bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of the L‐proline analog, L‐azetidine‐2‐carboxylic acid (LACA) to analyse embryonic growth and determination and expression of the chondrogenic phenotype in vivo and in vitro
Authors: Hall Brian K. 
Published: February 2005

AbstractThe L‐proline analog, L‐azetidine‐2‐carboxylic acid, (LACA) was injected into embryonated eggs of the common fowl, Gallus domesticus at daily doses of 350 μg/egg on one or several days between 8 and 12 days of incubation. Treatment at nine‐days of incubation preferentially retarded embryonic growth to the twelfth day but recovery of growth rate occurred by 15 days of incubation. Relationships between growth and LACA‐inhibited aspects of collagenogenesis are discussed.The earliest aged embryos from which isolated stem cells from membrane bones will form secondary cartilage is ten days of incubation. Secondary chondro‐genesis on the quadratojugal, a membrane bone of the skull, was inhibited by treatment of whole embryos with LACA at nine days of incubation but not by treatment at eight days. We concluded that an event involving collagen began at nine days of incubation, was blocked by LACA, and was part of the process of chondrogenic determination of these stem cells. Addition of LACA to the medium in which already determined stem cells from the quadratojugal were cultured prevented expression of the chondrogenic phenotype. This proline analog is then a useful probe for events relating both to determination and to expression of the differentiated state, and allows conclusions to be drawn regarding the role of col‐lagenogenesis in these events.
The ultrastructure of normal myogenesis in the limb of the mouse
Authors: Platzer Ann C. 
Published: February 2005

AbstractThe ultrastructure of myogenesis in the mouse hind limb has been studied from day 12 to birth. Mononucleated cells with myofilaments are small and infrequent during myogenesis and never line myotubes. Only mononucleated cells without myofilaments cover the myotubes and are involved in mass fusion. These mononucleated cells are pleomorphic and undifferentiated during early myogenesis. They have a heterochromatic nucleus and many accumulate mitochondria and lengthen during days 16‐18. After day 18 they are normally elongate with a heterochromatic nucleus and packed with free ribosomes. The multinucleated cell development may be divided into four stages. 1. Immature myotube (days 14‐15). Their fibrils are small, out of register and some poorly defined. Many myofilaments are not in rigid hexagonal alignment. The sarcoplasmic reticlum is simple and randomly oriented and triads are absent. Large clumps of glycogen occur between euchromatic nuclei which are in chain formation. 2. Mature myotube (days 16‐18). Small groups of fibrils show alignment. Glycogen granules and sarcoplasmic reticulum become numerous between fibrils. Triads are sparse and mitochondria cluster in subsarcolemmal regions and between nuclei. 3. Young myofibers are present by day 19. More fibrils are aligned and compact. The filaments are in a rigid hexagonal array, the glycogen is dispersed and nuclei are peripherally located and moderately heterochromatic. Triads are frequent but often obliquely oriented and mitochondria are elongate and numerous between fibrils. 4. Mature myofibers occur postnatally (2 weeks).
Development of the fetal pituitary‐testicular system based on observation of leydig cells in encephalectomized, hypophysectomized and control fetal rats
Authors: Eguchi Yasunobu , Arishima Kazuyoshi , Nasu Tetsuo , Toda Mineyuki , Morikawa Yoshio , Hashimoto Yoshiyuki 
Published: February 2005

AbstractThe time of onset of brain regulation of the pituitary‐Leydig cell system in fetal rats was assessed by fetal encephalectomy, which allowed the pituitary to persist in situ. The effects of encephalectomy were compared with those of fetal hypophysectomy (surgical decapitation). The parameter for in terpretation of these effects was the collective volume of Leydig cells, measured by the method of Chalkley ('43). The normal increase in the collective volume of Leydig cells in fetuses encephalectomized on day 17 of gestation and autopsied on day 18 was not retarded, whereas that in decapitated fetuses of the same age was retarded. In all other one‐day experimental periods (day 18–19, 19–20, 20–21, and 21–22), the increase in volume was retarded to approximately the same extent in encephalectomized as in decapitated fetuses. The collective volume of Leydig cells continued to increase to some extent without the brain until day 20, after which it ceased to increase. The results suggest that in fetal rats, the brain control of the pituitary‐Leydig cell system begins to operate from day 18 of gestation, when the day following overnight mating was designated as day 1 of gestation.
Rapid isolation of chloride cells from pinfish gill
Authors: Hootman Seth R. , Philpott Charles W. 
Published: February 2005

AbstractEnriched fractions of chloride cells with good ultrastructural integrity have been obtained from gill filaments of the euryhaline teleost, Lagodon rhomboides. The branchial epithelium from seawater‐adapted fish was dissociated by gentle mechanical means in a Ca++, Mg++ ‐free balanced salt solution. Density gradient centrifugation of the mixed cell suspensions through a Ficoll gradient yielded a fraction containing between 50 and 70% chloride cells. This fraction showed a 3‐ to 4‐fold enrichment over comparable gill homogenate values for sodium plus potassium‐activated adenosinetriphosphatase, (Na+, K+‐ATPase), an enzyme concentrated in chloride cells. Isolation of chloride cells from fish adapted to one‐third seawater was less successful, due to the smaller size and reduced number of these cells, although fractions with at least a 2‐fold enrichment of the enzyme were obtained. These results continue to support the belief that chloride cells are responsible for the osmoregulatory activity associated with the branchial epithelium of teleosts and that this vital function is mediated through the activity of the transport associated enzyme, Na+, K+ ‐ATPase, the specific activity of which increases with osmotic stress.
Heterogeneity of the MtTW15 mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay
Authors: Parsons Jonathan A. , Erlandsen Stanley L. , Carpenter Anna‐Mary , Debault L. E. 
Published: February 2005

AbstractLarge MtTW15 pituitary tumors produced 200‐ to 800‐fold elevations in serum growth hormone (GH) and prolactin (PRL) levels. Female tumor hosts showed doubling in body weight, milk secretion, and a 2‐fold hepatosplenomegaly. Pituitaries of host animals were reduced by about 50% in both weight and concentrations of GH and PRL. Large tumors were well‐encapsulated, multinodular and showed variable amounts of necrosis and hemorrhage. Cytofluorometric analysis revealed a range of 100‐fold in nuclear DNA content of tumor parenchymal cells which were chromophobic, pleomorphic and frequently mitotic. Concentrations of hormones in tumors were less than in normal pituitaries and highly variable with the ratio of GH/PRL ranging up to 30‐fold within the same tumor. Immunostaining and linear scanning quantitation showed that about 50% of the tumor cells contained immunodetectable hormones. Comparison of immunostained adjacent sections showed that hormone‐containing tumor cells were pleomorphic, unequally distributed within nodules, lacking in distinctive identifying morphological characteristics and that they contained GH or PRL but not both hormones simultaneously. Collectively our results show that large MtTW15 tumors are comprised of a markedly heterogeneous population of tumor cells and they suggest that the hormone‐containing cells are monohormonal secreting tumor cells which can produce GH or PRL but not both hormones.
Gross and histological variations along the length of the rat vas deferens
Authors: Hamilton D. W. , Cooper T. G. 
Published: February 2005

AbstractThe gross morphology of the vas deferens of the rat and the changes that occur along its length are reported. It is shown that the organ can be divided into proximal, distal and terminal portions. Each portion is histologically unique and is situated in a different part of the body. The differences are discussed in relation to the function of the organ and their possible role in the consequences of vasectomy.
Actin‐ and myosin‐like filaments in rat brain pericytes
Authors: Lebeux Yvi J. , Willemot Joan 
Published: February 2005

AbstractHeavy meromyosin (HMM) labeling was used to identify the nature of the filaments which form bundles in the cytoplasm of the pericytes in brain tissue. Rat brain tissue pieces were incubated in glycerol solutions at 4°, and then transferred into buffer (pH 7.0), (1) without HMM, (2) with HMM, (3) with HMM + 5 mM ATP, and (4) with HMM + 2.5 mM Na+ pyrophosphate. In pericytes from untreated tissue, smooth‐surfaced microfilaments, averaging 6 nm in diameter, appear to branch and anastomose and to anchor on the plasma membrane. After exposure to HMM, the number and the density of the microfilaments are strikingly increased. These tightly‐packed microfilaments are now heavily coated with exogenous HMM thus increasing in width to 18–20 mm. They intertwine in closely‐woven networks. After incubation in HMM solutions containing ATP or Na+ prophosphate, they are no longer coated with thick sidearms. It can thus be concluded that these microfilaments are of actin‐like nature. In addition, after incubation in ATP, they are intermingled with, and converge onto the surfaces of, thick, tapered filaments, which we have tentatively identified as of myosin‐like nature. Thus, it appears that certain of the major elements necessary for contraction are present in brain pericytes.
Ultrastructural identification of collagen and glycosaminoglycans in notochordal extracellular matrix in vivo and in vitro
Authors: Kenney M. Cristina , Carlson Edward 
Published: February 2005

AbstractNotochordal extracellular matrix consists of a continuous basal lamina, amorphous materials and microfibrils embedded in a ground substance of low electron density. Together they comprise the notochord sheath and are of considerable interest because of their suspected role in early embryonic tissue interactions. The notochord is particularly well‐suited to morphological investigation of extracellular matrix because it is one of the few embryonic epithelia which produces ultrastructurally recognizable stroma in vitro without the advantage of a collagenous substratum. Furthermore, these matrix components produced in vitro are morphologically identical to those observed in vivo. The present study uses ruthenium red staining to demonstrate that notochordal microfibrils exhibit collagen‐like cross‐banding patterns both in vivo and in vitro. Collagenase and testicular hyaluronidase digestion studies designed to localize collagen and glycosaminoglycans show a reduction of microfibrillar diameters by 30‐35%. Furthermore, these enzyme treatments frequently result in enhanced striations of microfibrils. When cis‐hydroxyproline (a proline analog) or beta‐aminoproprionitrile (BAPN, a lathyrogenic compound) is added to the culture medium, a similar reduction in microfibrillar diameters is seen. Moreover, increased ruthenium red‐positive surface coats and large collagen fibrils are frequently present in BAPN‐treated cultures, implying a stimulatory metabolic effect.We conclude that most, if not all, notochordal extracellular matrix components are composed of both collagen and glycosaminoglycans and suggest that the entire extracellular matrix should be considered a macromolecular composite which acts in concert to induce or stabilize developmental interactions.
Cilia of neonatal articular chondrocytes incidence and morphology
Authors: Wilsman Norman J. , Fletcher Thomas F. 
Published: February 2005

AbstractCilia in neonatal canine articular chondrocytes were studied using morphometric techniques and transmission electron microscopy. The cilia in chondrocytes were morphologically similar to cilia in a variety of other cell types. A chondrocytic cilium consisted of a basal body and a ciliary shaft. The cylindrical basal body was 0.21 μm (S.D. = 0.01 μm) in diameter, 0.50 μm (S.D. = 0.03 μm) in length and contained nine microtubular triplets. The ciliary shaft was 0.196 μm (S.D. = 0.02 μm) in diameter and 1.76 μm (S.D. = 0.80 μm) in length. The number of microtubular doublets in the ciliary shaft varied depending on where along the length of the shaft the section was taken.This study demonstrates that on the average the frequency of cilia in neonatal articular chondrocytes, as estimated stereologically, was about one cilium per cell.
Perisynaptic satellite cells in the developing and mature rat soleus muscle
Authors: Kelly Alan M. 
Published: February 2005

AbstractIn mature rat soleus muscle it is shown that satellite cells are not evenly distributed over the surface of myofibers but are more numerous in the vicinity of the motor endplate. In this location they commonly lie close to the post synaptic membrane where they are termed perisynaptic satellite cells. In developing muscle several satellite cells may be seen close to the endplate and give the impression of limiting the spread of the axon over the myofiber. In addition these satellite cells make close plasmalemmal contact with Schwann cells and appear as a continuation of the Schwann sheath onto the surface of the myofiber.
Secretagogue‐mediated discharge of nerve growth factor from granular tubules of male mouse submandibular glands: An immunocytochemical study
Authors: Simson J. A. V. , Hazen D. , Spicer S. S. , Murphy R. A. , Young M. 
Published: February 2005

AbstractSubmandibular glands of male mice were stained for nerve growth factor by light microscopic immunocytochemistry. Nerve growth factor (NGF) was present in the granules of granular tubule cells, with the immunoreactive material often concentrated at the periphery of granules. Administration of the α‐adrenergic agent, phenylephrine, to animals resulted in a marked depletion of NGF‐containing granules from granular tubules. Some release also occurred following administration of the β‐adrenergic agent, isoproterenol. Cholinergic stimulation (pilocarpine) did not result in appreciable loss of immunoreactive granules from these cells. In vitro results were not as clear cut, immunocytochemically, as those obtained with intact animals. It is concluded that discharge of NGF from male mouse submandibular glands is mediated predominantly by α‐adrenergic activation, and that this phenomenon is readily demonstrated in the intact animal.
Surface morphology of bone marrow lymphocytes. I. Scanning electron microscopy of small lymphocytes bone marrow and spleen
Authors: Kammerer W. A. , Osmond D. G. 
Published: February 2005

AbstractCell separation techniques and scanning electron microscopy (SEM) were used to characterize the surface morphology of small lymphocytes in mouse bone marrow. Lymphocyte‐rich fractions and unfractionated suspensions of bone marrow and spleen cells from 9‐10‐week‐old C3H male mice were glutaraldehyde‐fixed, syringed onto gelatin‐coated silver membranes, dehydrated in ethanol, infiltrated with amyl acetate, critical point dried, coated with gold‐palladium and examined by SEM. High proportions of cells were retained on the membranes. Purified spleen small lymphocytes showed unimodal distribution curves for cell diameter (mode, 3.4 μm) and for number of surface microvilli (mode, 55‐60). Bone marrow small lymphocytes were identified initially in lymphocyte‐rich marrow fractions and in erythroblast‐depleted marrow from polycythemic mice as well as in normal whole marrow. The cells resembled spleen small lymphocytes in size distribution and they showed microvilli. However, the number of visible microvilli was lower on small lymphocytes in the bone marrow (mode, 35‐40) than in the spleen. While in each small lymphocyte population the total number of microvilli was greater on larger cells than on smaller ones, the density of microvilli per unit area of cell surface tended to decrease with increasing cell size. The results establish that the small lymphocytes in mouse bone marrow, mainly locally‐produced immature cells, have villous surfaces, but the number of microvilli per unit cell surface area is less than that on peripheral small lymphocytes, as seen in the spleen. Neither in the bone marrow nor in the spleen are subpopulations of small lymphocytes distinguishable solely by numbers of microvilli. The findings suggest that microvilli on bone marrow small lymphocytes may undergo further development during post‐mitotic maturation, surface receptor expression and migration of the cells to peripheral lymphoid tissues.
Distribution of surface coat material on nasal folds of mouse embryos as demonstrated by concanavalin A binding
Authors: Burk Dorothy , Sadler T. W. , Langman Jan 
Published: February 2005

Abstract3H‐concanavalin A and the concanavalin A‐horseradish peroxidase staining technique were used to study the distribution of surface coat material on the epithelium of the nasal folds and nasal groove of mouse embryos. In stages shortly before and during epithelial fusion concanavalan A stained or labeled material was present at apical surfaces of epithelial cells of the nasal groove and nasal folds. Silver grains, representing bound 3H‐concanavalin A, were counted in defined areas of the nasal groove and presumptive fusion area in both anterior and posterior regions of the nasal folds. For both stages examined there was a significant increase in the amount of 3H‐concanavalin A bound by presumptive fusion areas in posterior regions of the nasal folds as compared with anterior regions; i.e., the amount of surface coat was greater in the region just prior to the point of contact between the nasal folds. This finding is consistent with results from investigations of palatal shelf and neural fold fusion which suggest that increased synthesis of surface coat material is associated with adhesion and fusion of epithelial folds and shelves.
A qualitative and quantitative study of rete ovarii development in the fetal rat: Correlation with the onset of meiosis and follicle cell appearance
Authors: Stein Larry E. , Anderson Conwell H. 
Published: February 2005

AbstractDevelopment of the rete ovarii and its contribution to the cells of the ovary were examined in fetal rats. Histochemical and autoradiographic techniques were used for the observations between days 15 and 21 of gestation. The data presented indicate that the rete system contributes somatic cells to the ovary before birth.The basement membrane which surrounds the cuboidal epithelium of the mesonephric tubules immediately adjacent to the ovary becomes discontinuous on day 15 of gestation. The mesonephric epithelial cells in this region form a knot or clump of pleiomorphic cells, with no apparent tubular organization, and this clump later becomes surrounded by a basement membrane. On day 17 of gestation the newly established fetal rete ovarii is comprised of three regions; (1) the extraovarian mesonephric tubules (ER), (2) intraovarian cords of flattened epithelioid cells which surround the oogonia (IR), and (3) a knot or clump of cells connecting the ER and IR regions (CR). The entire rete system is enclosed by a continuous basement membrane as defined by Periodic Acid‐Schiff Reagent techniques.Autoradiographic and quantitative analyses demonstrate that the ER tubule cells proliferate and are incorporated into the other regions of the rete system. These processes begin on day 17 and continue until at least day 21 of gestation. The role these mesonephric tubule cells may play in the regulation of meiosis and their early contribution to the presumptive granulosa cell population is discussed.
Fine structure of the adrenocortical homologue in the north American eel and modifications following seawater adaptation
Authors: Bhattacharyya Tapan Kumar , Butler David Gordon 
Published: February 2005

AbstractThe ultrastructure of the adrenocortical homologue (AH) of the north American eel (Anguilla rostrata) was studied from freshwater and long‐term (1.5 years) seawater (SW) adpated animals. The AH tissue situated in the wall of cardinal veins is surrounded by a thin layer of collagenous capsule; in the region away from the vein wall, parenchymal cells are separated by interstitial lacunae containing collagen bundles, capillaries, chromaffin cells and nerve fibers often applied closely to the surface of AH cells. The free surface of the cell near the vein wall, capillaries or interstitial space extends numerous slender microplicae. The cytoplasm is characterized by the presence of mitochondria with tubular cristae, a network of smooth endoplasmic reticulum, a few cisternae of rough surfaced endoplasmic reticulum, well developed Golgi apparatus, coated vesicles, centrioles, cilium, filaments, microtubules, dense bodies of variable nature and a scarcity of liposomes. The cell nuclei possess invaginated cytoplasmic pseudo‐inclusions. Electron histochemical reaction for free cholesterol revealed the occurrence of needle‐shaped crystals mainly associated with surface microplicae and smooth endoplasmic reticulum, which seems to be the major organelle for storage or synthesis of this steroid precursor. SW animals indicated ultrastructural signs of stimulated steroid synthesis and secretion, i.e., high degree of pseudo‐follicle formation, increased electron density of mitochondria, greater abundance of lysosomal dense bodies, hyperactivity of Golgi apparatus and dilation of smooth endoplasmic reticulum tubules. Some SW fishes showed extensive deposition of osmiophilic inclusions in the mitochondria and stacks of elongated cup‐shaped mitochondria. Chronic seawater acclimation enhances AH activity as judged by ultrastructural criteria with ultimate mitochondrial degeneration resulting possibly from prolonged cortisol hypersecretion; the latter may be linked with physiologic re‐adjustment of ionic transfer mechanism in hyperosmotic medium.
Ultrastructure of the apocrine‐sebaceous anal scent gland of the woodchuck, Marmota monax: Evidence for apocrine and merocrine secretion by a single cell type
Authors: Smith Janet D. , Hearn Gail W. 
Published: February 2005

AbstractLight and electron microscope studies of the woodchuck anal scent gland revealed that it is composed of apocrine and sebaceous components emptying into a common duct. In the apocrine acini, the single secretory cell type showed evidence of both merocrine and apocrine secretion. Merocrine secretion resulted in the release of the contents of apical secretory granules while apocrine secretion released apical caps of cytoplasm by a process involving the following: (1) formation of an apical cap, usually containing no organelles or secretory granules; (2) appearance of a single row of flattened vesicles forming an incomplete barrier between the apical cap and the remaining cell cytoplasm; and (3) fusion between vesicles and plasmalemma, causing progressive constriction of the neck of the apical cap and eventual cap release. Since both merocrine and apocrine secretory processes have been reported in three other types of apocrine glands, it is likely that the occurrence of both processes in a single cell is a general characteristic of apocrine cells.Several features apparently unique to these particular apocrine cells were observed, including secretory granules of a single morphological type and a population of small dense‐cored basal vesicles of unknown function. Therefore, it would appear that, just as with merocrine cells, apocrine cells from different types of glands also have distinctive morphologies which probably reflect real differences in their functions and products.