bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shaping, invagination, and closure of the chick embryo otic vesicle: Scanning electron microscopic and quantitative study
Authors: Alvarez Ignacio S. , Navascués Julio 
Published: February 2005

AbstractScanning electron microscopy, light microscopy, and morphometric analysis were used to study the morphological changes of the otic placode and vesicle before and during invagination and closure processes. Our results reveal that the otic placode undergoes shaping between stages HH9 and HH12; during this period the rostrocaudal axis is shortened, while the lateromedial axis of the placode lengthens. The presence of long cytokinesis bridges during this period suggests that cellular displacements after mitosis may participate in the shaping of the otic placode. The shaping process appears to facilitate the approach of the otic placode to the neural tube. From stage HH12 on, the otic anlage gradually becomes a U‐shaped structure with its medial portion in intimate apposition to the rhombencephalic neural tube. The coincidence in time between the beginning of intimate otic anlage–rhombencephalon contact and active invagination suggests that these two processes are related.Changes occurring at the edges of the otic vesicle until their disappearance in stage HH17 suggest that, in addition to a process of invagination, the edges of the otic anlage become bent. During closure, cells at the edges of the otic vesicle differ in apical morphology according to their topographical location: The cells between the rostral and lateral edges have elongated apices, in contrast with the polygonal shape of the cell apices in other places of the edges. In the opposite side (between the caudal and medial edges) cell death is observed. Closure of the otic vesicle conceptualized as a zipper‐like model is discussed.We propose that early development of the otic anlage takes place in four stages: (1) shaping (stages HH9–11); (2) triggering of the invagination (stage HH12); (3) early invagination and lateral bending (stages HH13–15); and (4) late invagination and closure (stages HH16–17).
Atrial‐specific granule number and plasma atrial natriuretic peptide in rats: Effects of beta‐adrenoceptor blockade and sodium intake
Authors: Penner S. Brian , Thliveris James A. , McKenzie John K. , Smyth Donald D. 
Published: February 2005

AbstractAn interrelationship between atrial natriuretic peptide (ANP) and the renin‐angiotensin system has been established. Both of these hormonal systems are modulated by sodium balance. The role of the beta‐adrenoceptor in the regulation of release of ANP is not clear. We therefore undertook a study to examine changes in atrial‐specific granule number and plasma ANP level following beta‐adrenoceptor blockade in rats on low and high sodium intakes. A low‐sodium diet, as compared with a high‐sodium diet, elevated right and left atrial‐specific granule number (right atria 54.6 ± 8.7 vs. 42.3 ± 5.7; left atria 47.7 ± 7.7 vs. 30.6 ± 3.4 granules/unit area) and plasma renin activity (28 ± 3.7 vs. 5.4 ± 0.8 ng Al/ml/hr). Plasma ANP levels were lower in the low‐sodium animals (98 ± 34 vs. 345 ± 38 pg/ml). When treated with the nonspecific beta‐adrenoceptor blocker propranolol, the elevated plasma renin activity and atrial‐specific granule number in rats on a low sodium intake were significantly less. Neither of these parameters changed in rats on a high sodium intake. Conversely, propranolol treatment resulted in lower plasma ANP levels in rats with high sodium intake. The already‐suppressed plasma ANP level in rats on a low‐sodium diet was unaltered with beta‐adrenoceptor blockade. The results suggest that dietary sodium intake is an important determinant of the response of atrial‐specific granule number and plasma ANP levels following beta‐adrenoceptor blockade with propranolol.
Inducible perivascular cells contribute to the neochondrogenesis in grafted perichondrium
Authors: Diaz‐Flores Lucio , Gutierrez Ricardo , Gonzalez Pilar , Varela Hilda 
Published: February 2005

AbstractAutogeneic perichondrium was implanted above the cremaster muscle of the rat, and the new formation of two types of cartilage (types I and II) was confirmed. Also, granulation tissue was observed before the type II cartilage formation. Under these conditions, the contribution to the neocartilage of graft bed derived cells, mainly of the venule pericytes, was studied. To follow the pericyte lineage, we used a marker—Monastral Blue B—the administration of which was based on the principle of vascular labeling. While the perichondrium was kept free, before its implantation, the preformed (preexisting) venules in the cremaster muscle were exclusively labeled with Monastral Blue B, which was incorporated into the cytoplasm of pericytes and endothelial cells. After perichondrium implantation, the following sequence in tracer distribution was demonstrated. During the earlier stages, labeling was restricted to the pericytes and endothelial cells of venules in the graft bed. Later the tracer was observed in some endothelial cells and pericytes of the growing vessels and in fibroblast‐like cells of the granulation tissue. Finally, some type II neochondrocytes appeared labeled. Tracer was not found in type I neochondrocytes. The presence of label in type II neochondrocytes demonstrates that they arise from progenitor cells present in the graft bed, principally from small venule pericytes. Therefore, the findings in this study provide greater evidence that surrounding soft tissues may increase the process of cartilage regeneration from cells present in the perichondrium by contributing inducible perivascular cells.
The Golgi apparatus of rat pachytene spermatocytes during spermatogenesis
Authors: Suarez‐Quian Carlos A. , An Qu , Jelesoff Nicole , Dym Martin 
Published: February 2005

AbstractA morphological and immunocytochemical study of the Golgi apparatus in pachytene spermatocytes was performed in an effort to correlate the structure and function of this organelle during meiotic prophase. In stages I‐III of the cycle, the Golgi complex of pachytene spermatocytes is a flattened discoid, 0.5–1 μm in diameter, composed of vesicles interspersed with classically described Golgi cisternae. During subsequent maturation of pachytene spermatocytes (stages IV–XIII), the size of the Golgi complex increases significantly, attaining a size of 2–3 μm. However, unlike pachytene spermatocytes of stages I–III, the majority of the Golgi complex of more mature spermatocytes is characterized by an abundance of distinct stacks of cisternae interspersed with numerous vesicles and tubules. The composition of the Golgi complex was also studied by using two monoclonal antibodies that recognize either the cis or the trans Golgi cisternae, respectively, and employing biotin‐streptavidin‐peroxidase immunocytochemistry in 5 μm frozen sections of testes. Immunodetection of the distinct cisternae revealed that the increase in size of the Golgi complex during maturation of pachytene spermatocytes was due predominantly to an accumulation of trans Golgi; the amount of cis Golgi remained unchanged.The morphological data presented in this study are consistent with an heightened secretory activity of pachytene spermatocytes during their maturation. In addition, the increase in size of the Golgi apparatus during the extensive prophase of pachytene spermatocytes may suggest that the mechanism employed by germ cells to partition the Golgi complex during the first division of meiosis varies significantly from that of somatic cells undergoing mitosis.
An ultrastructural, morphometric analysis of rabbit fetal lung type II cell differentiation in vivo
Authors: Snyder Jeanne M. , Magliato Susan A. 
Published: February 2005

AbstractRabbit lung type II cell differentiation was evaluated by use of ultrastructural, morphometric techniques. Fetal lung epithelial cells decreased in size dramatically from day 19 to day 21 of gestation. Thereafter, the cell and cytoplasmic cross‐sectional area declined gradually until the neonatal time point. The tall columnar cell shape characteristic of fetal lung epithelial cells at early stages of development became cuboidal by day 24 of gestation. The number of mitochondria per μm2 cytoplasmic area in presumptive alveolar epithelial cells and the mitochondrial volume density increased toward the end of gestation. The volume density of glycogen pools within fetal lung epithelial cells reached a plateau on day 21 of gestation and then declined sharply on day 26 of gestation in lamellar body‐containing, type II epithelial cells. Lamellar bodies increased in number and volume density in epithelial cells starting on day 26 of gestation and peaked with respect to these parameters in the neonatal lung tissue. Multivesicular bodies, which are thought to be a precursor to the lamellar body, became more prominent in differentiated type II cells on day 26 of gestation and increased in volume density from day 28 of gestation to the adult time point. The distance between mesenchymal and epithelial cells in fetal lung tissue declined sharply between days 24 and 26 of gestation but remained relatively constant thereafter. Foot processes extending from connective tissue cells contiguous to the epithelium were generally more numerous than those extending from the basal plasma membrane of epithelial cells at every stage of development examined. These data quantitate for the first time key ultrastructural events that occur during the differentiation of fetal lung epithelial cells in vivo.
Initial stages of sperm‐egg fusion in the freshwater teleost, Rhodeus ocellatus ocellatus
Authors: Ohta Tadayuki 
Published: February 2005

AbstractThe morphology of spermatozoa and the initial stages of spermegg fusion at fertilization were investigated ultrastructurally in the rose bitterling, Rhodeus ocellatus ocellatus. Each spermatozoon is composed of a spherical head without an acrosome, two centrioles, a large mitochondrion, and a flagellum. Freeze‐fracture of spermatozoa illustrates that specialized arrays of intramembranous particles (IMPs) are present on the protoplasmic facing (PF) surface of the head plasma membrane at the portion slightly in front of the centrioles. The specialized arrays, whose functions are uncertain, are parallelogram‐like in shape. The distribution of the particles is random and less compact in other areas of the head plasma membrane. The number of particles on the PF surface is larger than that on the extracellular facing (EF) surface. The complementary structures of the specialized arrays are also found on a similar portion of the EF surface. An ultrastructural study clearly shows fusion of gamete plasma membranes at the initial stages of sperm entry into the egg. Membrane fusion is first observed in eggs fixed 10 seconds after insemination in fresh water. The fusion site is the microvillus membrane of a sperm entry site on the egg and the head membrane of the spermatozoon. The plasma membrane fusion of gametes is discussed relative to the distribution of the IMPs and the fusion site.
Organization of the reticular network of rabbit Peyer's patches
Authors: Ohtani Osamu , Kikuta Akio , Ohtsuka Aiji , Murakami Takuro 
Published: February 2005

AbstractThe organization of the network of collagen fibers of rabbit Peyer's patches was examined by scanning electron microscopy (SEM) in alkali‐water macerated tissues. The relationship between this network and the reticular cells within it was further studied by SEM of ultrasonicated tissues. Collagen fibrils (about 60 nm in diameter) formed collagen fibers or sheets. There were sheets of collagen fibrils with numerous pores beneath the patch dome epithelium. Within the patches, collagen fibers repeatedly divided and fused, forming the reticular network. The reticular network within the follicle was looser than within the dome, the corona, or the interfollicular area. The latter three compartments showed similar structures and consisted of numerous intercommunicating small subcompartments. Reticular cells were in contact with groups of free cells lodged in these subcompartments within the reticular network. Reticular cell processes with numerous fenestrations embraced not only collage fibers forming the reticular network, but also sheaths of collagen fibers of blood and lymphatic vessels. Sheaths of collagen fibers of high endothelial venules and lymphatic vessels were also fenestrated, indicating the sites through which lymphocytes and other free cells migrate. These results indicate that the reticular network of Peyer's patches is organized so as to facilitate migration and lodging of free cells and thus facilitate antigen‐to‐cell and cell‐to‐cell interactions during an immune response. The naked areas on the collagen fibers seem to provide a scaffolding for free cells during their migration.
Straining puborectalis reflex: Description and significance of a “new” reflex
Authors: Shafik Ahmed 
Published: February 2005

AbstractThe present communication studies the technique and clinical significance of a new reflex, termed straining puborectalis reflex. Nineteen healthy volunteers with an average age of 38.2 years were studied, including ten males and nine females.The intravesical pressure, representative of intra‐abdominal pressure, was measured by means of a balloon‐tipped catheter introduced into the urinary bladder and connected to a pressure transducer. The electromyographic (EMG) activity of the puborectalis muscle was recorded using a concentric needle electrode inserted into the muscle. The EMG response of the puborectalis muscle to straining at different pressures was recorded. The response to two types of straining–sudden momentary and slow, sustained–was observed. The procedure was repeated in ten subjects after puborectalis infiltration with xylocaine or saline.Sudden straining evoked puborectalis contraction, whereas slow, sustained straining did not. Puborectalis contraction increased with the increase in straining intensity. These results were reproducible. The anesthetized puborectalis did not respond to straining, whereas the saline‐infiltrated muscle did. The latency of the reflex was studied.Besides its role as a voluntary continent sphincter, the puborectalis seems to have a role also in the involuntary continence of the pelvic organs through the straining‐puborectalis reflex. The muscle contracts on sudden straining, sealing the rectal and vesical necks and thereby preventing fecal or urinary leak. However, it is only on sudden straining that the puborectalis contracts. Slow, sustained straining as occurs during defecation and micturition does not evoke the reflex action. The straining puborectalis reflex is informative and may be incorporated as an investigative tool in patients with fecal and urinary control disorders.
Immunocytochemical localization of an oviductal zona pellucida glycoprotein in the oviductal epithelium of the golden hamster
Authors: Abe Hiroyuki , Oikawa Taneaki 
Published: February 2005

AbstractThe immunocytochemical localization of an oviductal glycoprotein associated with ovulated eggs was investigated. Using a monoclonal antibody, we studied three regions of epithelium in the golden hamster oviduct. The monoclonal antibody reacted with the oviductal epithelium throughout the fimbriae and isthmus. Intense binding was observed in the ampulla and isthmus, especially in the caudal isthmus. In addition, reactive materials were present in the ovarian bursal sac and lumen of the ampulla. At the ultrastructural level, the monoclonal antibody reacted specifically with putative secretory granules and Golgi apparatus of nonciliated cells in the oviductal epithelium. Other cellular organelles did not react. Quantitative data indicated that the immunolabelings were intense in the ampullar and isthmic cells but weak in the fimbrial cells. Lipid droplet‐like granules of the fimbriae and lysosome‐like vesicles of the isthmus did not react with the monoclonal antibody. In all cases, ciliated cells did not react with the monoclonal antibody. These results suggest that the glycoprotein is primarily produced and secreted by ampullar and isthmic secretory cells and is then accumulated in the ovarian bursal sac. These findings may provide insight into regional and cellular differences in secretion of the golden hamster oviduct.
Immunocytochemical localization of cathepsin D in rat ventral prostate: Evidence for castration‐induced expression of cathepsin D in basal cells
Authors: Wilson Michael J. , Whitaker John N. , Sinha Akhouri A. 
Published: February 2005

AbstractCathepsin D (EC3.4.23.5) is an aspartyl endopeptidase involved in lysosomal proteolysis. Its functional role is uncertain. This study was undertaken to determine the cellular and subcellular distribution of cathepsin D in the normal rat ventral prostate and its possible role in the castration‐induced atrophy of the gland. Cathepsin D was localized immunohistochemically to perinuclear lysosomes in secretory cells, in capillary endothelial cells, and, occasionally, in stromal cells of the untreated animal. Castration resulted in an increased number of cathepsin D‐positive cells in the stroma within 24 hr. By 48 hr after castration autophagolysosomes formed in secretory cells and apoptotic bodies appeared in the epithelium. Although apoptotic bodies generally contained immunoreactive cathepsin D, a subpopulation of larger apoptotic bodies, which commonly rested on the basement membrane and contained multiple inclusions, were more variable in cathepsin D expression. The induction of cathepsin D in dendritic cells basally oriented in the epithelium was noted at 4 days of castration. These cells had a phagocytic phenotype, were distributed periodically along the basement membrane, and were not found in ductal epithelia. Treatment with actinomycin D or hydrocortisone to reduce the rate of regression of the ventral prostate blocked the appearance of these cathepsin D‐positive, basally oriented epithelial cells. Our data indicate that this cathepsin D‐positive, phagocytic cell differentiates from a cell resident in the prostatic epithelium. We suggest that it differentiates from basal cells in the secretory tubuloalveolar portion of the gland and that it is involved in the destruction of regressed secretory cells.
The proximal border of the human respiratory unit, as shown by scanning and transmission electron microscopy and light microscopical cytochemistry
Authors: Have‐Opbroek Ank A. W. Ten , Otto‐Verberne Caroline J. M. , Dubbeldam Jacqueline A. , Dÿkman Joop H. 
Published: February 2005

AbstractThe epithelial cell types present in respiratory (= distal alveolarized) and terminal (= distal nonalveolarized) bronchioles in adult human lung were characterized with scanning and transmission electron microscopy (SEM, TEM) and light microscopic cytochemistry, using specific antibodies against surfactant protein SP‐A and mucins, and Alcian blue/periodic acid‐Schiff (AB/PAS) staining.In the respiratory bronchiole, two epithelial cell populations share the same basal lamina: one pseudostratified columnar with ciliated, secretory, and basal cells and the other predominantly simple cuboid with some interspersed flat (type I) cells. The columnar secretory cells show the ultrastructure of mucous cells. Light microscopically, they react with mucin antibodies and contain primarily periodatereactive acid mucins. The mucous cells are the distal secretory cells described by Clara (1937). The cuboid cells are identified as type II (precursor) cells based on ultrastructural criteria for embryonic type II cells (Ten Have‐Opbroek et al., 1988a, 1990a), including a cuboid cell shape, a large and roundish nucleus, rough and smooth endoplasmic reticulum (ER), osmiophilic multivesicular bodies, and dense bodies. These dense bodies in turn frequently exhibit—like those in embryonic type II cells—internal vesicles or lamellae, variability in size and shape, a specific relationship to ER and a widespread cytoplasmic distribution. Finally, the cuboid cells show a cytoplasmic staining pattern for SP‐A. The terminal bronchiole is lined by the columnar cell population.In the respiratory bronchiole, the columnar (bronchial) and cuboid (alveolar) cell populations occupy distinctly different zones (pulmonary artery zone versus remaining wall). The alveolar part of the respiratory bronchiole (called alveolar tubule) defines the proximal border of a true respiratory unit.
Spatial distribution of “Tissue‐Specific” antigens in the developing human heart and skeletal muscle. II. An immunohistochemical analysis of myosin heavy chain isoform expression patterns in the embryonic heart
Authors: Wessels A. , Vermeulen J. L. M. , Virágh S. Z. , Kálmán F. , Lamers W. H. , Moorman A. F. M. 
Published: February 2005

AbstractThe spatial distribution of α‐ and β‐myosin heavy chain isoforms (MHCs) was investigated immunohistochemically in the embryonic human heart between the 4th and the 8th week of development. The development of the overall MHC isoform expression pattern can be outlined as follows: (1) In all stages examined, β‐MHC is the predominant isoform in the ventricles and outflow tract (OFT), while α‐MHC is the main isoform in the atria. In addition, α‐MHC is also expressed in the ventricles at stage 14 and in the OFT from stage 14 to stage 19. This expression pattern is very reminiscent of that found in chicken and rat. (2) In the early embryonic stages the entire atrioventricular canal (AVC) wall expresses α‐MHC whereas only the lower part expresses β‐MHC. The separation of atria and ventricles by the fibrous annulus takes place at the ventricular margin of the AVC wall. Hence, the β‐MHC expressing part of the AVC wall, including the right atrioventricular ring bundle, is eventually incorporated in the atria. (3) In the late embryonic stages (approx. 8 weeks of development) areas of α‐MHC reappear in the ventricular myocardium, in particular in the subendocardial region at the top of the interventricular septum. These coexpressing cells are topographically related to the developing ventricular conduction system. (4) In the sinoatrial junction of all hearts examined α‐ and β‐MHC coexpressing cells are observed. In the older stages these cells are characteristically localized at the periphery of the SA node.
Deep‐etching immunogold replica electron microscopy of cytoskeletal elements in cultured hamster heart cells
Authors: Isobe Yuji , Hou Guan Ren , Lemanski Larry F. 
Published: February 2005

AbstractA procedure has been developed for the three‐dimensional immunoelectron microscopic localization of cytoskeletal filaments by a deep‐etching replica method in combination with immunogold labeling and/or myosin subfragment 1 (S1) decoration techniques. Neonatal hamster heart cells grown on glass coverslips were extracted with Triton X‐100 or physically permeabilized by breaking open the cell membranes. S1 decoration was performed on some specimens immediately after the permeabilization. After prefixation in formaldehyde, samples were immunostained with poly‐ or monoclonal antibodies to desmin or vimentin, and indirectly tagged with colloidal gold probes by the biotin‐streptavidin method. After postfixation with glutaraldehyde, tannic acid and osmium tetroxide, the cells were freeze‐etched and rotary‐replicated with platinum and carbon in a freeze‐fracture apparatus. Replicas were viewed with a transmission electron microscope using a tilting specimen stage to obtain stereo images. The procedure made it possible to identify the specific filaments within the complex cytoskeletal networks in cultured hamster heart muscle and nonmuscle cells at high resolution and in three dimensions. The method has advantages in its three‐dimensionality and feasibility to evaluate the data by comparing them with those obtained by alternative light microscopic methods. Details of the protocol and a description of the results of using three different antibodies are given.