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Baker, Burton L.; Drummond, Thérése
doi: 10.1002/aja.1001340402pmid: 4114838
The cellular origins of corticotropin and melanotropin were studied by observing the response of the rat hypophysis to adrenalectomy and cortisol administration when stained immunochemically with peroxidase‐labeled antibody following application of antiserums to β1–24‐corticotropin, βP17–39‐corticotropin, human β‐melanotropin, and α‐melanotropin. The presence of corticotropin in the pars intermedia is indicated since this lobe, in addition to corticotropic cells of the pars distalis, stained with antiserum to βP17–39‐corticotropin. However, the concentration of corticotropin is less in the pars intermedia than in corticotropic cells since at higher dilutions of antiserum the latter cells stained intensely while the pars intermedia was unstained. Also, corticotropic cells exhibited striking hypertrophy after adrenalectomy and regression after cortisol administration, while morphological and tinctorial properties of the pars intermedia were minimally altered. These observations suggest that the pars distalis is primarily responsible for supplying the corticotropin required to meet the changing requirements of the body.
doi: 10.1002/aja.1001340403pmid: 5047596
Several studies have indicated that morula‐staged t12/t12 mouse embryos are deficient in nucleolar RNA synthesis and that this deficiency may be a causal factor of death. The present investigation was undertaken to see if decreased RNA synthesis in t12/t12 embryos occurs prior or subsequent to developmental arrest. In this study, embryos obtained from +/t12 inter se matings were labeled with 3H‐5‐uridine at specific cleavage stages and then subjected to high resolution autoradiographic study. These staged embryos were either examined immediately following labeling or were reincubated in nonradioactive medium and then studied. Comparisons between autoradiographs of the phenotypically mutant embryos and their phenotypically wild‐type littermates revealed no significant difference between these two groups in either the amount or distribution of the incorporated RNA precursor at any cleavage stage. Late morula t12/t12 embryos, prior to the appearance of advanced degenerate changes following developmental arrest, did not differ significantly in their labeling patterns from the labeling patterns of phenotypically wild‐type late morula. These findings indicate that the initial effect of the t12/t12 genome is not on rRNA synthesis. The incorporation of the labeled precursor into the intranuclear fibrillo‐granular bodies which characterize t12 homozygotes, was also studied.
doi: 10.1002/aja.1001340404pmid: 5047597
Terminating arterial vessels, the structure of sinuses and cords, and the passage of cells through the sinus wall in the red pulp of human spleen were studied. All terminating arterial capillaries arterial capillaries observed opened into cords. The distance between terminating arterial capillaries and sinuses varied. Macrophages were commonly present at arterial terminations. Arterial capillary endothelium contained filaments about 80 Å in diameter. Blood cells were frequently present in the capillary lumen or in passage through the capillary wall into cords. Endothelial cells of sinuses contained three distinctive structures: loosely organized cytoplasmic filaments, tightly organized finer filaments, and micropinocytotic vesicles. Many micropinocytotic vesicles about 0.1 μ in diameter were present just beneath the plasma membrane of the lateral and luminal sides of sinus endothelial cells and a few at the basal aspect. Loosely organized filaments about 80 Å in diameter ran parallel to the longitudinal axis of the sinus endothelium. The finer filaments about 30–50 Å in diameter were tightly organized as filamentous bands and present basally. The filaments of the bands appeared inserted upon the plasma membrane. They were also present in the cordal reticular cells and terminating arterial capillaries. Free cells were frequently present in passage through the slits of the sinus wall. There were no preformed or fixed apertures in the sinus wall. The basement membrane and reticular fibers were completely covered by the endothelial cells and/or cordal reticular cells.
Nunez, Eladio A.; Whalen, Joseph P.; Krook, Lennart
doi: 10.1002/aja.1001340405pmid: 5047598
Cyclical ultrastructural changes in chief cells of the bat parathyroid during hibernation are described. The morphology indicates that the cells increase in activity at the start of hibernation and decrease in activity at the end. During early hibernation, the main alterations are an increase in granular endoplasmic reticulum, an increase in the number of prosecretory granules associated with the Golgi apparatus, an increase in the number of mature secretory granules, and the appearance of numerous, large cytoplasmic lipid droplets. An unusual finding is that the lipid droplets are preferentially associated with mitochondria and glycogen deposits. At this time there is also an increase in the size of intercellular spaces and the concentration of secretory granules near the plasma membrane. By late hibernation, however, there is a marked reduction in the amount of granular endoplasmic reticulum, fewer mitochondria, inconspicuous Golgi apparatuses, and a reduction in the size of intercellular spaces. In addition, lipid droplets are absent. These observations are discussed in relation to the cyclic secretory changes which occur in bat parafollicular cells and in bone during hibernation.
doi: 10.1002/aja.1001340406pmid: 5047599
Most avian skeletal muscles have their triads at the A‐I junction, and there is a complex sarcoplasmic reticulum in the Z‐line region because of the architectural arrangement of two triads in one sarcomere. The sarcotubular system in the pigeon serratus superficialis metapatagialis muscle was examined with the electron microscope. In these muscles the t‐tubules open to the extra‐cellular space, and there is an indication that mitochondria may connect to the sarcotubular system. The elements of the sarcoplasmic reticulum between two triads of a single sarcomere is similar to that in the frog, and consists of the triads, intermediate cisternae, longitudinal tubules, and fenestrated collar. In the portion of the sarcoplasmic reticulum between triads of adjacent sarcomeres, the triads are coupled. This is brought about by triads extending from one sarcomere to the next and by the connection of the reticulum between triads of adjacent sarcomeres. Some of the tubules making up the Z‐line reticulum have a fenestrated appearance, similar to the fenestrated collar.
doi: 10.1002/aja.1001340407pmid: 5047600
The case of a full term, stillborn infant with herniation of the viscera through a so‐called left Bochdalek foramen is analyzed. Graphic and wax reconstructions of the uninflated left lung record the degree of differentiation and the histologic appearance of the atelectatic parenchyma. To this is appended a discussion of the probable sequence of events during gestation; and an explanation of why such hernias usually protrude into the left, and not the right pleural cavity.
Dementi, Patricia L.; Burke, Jack D.
doi: 10.1002/aja.1001340408pmid: 5065394
Oxygen‐hemoglobin affinity curves determined spectrophotometrically at 26± 1° C on phosphate‐buffered hemoglobin solutions of 9 armadillos yielded a mean P50 value of 10.1 mm Hg at pH 7.4 and 18.4 mm Hg at pH 6.8. For the 18 curves determined simultaneously at both pH's the mean calculated magnitude of the Bohr effect was ϕ = − 0.43. These values indicate a moderately low P50 (high oxyhemoglobin affinity) and small Bohr effect, consistent with the low metabolic rate of Dasypus novemcinctus. Indicative of increased tolerance to blood acid by‐products, a small value would be advantageous to the armadillo in its adaptation to intensive anerobic energy production. A major and a more slowly moving minor hemoglobin fraction was confirmed by vertical starch‐gel electrophoresis using borate buffer at pH 8.7 and benzidine staining. Transmission curves on oxyhemoglobin had an α peak at 578 mμ and a β peak at 543 mμ.
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