bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivesicular bodies and related structures of the syncytiotrophoblast of human term placenta
Authors: Martin B. J. , Spicer S. S. 
Published: February 2005

AbstractMultivesicular bodies and related structures of the syncytiotrophoblast of human term placenta have been studied ultrastructurally and cytochemically. Circular profiles of vesicles termed pre–multivesicular bodies (pre‐mvb's) were observed often near Golgi complexes. Multivesicular bodies (mvb's) with electron lucent matrices (L‐mvb's), mvb's with electron dense matrices (D‐mvb's), and dense bodies were also prevalent organelles of the syncytium. These organelles all exhibited dialyzed iron reactivity and staining characteristics suggesting that the organelles were related. Material within Golgi saccules, Golgi vesicles, vesicles of pre‐mvb's, and vesicles of mvb's were all reactive with osmium zinc iodide (PZI). This OZI reactivity further indicated a relationship between the organelles. The matrix of the mvb's exhibited variable reactivity for acid phosphatase (AcPase) but such activity was not encountered in Golgi elements of syncytiotrophoblast. It is suggested that the mvb's of human term placental syncytium are likely formed by aggregation of vesicles of Golgi origin into pre‐mvb's, that the pre‐mvb's are then capable of transforming into L‐mvb's, D‐mvb's, and finally into dense (residual) bodies. It is also suggested that mvb's may function in the selective hydrolysis and transport of endocytosed proteins, including globulins. Additional bodies with intense acid phosphatase activity were designated elongate bodies. Other Distinctive organelles designated dense cored spheroids were occasionally observed in the syncytioplasm.
The fine structure of pacemaker cells in the pig renal calices
Authors: Dixon J. S. , Gosling J. A. 
Published: February 2005

AbstractUsing the electron microscope, two types of smooth muscle cell have been recognized in the upper urinary tract of the pig. One type is confined solely to the renal attachment of each minor calix and possesses a number of atypical features. These cells are not grouped into bundles but form a loose meshwork. They frequently branch, are comparatively long with very irregular profiles, and are separated by relatively large amounts of connective tissue although maculae adhaerentes are occasionally observed between neighbouring cells. Dense micronbrils occur in the vicinity of the cells which are surrounded by a partial basal lamina. Groups of axons are seen in the region, many of which contain small dense‐cored vesicles. Within the atypical cells, filaments are loosely packed and accumulations of micropinocytotic vesicles are not observed. These features contrast markedly with those of typical muscle cells in other regions of the upper urinary tract where they form tightly packed bundles unrelated to axon profiles. The typical smooth muscle cells are larger and more regular in outline, are surrounded by a complete basal lamina, possess tightly packed filaments, and contain numerous micropinocytotic vesicles and glycogen particles.Similar modified muscle cells occur in the unicaliceal systems of other species where they are also confined to the proximal end of the urinary tract. It is suggested that the atypical cells are specially adapted to function as spontaneously active “pacemakers” initiating ureteric peristalsis.
The ultrastructural pathology of the rat epididymis after administration of α‐chlorhydrin (U‐5897). I. Effects of a single high dose
Authors: Hoffer Anita P. , Hamilton David W. , Fawcett Don W. 
Published: February 2005

AbstractThe ultrastructural pathology of the initial segment of the rat caput epididymidis was examined after oral administration of a single high dose of the antifertility compound α‐chlorhydrin (U‐5897) at time intervals ranging from two hours to nine days after treatment. At doses in excess of 30 mg/kg this compound produces a lesion specifically localized in the initial segment of the epididymis characterized by sloughing of the epithelium, which leads to obstruction of the lumen of the epididymal duct, spermatocoel and sperm granuloma formation and an ultimate occlusive fibrosis. In rats fed 140 mg/kg of U‐5897 the first effects can be seen as early as two hours after treatment. Within 48 hours after treatment, the lumen of the greater part of the initial segment is filled with degenerating cells and debris which block further passage of sperm along the duct. The present study provides insight into the nature of the early events in the evolution of this epididymal lesion. Possible mechanisms of action of α‐chlorhydrin are discussed.
Changes in distribution of lipid, glucose‐6‐phosphate dehydrogenase and malate enzyme within the liver lobule of the rat during adaptive hyperlipogenesis
Authors: Severson Arlen R. , Hubbard Dorothy D. , Gibson David M. 
Published: February 2005

AbstractFeeding rats a high‐sucrose, fat‐free diet after two days of starvation resulted in an initial accumulation of hepatic lipid and an increased activity of those enzymes which catalyze and support the formation of fatty acids from acetyl precursors. Rats starved for 48 hours were refed a high‐carbohydrate, fat‐free diet for 1, 2, 3, 5, 7 and 14 days. Frozen sections of liver were stained with Oil Red O for lipids. In adjacent sections glucose‐6‐phosphate dehydrogenase (GDH)and malate enzyme (ME) were localized and the relative enzyme activity evaluated. Enlargement and yellowing of the liver were noted after two to three days feeding of the fat‐free diet, but subsequently the liver appeared normal. Oil Red O staining demonstrated a progressive accumulation of lipid from the periportal to the centrilobular area during the first three days of refeeding. After the seventh day on the fat‐free diet, however, the lipid accumulation was less and the distribution appeared similar to that of animals maintained on a balanced diet. A marked increase in both GDH and ME activity was noted throughout the liver lobule after two days on the fat‐free diet. Enzyme activity remained high throughout the lobule during the balance of the experimental period, with maximum activity in the centrilobular area.
An autoradiographic study of the utilization of tritiated uridine by osteoblasts of young mice,
Authors: Singh I. J. , Tonna E. A. 
Published: February 2005

AbstractThe uptake and turnover of 3H‐uridine by periosteal and endosteal osteoblasts were assessed autoradiographically. Five‐week old mice were injected with 5 m̈CI of 3H‐uridine (Sp. Act. 21 Ci/mM) per gram of body weight and killed at intervals varying from 15 minutes to one month post‐injection. Femora were processed histologically and autoradiographs were prepared from 5 m̈m decalcified sections exposed for 36 days. Autoradiographic grains were counted over the nucleus and the cytoplasm of 600 periosteal and 600 endosteal osteoblasts per time period. 3H‐Uridine was initially rapidly incorporated into the nucleus attaining peak activity one hour after injection. Incorporation of label into cytoplasmic RNA was maximum at one to two days. At one month grain counts were at minimum values. The loss was more gradual from the nucleus than from the cytoplasm. At earlier time periods the nucleus showed a higher label than the cytoplasm. At 8 to 16 hours the label was evenly distributed and at later time periods the cytoplasm exhibited a higher grain count. Dia‐physeal periosteal osteoblasts and metaphyseal endosteal osteoblasts differed in both the quantity of label and the rate of utilization. Endosteal cells exhibited almost twice the activity. RNA biosynthesis appears to be significantly higher in endosteal cells than periosteal cells thus reflecting differences in protein synthesis by these two cell compartments.
Ultrastructure of the fetal rat adrenal gland at full‐term and during prolonged gestation
Authors: Thliveris James A. , Connell Reid S. 
Published: February 2005

AbstractThe ultrastructure of the fetal rat adrenal gland is described at full‐term (day 22) and during artificially prolonged gestation (days 23, 24, 25). The latter was achieved by daily subcutaneous injections of seven mg progesterone to gravid females from the twentieth through the twenty‐fourth day. Cortical and medullary cells contained well developed organelles at all stages. Nonetheless, zonation of the gland was not yet distinct. Whereas the zona glomerulosa and zona fasciculata were fairly well delineated, the zona reticularis and medulla were as yet poorly defined. The latter regions were intermingled, and thus collectively referred to as the “zona reticulo‐medullaris.”During prolonged gestation (days 24 and 25 only), many cells of the zona fasciculata and zona reticulo‐medullaris contained dilated smooth endoplasmic reticulum and numerous enlarged mitochondria. Enlarged mitochondria were observed also in medullary cells concurrent with a paucity of catecholamine storage granules. Moreover, meconium staining, which is indicative of fetal stress, was also observed on days 24 and 25. The ultrastructural changes observed were interpreted to be an expression of response by the fetal adrenal gland to fetal stress produced by as yet undetermined factors arising during prolonged gestation.
Fine structure and progesterone concentration in the corpus luteum of the african elephant
Authors: Ogle Thomas F. , Braach Harold H. , Buss Irven O. 
Published: February 2005

AbstractCorpora lutea from one recently post‐partum and six pregnant African elephants (Loxodonta africana) were fixed for electron microscopy. Progesterone concentration was determined for five of these corpora lutea utilizing the competitive protein binding technique.Lutein cell size and progesterone concentration increased from one and two months of pregnancy to a maximum at three months (P < 0.01). After eight months of pregnancy, lutein cell size decreased to two‐month values and luteal progesterone was similar to the one‐month level. Lutein progesterone was very low in a recently post‐partum animal and lutein cell size was minimum. Maximum lutein progesterone was 4.1 ng/mg, much lower than that reported for other mammals.Lutein cell fine structure exhibited characteristics typical of lutein cells from other species but with some variation. Unusual features include peripheral distribution of organelles, large stores of lipid and lipofuscin throughout pregnancy, and mitochondria sparsely populated with lamellar cristae. The data indicate that the corpus luteum of the African elephant has significant but limited steroidogenic capabilities.
Relationship of extracellular matrix vesicles to calcification in normal and healing rachitic epiphyseal cartilage
Authors: Simon David R. , Berman Irwin , Howell David S. 
Published: February 2005

AbstractNucleation sites for mineralization in rat distal femoral epiphyseal cartilage were studied with the electron microscope. Normal, low‐phosphate, vitamin D deficient rachitic, and healing rachitic rats were used.The earliest ultrastructural evidence of mineralization in normal animals was the appearance of crystallites inside extracellular matrix vesicles, located in the longitudinal septa of the maturing cell zone in the epiphyseal apparatus. The crystallites were absent throughout the entire hypertrophic cell zone of the rachitic specimens.The first evidence of mineralization in rachitic animals treated with both phosphate and vitamin D was the presence of crystallites in the extracellular matrix vesicles. These were located in the longitudinal septa of the lower hypertrophic cell zone, near the capillary tufts of the primary spongiosa. Crystallites were first detected by 12 hours after treatment; by 24 to 48 hours, the number of matrix vesicles containing crystallites increased substantially.Treatment of rachitic animals with phosphate alone effected the same results as phosphate and vitamin D combined. Rachitic animals receiving vitamin D alone did not form mineral in the time periods studied.The results of this investigation support the view that the deposition of mineral in mammalian cartilage requires nucleation sites in the extracellular matrix. The findings also are consistent with the hypothesis that membrane‐bounded, extracellular matrix vesicles contain the initiating system for calcification of the rat epiphyseal apparatus.
Transmission electron microscopy of critical point dried tissue after observation in the scanning electron microscope
Authors: Meller Samuel M. , Coppe Michael R. , Ito Susumu , Waterman Robert E. 
Published: February 2005

AbstractEmbryonic and adult rodent tissues were fixed and prepared for scanning electron microscopy by dehydration in ethanol followed by critical point drying with liquid carbon dioxide or Freon 13 (E. I. du Pont de Nemours, Inc.). After coating the dried specimens with evaporated metal, the tissues were studied by scanning microscopy. The same tissues were subsequently embedded in Epon‐Araldite, thin sectioned and examined by transmission electron microscopy. The cytological details in these specimens were comparable to tissues embedded directly, without drying or metal‐coating. With this technique it is possible to identify with greater certainty the structures responsible for surface contours revealed by the scanning electron microscope.
Inhibition of ACTH‐induced differentiation of cortical cells and their mitochondria by corticosterone in tissue culture of fetal rat adrenals
Authors: Kahri Arvi I. 
Published: February 2005

AbstractTissue cultures of fetal rat adrenals were used to study the effects of corticosterone on the ACTH‐induced ultrastructural differentiation of cortical cells and their mitochondria. Corticosterone in dosages of 0.2, 2.0, 5.0, 10, and 20 μg/ml (corresponding to concentrations of 6 × 10−7, 6 × 10−6, 1.5 × 10−5, 3 × 10−5, and 6 × 10−5 molar) was added alone or together with 100 mU/ml of ACTH to the culture medium, daily from the sixteenth day of cultivation up to and including the twenty‐first day. Corticosterone alone induced no ultrastructural changes in cortical cells. Corticosterone in concentrations of 6 × 10−7 to 3 × 10−5 M given with ACTH induced hypertrophy of Golgi apparatus. Corticosterone in concentrations of 6 × 10−5 M inhibited the ACTH‐induced differentiation of cortical cells. However, the nuclear chromatin increased and Golgi apparatus was strikingly hypertrophied. Mitochondria often aggregated adjacent to the nuclear envelope but their ultrastructure remained undifferentiated with tubular or tubulovesicular cristae. Ribosomes appeared as single particles. A marked increase of smooth surfaced endoplasmic reticulum was noted also in cortical cells treated with 6 × 10−5 M of corticosterone.The present observations suggest that corticosterone acts as an intracellular inhibitor in cortical cells. It appears to inhibit cytoplasmic protein synthesis at the ribosomal level and prevents synthesis of cytoplasmic mitochondrial protein synthesis stimulating factor and the latter, in turn, inhibits the activation of mitochondrial protein synthesis. A new model is presented to explain the regulation of growth and secretion in the adrenal cortex.
Resorption of calcified cartilage as seen in Meckel's cartilage of rats
Authors: Savostin‐Asling Irene , Asling C. Willet 
Published: February 2005

AbstractIn rats, a portion of Meckel's cartilage — that lying within the mandible but proximal to the rostral convergence of the bars — gives rise to no definitive structures. It offers especially favorable opportunity to study cartilage resorption. By the eighteenth fetal day it is established as a hyaline cartilage bar, and a thin perichondral bone shell starts to form on its lateral aspect, completing encirclement in the next two days. On day 19 cartilage within this bone shows chondrocyte hypertrophy, lacunar enlargement, and matrix calcification. Osteoclasts open a fenestra laterally in the bone and commence removal of calcified cartilage matrix. The erosion front expands rapidly, moving medially (preceded by cartilage hypertrophy and calcification) and extending proximally and distally along the segment. Chondroclasts (multinucleated cells identical with osteoclasts) dominate the erosion front. Capillaries and various mononucleated cells follow. Bone formation is much delayed except in the most rostral extremity, so that, contrary to the situation in endochondral osteogenesis, one is examining calcified cartilage resorption in uncomplicated form. This resorption, including the perichondral bone shell, is virtually complete by day 21, and intramembranous bony reorganization of the site is in progress at birth.Several features of chondroclasts, including some in dispute or not easily seen in vivo, are well displayed. These include ameboid form with pseudopodial extensions (sometimes filamentous), and fusion of some released chondrocytes with entering chondroclasts. Osteo/chondroclasts are often found in contact with perichondral bone at one extremity and calcified cartilage elsewhere on the same cell. There is evidence that matrix calcification is prerequisite to the chondroclastic activity.
Interaction of the sarcoplasmic reticulum with Z‐lines during myogenesis in amphibian skeletal muscle
Authors: Warren Robert H. 
Published: February 2005

AbstractElectron microscopic examination of developing myofibrils in regenerating skeletal muscle of Rana pipiens tadpole tails reveals that sarcoplasmic reticulum (SR) is in regular and close association with Z‐lines of young sarcomeres before transverse tubules have formed alongside the myofibrils. SR is also associated with M‐lines of young sarcomeres but on a less regular basis than with Z‐lines. Counts of the number of contact sites of SR with Z‐lines, M‐lines and combined A‐ and I‐bands of longitudinally sectioned sarcomeres of young myofibrils confirms the visual impression that the SR associates with a relatively much greater frequency with Z‐lines and M‐lines than with other regions of the sarcomere. This suggests the formation of a specific bond between SR and Z‐ and M‐lines.Serial transverse sections of developing myofibrils were examined in order to determine whether Z‐lines displayed SR association at all stages in their formation. Of fifty discrete Z‐lines that were examined, only four smaller Z‐lines appeared to lack SR association. An examination of a comparable number of more diffuse Z‐bodies representing an earlier stage of Z‐line formation suggests that no more than one‐half of these Z‐bodies were accompanied by SR. These observations support the conclusion that SR does not initiate formation of Z‐line precursor elements, but rather associates with Z‐lines as they condense from more diffuse Z‐bodies.
Demonstration of bile canaliculi by an immunofluorescent staining technique
Authors: Armstrong Ernest M. , Macsween Roderick N. M. 
Published: February 2005

AbstractUsing an indirect immunofluorescent technique sera from a group of patients suffering from a variety of liver diseases have been shown to contain an antibody which will specifically stain the bile canaliculi of a wide variety of mammals, birds and amphibia. It is suggested that this method is an effective alternative to the methods presently available for demonstration of bile canaliculi.
Effect of posterior pituitary powder on the mitotic activity of the zona glomerulosa of the adrenal glands in intact and hypophysectomized rats: A preliminary observation
Authors: Isler H. 
Published: February 2005

AbstractInjections of posterior pituitary powder induced a significant stimulation of mitotic activity in the zona glomerulosa of intact and hypophysectomized rats. Hypophysectomy depressed this activity. The effect of the powder may be due to the presence of vasopressin.
Autoradiographic distribution of collagen loss in skin grafts
Authors: Zika Jocelyn M. , Rudolph Ross , Klein Leroy 
Published: February 2005

AbstractThe spatial distribution of collagen loss in syngeneic grafts of skin was studied autoradiographically. Grafts of radioactive skin from rats that were chronically injected with 14C‐ or 3H‐proline were placed onto unlabeled inbred rats. These radioactive skin grafts were removed at 0, 2, 4, 8 and 20 weeks after grafting, and observed both for distribution of isotope, as determined by autoradiography, and histological changes. Since 91% of the total radioactivity in the skin resided in collagen, the autoradiographs were specific for collagen.Thick full‐thickness and split‐thickness grafts showed a zonal loss of radioactivity, with isotope being lost most rapidly in the subepidermal region. Collagen newly formed in this area resembled scar collagen.Thin full‐thickness grafts did not show a zonal reduction of isotope, but instead lost radioactivity in a diffuse manner. The newly synthesized collagen bundles of the thin full‐thickness grafts were similar in thickness to the collagen bundles of control skin, but did not form the lattice network seen in the controls.Autoradiographic losses and histological changes are related to the biochemical quantification of collagen turnover, to scar formation, and to the cellular control of collagen mass in skin grafts.
The origin of equine endometrial cups. III. Light and electron microscopic study of fully developed equine endometrial cups
Authors: Hamilton D. W. , Allen W. R. , Moor R. M. 
Published: February 2005

AbstractEquine endometrial cups are localized endometrial outgrowths which develop in mares during early pregnancy and secrete pregnant mares serum gonadotrophin (PMSG).The principal cell‐type found in endometrial cups is large, regular and epithelioid in appearance. These cup cells have one or two large euchromatic nuclei with dense, characteristic nucleoli. Their cytoplasm is filled with irregular profiles of endoplasmic reticulum containing pale flocculent material. Lipid droplets and a few mitochondria are also present. Golgi material is not prominent and the absence of membrane‐bound secretory granules suggest that the Golgi apparatus does not package a secretory product. The plasmalemma is mostly smooth in outline but is modified in some places to form short microvilli or complex intercrescent folds.
Morphogenesis of the ovarian interstitial tissue in the neonatal mouse
Authors: Quattropani Steven L. 
Published: February 2005

AbstractThe development of the mouse ovarian interstitial tissue was examined by light and electron microscopy at postnatal days 9, 10, 11, 12, and 18. Prior to day 12 the ovarian stroma is composed of fibroblast‐like cells. These cells contain rough endoplasmic reticulum, elongate mitochondria with lamellar cristae, and lipid bodies which appear uniformly electron opaque. On postnatal day 12 islands of lipid containing cells are seen deep in the interfollicular stroma. These cells referred to as interstitial cells have rounded mitochondria with tubular cristae, smooth endoplasmic reticulum, lipid bodies with extracted centers, well‐developed Golgi complexes, and solitary cilia lacking the central tubular elements. By postnatal day 18 similar cells are seen in the thecal regions of normal appearing follicles. Also seen in the theca are cells whose cytoplasm contains characteristics of both fibroblasts and interstitial cell.It is proposed that the interstitial cells develop from the fibroblast‐like stromal cells, that this development proceeds in a wave from deep in the interfollicular tissue toward the follicle, and that the interstitial cells are the source of ovarian steroid production during this period of development.