl heart the longitudinal sulci do not contain descending rami of the coronary arteries. The largest coronary vessels are the right and left deep coronary arteries, which early in their course come to lie on the ventral face of the I–V septum immediately below the endocardium. The circumflex arteries which occupy the corresponding coronary sulci are minor trunks. Differences in the relative distribution of me right and left deep coronary arteries allow recognition of three heart types: Heart Type Two, i.e., right coronary artery dominance, is found to be the commonest; Heart Type Three (left coronary artery dominance), and Heart Type One (balanced coronary circulation) are less common. Some details of the origin and course of the atrial, infundibular, conal and valvular arteries are given. The presence of homo‐coronary and intercoronary anastomoses is noted.
A kinetic study of the myenteric neurones. Size variations in the neurovegetative periphery with body weight and organ size
Authors: Dupont Jean‐René , Jervis Helen R. , Sprinz Helmuth
Published: February 2005

The relationship between organ size, body weight and the size variations in myenteric neurones of the ileum and cecum has been studied in white Fisher rats. Three groups of conventional as well as germfree rats of varying body weight were utilized.

Myenteric neurones in the cecum and ileum “grow” with increasing body weight. Cecal neurones have a steeper growth curve than ileal neurones. The average diameter of Auerbach's ganglion cells in the cecum is 13.6 μ in 90 gm rats, 20.0 in 300 gm rats. In medium sized rats (150 gm) the myenteric neurones of the germfree cecum are 2–3 times as large as those in the cecum of conventional animals. This increase is proportional to the enlarged cecal circumference in germfree rodents. When small (90 gm) germfree rats are conventionalized the myenteric neurones return to normal size as the cecum “shrinks” to normal size. In the intramural parasympathetic nervous system of the gut organ size as well as body weight are determinants of ganglion cell size.
The pattern of the microcirculatory bed in the ventricular myocardium of domestic mammals
Authors: Brown Roger E.
Published: February 2005

Observations, as determined by injections of India ink through the coronary arteries of isolated and perfused beating hearts, were presented. Tissue blocks were removed from the right and left ventricular walls and the interventricular septum, sectioned and cleared for microscopic examination and photomicrography. The term microcirculatory bed was defined as those vessels 100 μ and smaller in diameter. The descriptions were based on 76 normal adult hearts of both sexes of six domestic species.

The arterioles divided by dichotomous branching until the final division resulted in two daughter capillaries. At no time was a capillary observed leaving an arteriole larger than 15 μ in diameter. The arterioles had a modified type of end artery pattern. Arterial anastomoses were uncommon in the areas and species examined. A specific area of a cardiac muscle fascicle was supplied by several arterioles whose capillaries intermeshed. The implications of this concept in relation to micro‐embolism were explored.

Capillary anastomoses were frequent but the connecting vessel was only about 20 μ in length. Three types of capillary anastomoses were identified. Capillaries did not cross the muscle fascicles of the myocardium.

Collecting venules were often distinctive in their morphological pattern. “Turnip root” patterns were observed in all species and represented the local venous collection of a muscle fascicle. A venule's capillary components were usually from several arteriolar sources.

Supported in part by research grant HE 04217‐05 from the National Heart Institute, U. S. Public Health Service.
The transverse tubular system in mammalian myocardial cells
Authors: Simpson F. O.
Published: February 2005

The fine structure of ox myocardial cells, as seen in transverse sections, is described. The presence of an extensive system of transverse tubules at Z region levels has been confirmed, the walls of the tubules being continuous with the sarcolemma.

Preliminary observations in smaller animals indicate that similar tubules are readily seen in guinea‐pig myocardial cells and are present, but are more difficult to find, in the rat; communication between the tubules and the exterior is readily demonstrated in the guinea‐pig but less readily in the rat.

Contact between the transverse tubules and the Z regions was not particularly close, and a thin delicate “circumferential Z tubule” was noted to lie round the myofibrils at most Z regions.

The Z regions, on cross section, shows a tightly packed square array of filaments, double in number compared with the thin filaments seen elsewhere in the sarcomere; the appearances probably confirm for heart muscle the Z region structure which has been described for skeletal muscle.
Mitosis and differentiation in the stratified squamous epithelium of the rat esophagus
Authors: Marques‐Pereira J. P. , Leblond C. P.
Published: February 2005

The fate of the cells of the stratified squamous epithelium of the esophagus was investigated radioautographically in young adult rats at various time intervals after a single injection of thymidine‐H3.

Soon after injection, labeled cells appeared in the basal layer of the epithelium (stratum basale). During the following 12 hours, the labeled cells completed DNA synthesis and mitosis, and mostly remained in the basal layer. After 12 hours, however, the labeled cells arising from the mitoses were transferred to the spinous layer (stratum spinosum) at the rate of 1.2% per hour.

The respective fates of the two daughter cells of a mitosis were then examined using two‐dimensional maps showing the location of the labeled nuclei at 24 and 48 hours after injection. It was assumed that any two nuclei located side by side and overlaid by a similar number of grains are the two daughter cells of a mitosis. Such pairs of labeled daughter cells fell into three categories: (1) Basal pairs, composed of two basal cells; (2) Outgoing pairs, composed of two spinous (or granular) cells; and (3) Mixed pairs, composed of one basal and one spinous (or granular) cell. Since three possibilities were encountered at the two time intervals, the mitoses could not be differential (in which case the pairs of daughter cells would consist of a cell remaining in the basal layer and another migrating to the spinous layer, that is, all pairs would be “mixed”). Instead, the frequency of the three types of pairs was such as to indicate that the transfer of a basal cell to the spinous layer is a chance event which can affect any basal cell (except those undergoing DNA synthesis or mitosis). Accordingly, the transfer of either or both daughter cells of a mitosis would also be due to chance.

The transfer of a cell out of the basal layer is a critical step in the life of the cell, since it precludes further division and appears to trigger differentiation.
Some structural and developmental characteristics of cetacean (odontocete) radii. A study of adaptive osteogenesis
Authors: Felts William J. L. , Spurrell Francis A.
Published: February 2005

Odontocete radii are short, flattened, longer than the humeri, and lacking in open medullary cavities. Their cross‐section is essentially a semi‐streamlined wedge. End‐on articulation at the elbow is a synchondrosis. In the streamlined, amuscular antebrachium, the radius sustains loadings predominantly in the mediallateral transverse plane as flipper movements (at the shoulder) counter body inertia and water resistance in controlling body attitude.

This study treats secondary marine adaptation as reflected in radial development, growth and mechanical organization. Early osteogenesis is similar to that we reported for cetacean humeri, and parallels conditions in the manatee. Later differential growth is analyzed in extenso. Geometry of growth is visualized radiographically in the relationship of endochondral to periosteal bone in the absence of medullary cavitation. Furthermore, the neonatal outline is distinguishable within the porous structure of (only) beluga radii, so that pre‐ and postnatal phases may be differentiated. Radiographs and models demonstrate that as elongation occurs, circumferential increments to growth cartilages are eccentric, i.e., minimal anteriorly, moderate medially and laterally and maximal posteriorly. By this method, the centers of epiphyseal cartilage plates migrate posteriad with time. Periosteal depositions follow the same pattern and are deepest posteriorly. Eccentric growth of the ulna is in the opposite sense. Additionally, proximal growth cartilages of radii tilt posteriad as the bone elongates. Some alterations in growth occur at birth and later. Eccentric growth is an adaptation by which anterior and posterior margins, respectively, of radius and ulna move apart as the bones elongate, and by which functional cross‐sections are maintained in antebrachial bones, singly and as a pair.

Bone is concentrated on medial and lateral sides of the radius. This feature, and porosity of the central region, varies with species. Radii, like humeri, thus mimic an engineered box‐beam, and trabecular orientation resembles trajectorial distribution in a loaded beam.

Radii have higher absolute densities than do humeri, although both bones have the same range of mineralization as typical mammalian bones. The beluga radius is half again as dense as that of the pilot whale, and thus is intermediate in density between those of most odontocetes and that of the hypothyroid, pachyostotic manatee. The possible evolution of odontocete bones from a more dense dense form, as well as the phylogenetic implications of density changes, are discussed. It is suggested that some of the characteristics of growth and structure, including an apparent periodicity in structural density, may be related to temperature and vascular supply in the high‐area, low‐volume flipper in colder waters.
Development of the flank organ (scent gland) of the Syrian hamster II. Postnatal development
Authors: Thomas Algard F. , Dodge Alice H. , Kirkman Hadley
Published: February 2005

In the first paper of this series, the prenatal development of the flank organ (scent gland) of the Syrian hamster was described. The present paper is concerned with the postnatal development of this organ. The embryology of the organ actually continues into postnatal life, until, during the fifth day, the organ attains the degree of development characteristic of general body skin at birth. Subsequently, an accelerated growth rate results in a conspicuous and characteristic hypertrophy of the gland relative to surrounding integument. During the acquisition of this hypertrophy two opposite developmental gradients are involved, i.e., a series of consecutive centripetal waves of hair cycling and a centrifugal gradient of sebaceous gland development. Maturation of the gland, including changes in its pigmentation and the onset of sexual dimorphism, is discussed in relation to pertinent literature.
Electron microscopy of oligodendrocytes in normal rat cerebrum
Authors: Kruger Lawrence , Maxwell David S.
Published: February 2005

Electron microscopic examination of rat cerebral gray and white matter following formaldehyde or glutaraldehyde vascular perfusion reveals distinctive morphological features for identification of oligodendrocytes. These elements are situated as satellites of neurons (perikarya, dendrites and axons), and display a wide range of nuclear and cytoplasmic densities which tend to parallel each other. Cytoplasmic density appears to be an uncertain criterion for neuroglial identification, but oligodendrocytes are recognizable by the following distinctive features: large quantities of free ribosomes or ribosomal rosettes, numerous nuclear pores and light patches of otherwise dense chromatin adjacent to the pores, extensive cytoplasmic microtubules, absence of broad processes seen in other cerebral elements but presence of numerous fine processes which can occasionally be traced to form the outer mesaxon of myelin sheaths, absence of glycogen and fine gliofibrils uniquely present in astrocytes, and the usual presence of thin rims of perinuclear cytoplasm frequently associated with large dilatations of the nuclear cleft. Arguments are adduced for rejecting the identification of “dark” glial elements as microglia. The relation of oligodendrocytes to myelin and the functional significance of the wide spectrum in cytoplasmic density are considered in relation to the synthetic demands of adjacent neurons.
Cytological changes in hepatic and reticuloendothelial cells in rabbit liver following gonadectomy
Authors: Nathaniel Doris R. , Nathaniel Edward J. H.
Published: February 2005

Male rabbits of the New Zealand strain were castrated and sacrificed after two, four and six weeks. The animals were maintained on normal diet ad libitum. Alterations in hepatic and reticuloendothelial cells were studied with the electron microscope. The response of the hepatic cell was as follows: The most significant change during the second week was a considerable increase in agranular reticulum which was concentrated along the cell borders as well as within the cells. It was associated with glycogen particles. Accumulation of glycogen was progressive from the second week onward. There was a decrease in the smooth surfaced reticulum as the glycogen content increased. It is suggested that the agranular reticulum is related to glycogen metabolism. An increase in lipids was also present. It is observed that gonadectomy has induced an increase in glycogen and lipid content of the cell. In addition, the nucleus showed a moderate condensation of chromatin along the inner margin. There was a slight increase in the rough surfaced endoplasmic reticulum. Castration also produced changes in the Kupffer cell. This was characterized by the shortening of the cell processes resulting in reduction in cell size. There were fewer inclusions within the cell.
The fine structure of testicular interstitial cells in mice
Authors: Christensen A. Kent , Fawcett Don W.
Published: February 2005

The testicular interstitial cells of mice contain an abundant agranular endoplasmic reticulum occurring as a network of interconnected tubules. Unusual features of the reticulum are occasional extensive whorls of concentric membranes and the occurrence of bundles of parallel double‐walled tubules. The mitochondria have tubular cristae and are occasionally very large.

In contrast to the interstitial cells of other species that have been described, the mouse interstitial cells show a segregation of the cytoplasm into areas of dense agranular reticulum and other areas where the agranular reticulum is relatively sparse. The latter areas contain scattered cistenae of granular reticulum, many free ribosomes in clusters, mitochondria, lipid droplets and small granules. The mitochondria and lipid droplets are often encircled by cisternae of the reticulum.

Biochemical evidence from other laboratories, taken with the present results, indicates that the membranes of the endoplasmic reticulum in mouse interstitial cells are the site of the enzymes that mediate the synthesis of testosterone from progesterone. There is also an indication that cholesterol biosynthesis is associated with the agranular reticulum. The membranes of the agranular reticulum may also serve as a reservoir for the storage of cholesterol.
Metrial gland and other glycogen containing cells in the mouse uterus following mating and through implantation of the embryo
Authors: Smith Lois Jean
Published: February 2005

Mouse uteri and embryos from 12 hours to seven days after mating were examined for RNA and glycogen following specific histochemical staining. Because of their greater basophilia, calls present throughout the endometrium which seem to be metrial gland cell precursors could be distinguished as early as two and three‐quarter days. At this time, the uterus is just beginning to undergo “sensitization to decidualization.” By seven days, these precursor cells and metrial gland cells proper have disappeared from all regions of the endometrium except that of the future decidua basalis. Glycogen is present in cells which may be the metrial gland cell precursors, plasma cells and polymorphonuclear leucocytes as well as in the lumens and cells of the uterine glands at three and one‐half days. Between four and one‐fourth and five and one‐half days, glycogen is found in the primary decidual zone. By six days, there is a heavy deposit in the “glycogenic areas.” At seven days, many of the metrial gland cells in the future decidua basalis are PAS‐positive. These findings are discussed and the possible origin of the metrial gland cells from a cell of the lymphocytic series is suggested.
The topographic anatomy of the muscles, nerves, and arteries of the bovine female perineum
Authors: Habel Robert E.
Published: February 2005

The perineal muscles and fasciae are described and illustrated, and the diaphragma urogenitalis, components of m. sphincter urethrae, and m. ischio‐cavernosus are described for the first time in the cow.

The nerves of the pudendal plexus are discussed comparatively with the object of suggesting appropriate names based on their homology to the condition in other animals and man. The rami musculares to m. levator ani and m. coccygeus may originate from nn. sacrales 3 et 4, or n. pudendus, or n. rectalis caudalis. The combination of rami musculares with n. rectalis caudalis was formerly called by veterinary anatomists n. hemorrhoidalis medius, a term which should be abandoned because it is not listed in Nomina anatomica, and because it has also been applied to n. splanchnicus pelvinus in the horse. N. pudendus is large and its rami cutanei supply regio femoris caudalis as well as regio perinealis. It also gives rise to n. perinealis profundus, which supplies the genital muscles. The pudendal nerve ends by dividing into ramus mammarius and n. dorsalis clitoridis. There may be one or two nn. rectales caudales. They supply m. sphincter ani externus and adjacent parts of m. levator ani and the genital muscles.

The distribution of arteria urogenitalis (vaginalis) and a. pudenda interna are described and illustrated.
Effects of pinealectomy in the newborn female rat
Authors: Wragg Laurence E.
Published: February 2005

That pinealectomy in the rat is followed by ovarian hypertrophy is an assumption which is rather widely accepted and which is fundamental to much contemporary pineal research. Nevertheless an analysis of the alleged supporting literature shows it to be surprisingly weak and limited to animals operated at three to four weeks of age. In several mammals young pineals have been shown to equal or exceed older pineals in certain metabolic activities, but the effect of pineal ablation in the newborn rat is unknown. This report is based on Holtzman female rats pinealectomized at three days, and sacrificed at 60 days of age. The animals comprise a littermate series of eight normal, eight sham operated and eight pinealectomized; and a non littermate series of 18 normal, 17 sham operated, and ten pinealectomized rats. Pinealectomy was proved complete by microscopy of serial sections. Pinealectomized animals in both series did not differ from normals in the weight of the body, ovary, uterus, adrenal, or hypophysis; nor was there a difference in time of vaginal opening, estrous cycle, or 24 hour urinary sodium and potassium output.
The fine structure of the zona glomerulosa and the zona fasciculata of the adrenal cortex of the opossum
Authors: Long John A. , Jones Albert L.
Published: February 2005

The normal fine structure of the zona glomerulosa and the zona fasciculata of the opossum is described, with emphasis on the structure of the smooth surfaced endoplasmic reticulum (SER) and mitochondria. The cells of the zona glomerulosa are characterized by the presence of numerous rod‐shaped mitochondria with shelf‐like cristae, small amounts of tubular SER and moderate amounts of rough surfaced endoplasmic reticulum. The cells of the zona fasciculata possess large quantities of SER, spherical mitochondria with tubular cristae and a few profiles of rough surfaced reticulum. A Golgi apparatus is present in cells of both zones as are coated vesicles, coated invaginations of the plasmalemma, lysosomes and lipid droplets. It is concluded that the tubular SER seen in electron micrographs corresponds closely to the form of this membrane system found in the living cell. The functional significance of the associations observed among lipid droplets, mitochondria and SER are discussed.
The effect of pregnancy on the elastic membranes of mesometrial arteries in the guinea pig
Authors: Albert Ernest N.
Published: February 2005

Mesometrial arteries were obtained at various stages from adult virgin and primiparous guinea pigs beginning at pregnancy and ending at 40 days post‐partum. The tissues were processed routinely and then stained with hematoxylin and eosin, and various elastic tissue stains. Picro‐indigo‐carmine and Van Gieson were used as counterstains.

It was found that during the early stages of pregnancy the subendothelial cells of mesometrial arteries began to proliferate and the internal elastic membrane showed signs of fragmentation. By term the subendothelial cells formed a several layer thick cushion and the elastic fibers were virtually absent. About 22 days post‐partum the subendothelial cells had disappeared and a new internal elastic membrane had formed. These changes are found mainly in the placental mesometrial arteries and to a lesser degree in the peripheral ones. Guinea pigs with unilateral pregnancies exhibited the above changes only on the side of the pregnant horn. It is suggested that the above changes are due to pregnancy and that local hormones elaborated by the placenta may be largely responsible for the alterations in the mesometrial arteries during pregnancy.
The fine structure of compensatory growth in the rat kidney after unilateral nephrectomy
Authors: Anderson Winston A.
Published: February 2005

The structural changes in the nephrons of the rat kidney during compensatory growth were observed for 96 hours following unilateral nephrectomy. Hypertrophy of tubular epithelial cells involves dilation of the cisternae of rough endoplasmic reticulum, proliferation of Golgi membranes and agranular reticulum, and increase in number of cytoplasmic ribosomes. The appearance of absorption droplets and microtubules, that are polarized along the cell axis, coincides with maximal hypertrophy of proximal tubule cells. Premitotic dedifferentiation of these cells involves flattening of the basal infoldings of the plasmalemma, decrease in number and disorientation of mitochondria, loss of apical compartments, and the reduction in number of microvilli. Cilia appear on the apical borders of some cells. Bundles of 30–50 Å filaments occupy the cytoplasm at the base of proximal tubule cells.

In distal tubule cells that are undergoing mitosis, numerous mitochondria remain intimately associated with infoldings of the basal plasmalemma. This persistence of the differentiated basal region prevents complete cell division, and binucleate and multinucleate cells arise as a result of failure of cytoplasmic cleavage after normal karyokinesis. During mitosis, the chromosomes and apical vesicles are restricted to organelle‐free masses of cytoplasm that project into the lumen.

In collecting tubules, both intercalated and lining cells undergo mitosis during compensatory growth. By 72 hours, a less differentiated cell type, that is active mitotically, appears in the cortical portion of collecting tubules. The number of binucleate epithelial cells increases in the compensating kidney tubules. Unilateral nephrectomy also induces distinct alterations in the fine structure of the glomerulus and the papilla of the contralateral organ.
Some aspects of spermiogenesis in a lizard
Authors: Clark Allen W.
Published: February 2005

Spermatids of the American chameleon Anolis carolinensis, have been examined with the electron microscope during the period from the first appearance of caudal sheath microtubules to the stage of differentiation just before the caudal sheath disappears. The caudal sheath microtubles are arranged initially in the form of a helix with a very low pitch. As the condensation of the chromatin and the elongation of the nucleus proceed, the caudal sheath helix unwinds. Shortly before the caudal sheath disappears, the sheath microtubles are oriented parallel to the longitudinal axis of the nucleus and the sheath resembles those found in other vertebrate spermatids. Assuming that the caudal sheath is functionally related in some way to the changes that occur in the nucleus, it is proposed that the unusual arrangement of the caudal sheath in A. carolinensis spermatids is a device to avoid a large excess of microtubules clustered around the nucleus at the end of nuclear elongation.
An ultrastructural study of opaque cytoplasmic inclusions induced by triparanol treatment
Authors: Chen I‐Li , Yates Robert D.
Published: February 2005

The administration of triparanol caused an hypertrophy of smooth membranes and the occurrence of numerous cytoplasmic bodies in smooth muscle fibers and parasympathetic ganglion cells in the myenteric plexus of the hamster ileum. The hypertrophied membranes were more evident in the early stages of treatment when the cytoplasmic bodies were relatively few in number. The cytoplasmic bodies were tentatively divided into four types as follows: whorls of membranes (type I), labyrinthine aggregates of smooth membranes (type II), dense bodies with a reticular internal structure (type III) and crystalline bodies showing a regular lattice pattern (type IV). There were also many intermediate types of cytoplasmic bodies which exhibited more than one characteristic of the types mentioned above. The relative numbers of the cytoplasmic bodies seemed to be increased in the order of type I (or type II), type III, and type IV in proportion to the period of treatment. It is suggested that type IV cytoplasmic bodies are formed through the stages of type I (or type II) and type III, and that types I, II, and III in turn, form from hypertrophied smooth membranes. The formation of crystalline bodies from hypertrophied membranes may represent the inclusion of cytoplasmic organelles into autophagic vacuoles (lysis). After certain degrees of lysis, more resistant components of the hypertrophied membranes remain as residues. These residues, rich in phospholipids, are probably represented as crystalline bodies.
Tissue binding of tritiated norepinephrine in pigmented nuclei of human brain
Authors: Ishii Tsuyoshi , Friede Reinhard L.
Published: February 2005

Regional binding of norepinephrine to tissue structures occurs in sections of brain tissue incubated in vitro with tritiated norepinephrine, followed by radioautography. The binding probably represents one of the mechanisms involved in the uptake and storage of catecholamines by nerve cells. Applying this method to a study of human brains showed excessively strong binding of norepinephrine at the surface membranes of pigmented nerve cells in the substantia nigra, nucleus coeruleus, nucleus dorsalis vagi, and others. Such excessive binding was not found in nonpigmented nuclei in the human brain nor in rat brain. The arrangement of sites of binding at the cell membranes strongly suggested synaptic endings. Melanin pigmentation of nerve cells may be related to the amount of catecholamine‐containing synapses at the surface of the neurons.
The fine structure of corpora lutea in ovarian transplants of mice following luteotrophin stimulation
Authors: Crisp Thomas M. , Browning Henry C.
Published: February 2005

Lutein cells from non‐functional white corpora lutea of ovulation and functional hyperemic corpora following exogenous luteotrophin stimulation were studied in ovarian isotransplants of the mouse with the aid of the light and electron microscope. Luteal tissue of white corpora consisted of small parenchymal cells, some intercellular material and a meager vascular bed. Luteal tissue from hyperemic corpora lutea possessed a rich sinusoidal plexus which supplied the hypertrophied lutein cells. At the fine structural level, lutein cells from functional, hyperemic corpora were distinguished from non‐functional lutein cells in having a reduced lipid content, well‐developed Golgi complex, abundant tubulo‐vesicular elements of agranular and granular endoplasmic reticulum, non‐motile cilia and a more elaborate folding of the cell membrane into microvillous projections bordering the subendothelial space. The functional significance of these morphological changes of luteal tissue in response to luteotrophin was discussed and correlated with recent biochemical findings of steroidogenic tissue. It was concluded that the presence of luteotrophin following luteinization in mouse ovarian transplants results in numerous morphological changes of luteal tissue which are indicative of progesterone synthesis and secretion.
A blood‐brain barrier to peroxidase in capillaries surrounded by perivascular spaces
Authors: Bodenheimer T. S. , Brightman M. W.
Published: February 2005

Some investigators have hypothesized that the absence of a blood‐brain barrier in specialized regions of the mammalian central nervous system is related to the occurrence of a pericapillary connective tissue space that can accommodate more substance than the usual narrow extracellular space in the remainder of the cerebral parenchyma. The capillaries of the urodele brain are well suited to test this hypothesis. All of the cerebral capillaries examined electron‐microscopically in Necturus maculosus are surrounded by a collagen‐containing space, about 0.5 m̈ wide, which is delimited by an endothelial and a glial basement membrane. In Ambystoma tigrinum, some capillaries have perivascular spaces whereas others are surrounded by a single basement membrane shared by endothelium and glia and therefore resemble mammalian vessels exhibiting barrier phenomena. In both Necturus and Ambystoma, horseradish peroxidase administered intravenously one‐half to two hours before fixation did not cross the brain capillary endothelium. The bulk of the protein remained in the vessel lumen, although some was incorporated by membrane‐bound inclusions within the endothelium, and none ever reached the perivascular basement membrane, space or parenchyma. The amphibian cerebral endothelium is, like the mammalian endothelium, the locus for the barrier to the entry of peroxidase from blood to parenchyma. Thus, the mere occurrence of a pericapillary space is not necessarily coincident with the absence of a blood‐brain barrier.
Fine structure of anchoring villi of the human placenta
Authors: Enders Allen C.
Published: February 2005

Anchoring villi from the first trimester, early second trimester, and term were examined with the electron microscope. It was found that the small anchoring villi of the third and fourth month were particularly informative, since at this stage the cytotrophoblast is still proliferating, yet these cells form a compact discoidal region at the surface of the basal plate. Transitions from relatively undifferentiated cytotrophoblast cells adjacent to the stroma of the villus to large isolated cells surrounded by fibrinoid could readily be followed. These highly differentiated cytotrophoblast cells were found to have extensive regions of fine filaments, in addition to their pronounced endoplasmic reticulum, and were designated fibrous cytotrophoblast cells. The nature of the frequently incomplete epithelium covering anchoring villi at term was described, and some of the functions of the cytotrophoblast are discussed in relation to the observations of their fine structure.
The relationship between the dimensions of the fibres and the number of nuclei during restricted growth, degrowth and compensatory growth of skeletal muscle
Authors: Moss F. P.
Published: February 2005

During unrestricted growth of the pectoral muscle of chickens, the mean cross‐sectional area of the fibres increased in proporiton to the total number of nuclei and in proportion to the two thirds power of the weight of the muscle. Continuous restricted feeding from 0 day, which limited the weight of the muscle at 16 days to 44% or 69% of that of chickens fed ad libitum, did not affect these relationships.

A sudden restriction of feed from eight days of age retarded growth of the muscle to approximately 70% of the weight of the controls at 16 days. It did not affect the relationship between the number of nuclei and the fibre cross‐sectional area, both of which were also limited to about 70% of those of the controls; but it did disrupt the relationship of these two variates to the weight of the muscle. Subsequent ad libitum feeding caused compensatory growth and restored the relationship.

Starvation or severe undernutrition for a few days, which reduced weight of the muscle and the fibre cross‐sectional area by approximately 25%, caused no loss of nuclei, thereby disrupting both relationships. Subsequent ad libitum feeding initially caused an increase of muscle weight and fibre cross‐sectional area but no increase in the number of nuclei. This restored the relationships, which were then maintained during subsequent compensatory growth.
Ultrastructure of the lung of the goose and its lining of surface material
Authors: Lambson Roger O. , Cohn Jerome E.
Published: February 2005

As the primary bronchus passes through the goose lung it gives rise to two sets of secondary bronchi. One set is located on the dorsal surface of the lung and the other on the ventral surface. These two sets of bronchi are connected by numerous parabronchi which run parallel to one another through the lung. Each parabronchus is the center of and supplies air to a cylindrical lung lobule. Numerous outpocketings of the parabronchial wall, which are called atria, connect with the finest air spaces of the lung parenchyma.

The epithelium lining the parabronchi is continuous with flattened epithelial cells which line the atria and the finest air spaces. The air‐blood barrier is composed of endothelium, a basal lamina, an attenuated pulmonary epithelium, and an 80–120 Å thick osmiophilic layer which covers the attenuated epithelium. Multiple layers of a unit‐membrane‐like material similar to that lining each fine air space is found covering and invaginating the epithelial cells lining the atria and parabronchi. Within many of these atrial and parabronchial cells, laminated osmiophilic material is found within cisternae of rough‐surfaced endoplasmic reticulum, and inclusion bodies which may contain both laminations and a granular matrix similar to that within adjacent Golgi vesicles. It is suggested that the endoplasmic reticulum may be involved in the synthesis of the surface material found lining the goose lung.
Renal morphology of the english sole (parophrys vetulus)
Authors: Bulger Ruth Ellen , Trump Benjamin F.
Published: February 2005

The nephron of the English sole, Parophrys vetulus, is composed of the following regions: a renal corpuscle with few capillary loops and an extensive mesangial area with mesangial cell processes insinuated between endothelium and podocyte basement membrane; a ciliated neck segment with mucous‐containing cells; the first major brush border segment with a broad vacuolated apical zone most closely resembling the mammalian proximal convoluted tubule; a second major brush border segment with the tallest most eosinophilic cells; a gradual transition to a third major brush border segment with lower, more basophilic cells; no distal convolution and a collecting tubule which empties into a collecting duct system. Granulated cells in the arteriolar media appeared to be modified smooth muscle cells.
The ultrastructure of the crevicular epithelium of cat gingiva
Authors: Gavin J. B.
Published: February 2005

The ultrastructure of the crevicular epithelium of clinically healthy cat gingiva was similar to that of other non‐keratinizing oral epithelia. However, it differed in that the intercellular spaces were wide and extended as a continuous network from the basal lamina to the epithelial surface. Basal cells contained numerous mitochondria, Golgi apparatus, free ribosomes and a fine feltwork of evenly distributed tonofilaments. Hemidesmosomes were present in relation to the basal lamina. Cells in the intermediate layers showed a decrease in the number of organelles and an increase in concentration of tonofilaments, Superficial cells were further flattened and the remaining organelles commonly showed degenerative changes. Epithelial cells showed prominent microvilli extending into the intercellular spaces. Some of these formed desmosomes with similar processes of adjacent cells. Occasional randomly distributed tight junctions were also observed. Inactive basal melanocytes, more superficial Langerhans cells and leucocytes were seen between epithelial cells. The great majority of leucocytes were neutrophils and many of these ruptured as they approached the epithelial surface scattering their specific granules into the intercellular spaces. These findings are discussed in relation to the peculiar permeability of the gingival crevicular region of the oral mucosa to tissue fluid and leucocytes.
Cortisone‐induced hypertension and cardiovascular lesions in mice
Authors: Clarke Thomas D. , Ashburn Allen D. , Williams W. Lane
Published: February 2005

Daily subcutaneous injections of cortisone acetate (0.5, 1.5 or 2.5 mg) were given to three groups of mice for seven consecutive days. Daily systolic blood pressures of the anesthetized mice were obtained by adapting the method of Friedman and Freed ('49). The maximal arterial pressure increase for the 0.5, 1.5 and 2.5 mg groups was 22%, 31% and 41% respectively. This supports the conclusion that cortisone produces hypertension in mice when administered in large doses. Mural hyalinization, vacuolization and cellular proliferation of coronary arteries were greatest in the 0.5 mg group. The highest incidence of myocardial necrosis, 56%, was in the group receiving 2.5 mg of cortisone daily. The frequency and severity of myocardial and renal cortical necrosis were directly related to the size of the cortisone dose. Adrenal medullary vacuolization and lipid infiltration of the liver were common in all experimental groups.
Light and electron microscopic observations on the spleen and the splenic leukocytes of the newt triturus cristatus
Authors: Tooze J. , Davies H. G.
Published: February 2005

The newt spleen has an outer region, the red pulp, that consists of reticular fibres, reticular cells, and fixed macrophages forming a framework within which erythropoiesis occurs, and an inner region, the white pulp, consisting of a reticular framework containing predominantly lymphocytes. The fine structure of the following leucocytes, namely lymphoid cells, reticular cells, macrophage, haemocytoblasts, plasma cells and neutrophilic, basophilic and eosinophilic granulocytes is, in general, similar to that of the corresponding mammalian blood cells. However, in contrast, all the nuclei contain large numbers of interchromatin granules and a differentiated region termed the nuclear light‐staining zone because of its electron‐scattering properties. Furthermore the specific granules of the eosinophilic granulocytes are structureless whereas those of the basophilic granulocyte have crystalline regions. The structure and distribution of the granular, fibrillar, tubular and vesicular components of the cytoplasm of each cell type is described.
Lymphopoiesis and lymph node histogenesis in the embryonic and neonatal rabbit
Authors: Hostetler Jeptha R. , Ackerman G. Adolph
Published: February 2005

The thymus represents the first lymphocytic organ to exhibit lymphopoietic activity in the fetal rabbit with lymphoblastic transformation beginning by 17 days of gestation, and lymphocytes appearing by 18 days, one to two days before vascularization. Lymphocytes are first evident in lymph nodes at 18 days of fetal development, in the spleen on the twenty‐third day, and in the appendix just prior to birth.

Medium‐sized lymphocytes and rare blast‐like cells represent the first lymphocytic cells found in the lymph node anlage. Both of these cell forms appear simultaneously and are distributed randomly. Lymphocytes remain relatively sparse increasing gradually in number until several days prior to birth when their numbers increase rapidly. Coincident with the augmentation in lymphocyte population, lymphocytes tend to cluster near the vascular channels, and are present within the lumina and walls of the smaller veins in the node. Morphological gradations between mesenchymal cells and medium‐sized lymphocytes provide suggestive evidence that the initial population of lymphocytes within the node arise by the direct transformation of the stromal cells into medium‐sized lymphocytes. Less frequently, deeply basophilic blast‐like cells may provide an intermediate stage in lymphocyte differentiation. These cells differ from typical lymphoblasts because of their smaller size and irregular cellular contour.

It is postulated that the initial population of lymphocytes formed in the lymph node anlage is derived from the transformation of mesenchymal cells and subsequent homoplastic lymphocyte proliferation and that during later fetal life this population of lymphocytes is complemented by the colonization and proliferation of blood‐borne lymphocytes.
Differentiation of interstitial cells and sertoli cells in fetal guinea pig testes
Authors: Black Virginia H. , Christensen A. Kent
Published: February 2005

Smooth endoplasmic reticulum appears in interstitial cells and Sertoli cells of 22–24d testes of fetal guinea pigs before the beginning of morphological differentiation of the male reproductive tract at 29d (Price et al., '67), and before the appearance of demonstrable 3β‐hydroxysteroid dehydrogenase, an enzyme important in steroid biosynthesis, in the interstitial cells at 29d (Ortiz et al., '66). This enzyme has not yet been demonstrated in the Sertoli cells.

The smooth reticulum of the interstitial cells increases in amount, filling the cells with tubules by 27d, and later forming some fenestrated cisternae which are occasionally seen in whorls. In Sertoli cells, the tubular reticulum shows signs of degeneration at 26d. After this time the cisternal endoplasmic reticulum in these cells increases in amount and by 45d is predominantly smooth‐surfaced. Yet it is never as prominent as the smooth reticulum of the interstitial cells.

Scattered clusters of ribosomes or polyribosomes are seen on the surface of the tubular reticulum of these differentiating cells. These polyribosomes become more widely spaced as the smooth‐surfaced areas increase and may be associated with the production of smooth membranes.

Smooth endoplasmic reticulum is known to play a role in the production of steroid hormones, and therefore the extensive development of smooth reticulum in fetal interstitial cells is consistent with experimental evidence that implicates these cells as the chief source of steroid hormones governing male reproductive tract differentiation.