bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning electron microscopy of the normal and denervated limb regenerate in the newt, Notophthalmus, including observations on embryonic amphibian limb‐bud mesenchyme and blastemas of fish‐fin regenerates
Authors: Geraudie Jacqueline , Singer Marcus 
Published: February 2005

AbstractThe present work deals with the morphology of normal and denervated early limb regenerates in the newt and compares them with early limbbud mesenchyme and blastemas of fish‐fin regenerates using the three‐dimensional properties of the SEM. It shows that blastemal cells are polymorphic, in contrast to those of the stump‐cell population, which are fairly homogeneous and from which blastema cells are said to arise by “dedifferentiation.” The appearance of the cells had not changed by two days following denervation even though previous biochemical studies have detected many changes in metabolism. Longterm denervation (7 days) did result in morphological changes. A comparison between well‐known cell type—myoblasts, Schwann cells, osteoblasts observed in vitro, limb‐bud mesenchyme and mesenchymatous fin blastema—was carried out in order to suggest explanations for the blastema‐cell polymorphism.
Cationized ferritin binding to anionic surfaces in normal and aminonucleoside nephrotic kidneys
Authors: Andrews Peter M. 
Published: February 2005

AbstractThe distribution and effects of polycationized ferritin (PCF) bound to anionic sites on living plasmalemmas and basal laminae of normal and puromycin aminonucleoside nephrotic (PAN) kidneys were studied using an in vitro model system. Immersion of normal glomeruli in physiological saline solutions containing low concentrations of PCF (0.01 to 0.1 mg/ml) for 10 seconds results in preferential binding of PCF to microvillous projections on the glomerular epithelium (i.e., podocytes). Exposure to higher concentrations of PCF (1.0 mg/ml) for 10 seconds results in several layers of PCF distributed evenly over the urinary aspect of epithelial podocytes. In these short treatment times, the thin slit diaphragms which span the filtration slits appear to be impermeable to PCF. Within several minutes after PCF treatment, ferritin is found within caveolae on the surface of epithelial podocytes and within numerous pinosomes and larger endocytic vesicles within these cells. Longer treatment with PCF results in the narrowing of filtration slit spaces and the formation of junctions between adjacent podocyte foot processes. Occurring coincident with these structural changes is a gradual accumulation of PCF in regular patches along the lamina rara externa (LRE) of the glomerular basement membrane. Loss of foot processes and accumulation of PCF in the LRE are prevented by treatment with either cytochalasin B (25 μg/ml), D (2 μg/ml) or incubation at low temperatures (0–4°C). When PCF‐coated glomeruli are incubated in PCF‐free media, the ferritin coat is shed from the free surfaces within 1/2 to 1 hour except at the tips and sides of microvillous projections. Pretreatment of normal glomeruli with neuraminidase or protamine sulfate results in a dramatic reduction in the binding of PCF to the glomerular epithelial free surface. Treatment of PAN glomeruli with PCF often results in patchlike distributions of PCF over the glomerular epithelial free surface. High concentrations of PCF (1.0 mg/ml) bind preferentially to microvillous projections on the parietal epithelial luminal surface and in distinct patchlike patterns along the basal laminae of parietal and tubular epithelial cells.
Lymphopoiesis in the chicken pineal gland
Authors: Cogburn L. A. , Glick B. 
Published: February 2005

AbstractPineal lymphoid development was studied in two breeds of chickens from hatching until sexual maturity. No lymphocytes were found in the pineal prior to 9 days of age (da). Lymphocytes migrate through the endothelium of venules into the pineal stroma. Lymphoid tissue reached its maximal accumulation in 32‐da pineal glands of both breeds. At this age, the New Hampshire (NH) breed had a larger proportion of lymphoid volume to total pineal volume (32%) than did pineal glands from White Leghorn (WL) chickens (18%). Averaged over the period 23 to 62 da, NH chickens (a heavy breed) had a lymphoid volume (0.753 mm3) that was about three times greater (P < 0.05) than that of the lighter WL breed (0.251 mm3). Lymphocytes are able to enter cerebrospinal fluid from lymphoid accumulations (LA) embedded in the choroid plexus by migrating between choroid ependymal cells. The 122‐da chickens typically lacked lymphoid tissue in the pineal gland with the exception of occasional LA contained in capsular tissue.Surgical bursectomy, thymectomy, or their combination at hatching followed with whole‐body irradiation (IR) at 24 hours postsurgery inhibited the initial influx of lymphocytes usually seen in 9‐da pineal glands. Also, these treatments prevented formation of germinal centers normally found in the pineal at 3 and 5 weeks and reduced total pineal volume at each age examined. However, pineal lymphoid volume of the surgical‐IR group did not differ from control‐IR chickens at either 3 or 5 weeks. Pineal glands from birds made agammaglobulinemic (bursa‐cell depleted) by cyclophosphamide treatment in ovo were devoid of germinal centers, although thin strands of lymphocytes were usually found along venous sinuses. These dissociation studies suggest that the normal expression of lymphoid tissue in the chicken pineal gland is dependent on the bursa and thymus. Furthermore, these observations indicate that the pineal gland should be considered a functional component of the chicken's lymphomyeloid complex.
Ultrastructure of the pineal gland of the fox
Authors: Karasek Michal , Hansen John T. 
Published: February 2005

AbstractThe ultrastructure of the pineal gland of the fox was examined and compared with that of other mammals. The pineal gland of the fox is composed of two different populations of pinealocytes (I and II). The pinealocytes I were distributed homogeneously throughout the parenchyma, while pinealocytes II were located generally near blood vessels. A Golgi apparatus, granular endo‐plasmic reticulum, mitochondria, lysosomes, centrioles, and cilia were present in both cell populations. A characteristic feature of pinealocytes I was the presence of dense‐core vesicles, presumably of Golgi origin; whereas glycogen deposits and pigment granules were common features of pinealocytes II. In addition to the pinealocytes, the parenchyma contained fibrous astrocytes. The capillaries of the pineal gland of the fox consisted of a nonfenestrated endothelium. Numerous nerve fibers, presumably adrenergic, were observed throughout the parenchyma.
Arterial branching in various parts of the cardiovascular system
Authors: Zamir M. , Brown N. 
Published: February 2005

AbstractAngiographic pictures of vascular beds in various parts of the cardiovascular system were analyzed to study the geometrical structure of arterial bifurcations. The sites of arterial bifurcations were enlarged individually, and measurements were made of the branching angles and branch diameters at each site. Results from various parts of the cardiovascular system of man, and some from rabbit and pig, were compared with each other. The measurements were also compared with “optimum” values of branching angles and branch diameters which have been predicted by various theoretical studies. In general the measurements were found to give support to the theoretical premise that branching angles and branch diameters in the cardiovascular system are dictated by certain optimality principles which aim to maximize the efficiency of the system in its fluid‐conducting function. In some parts of the system, however, the measured angles and diameters were found to be decidedly lower than those predicted by theory.
Development of intraosseous fibers of the mouse periodontium: A high‐voltage electron microscopic study
Authors: Johnson Roger B. , Low Frank N. 
Published: February 2005

AbstractDevelopment of intraosseous fibers was studied in mandibles of Swiss white mice, age 17 days to 45 days. Light microscopic (LM) and high‐voltage electron microscopic (HVEM) techniques were used. In LM, Wilder's reticular stain revealed intraosseous fibers throughout the interdental septum by day 17. Fibers were composed of unit collagen fibrils with abundant interfibrillar matrix. As development proceeded, fibers exhibited less interfibrillar matrix. Channels surrounding the intraosseous fibers became evident. Anchoring fibers attached the intraosseous fiber to bone. Fibroblasts appeared to be absent, suggesting that maintenance of the intraosseous fiber might be the function of the osteocyte. The presence of intraosseous fibers suggested a reevaluation of the fibrous attachment of teeth to bone. The concept of intraosseous fibers may simplify concepts of tooth movement and approximal drift.
Sensory components in the terminal innervation of the ovine cardiac conduction system
Authors: Munnell John F. 
Published: February 2005

AbstractNeuromuscular relationships in the cardiac conduction system of the ovine heart were studied by means of light and electron microscopy. Fluorescence microscopy was used to demonstrate the distribution of adrenergic nerves. Histochemical methods demonstrated sites of acetylcholinesterase and nonspecific cholinesterase activity at both light and electron microscopic levels. Surgical denervation was used in an attempt to support the identification of different types of nerve endings. A dense plexus of nerves strongly positive for acetylcholinesterase was present in all parts of the conduction system. Nonspecific cholinesterase was found to be limited to large nerve bundles which were presumed to be preganglionic. A dense plexus of adrenergic nerve fibers was identified in both the SA and AV nodes, but such fibers were very sparsely distributed along the AV bundle and its branches.On the basis of morphology as demonstrated by electron microscopy, three types of nerve endings or varicosities associated with the specialized cells of the conduction system were identified. Cholinergic endings, presumably post‐ganglionic parasympathetic, contained many nongranulated synaptic vesicles. Adrenergic or post‐ganglionic sympathetic endings or varicosities contained granulated synaptic vesicles. Axonal enlargements containing numerous mitochondria and varying numbers of pleomorphic dense bodies were identified as sensory endings on the basis of their morphologic similarity to such endings found elsewhere in the animal body. These were found in 22% of the blocks examined by electron microscopy, were present in all parts of the conduction tissue, and were acetylcholinesterase positive. They did not show obvious signs of degeneration following vagotomies or thoracic sympathectomy, suggesting the possibility that they were endings of neurons intrinsic to the heart. No signs of degeneration were noted in the endomysial plexus following vagotomy either proximal or distal to the distal (nodose) ganglion. Degeneration of small fibers of the plexus was noted following thoracic sympathectomy.This study provides evidence suggesting a significant sensory innervation to the cardiac conduction system, with the cell bodies of the sensory neurons located in or near the heart.
Localization of relaxin in endometrial gland cells of pregnant, lactating, and ovariectomized hormone‐treated guinea pigs
Authors: Pardo R. J. , Larkin L. H. 
Published: February 2005

AbstractUteri taken from guinea pigs in different stages of pregnancy and during lactation, as well as animals that had been ovariectomized and treated with hormones, were examined for relaxin with the peroxidase‐antiperoxidase (PAP) technique employing an antiserum produced against porcine relaxin. While relaxin was not detected in uteri of day 15 pregnant animals, small amounts were noted in a few endometrial glands in day 30 pregnant animals. Uteri from day 45, day 60, and late‐pregnant animals exhibited heavy amounts of relaxin; however, endometrial gland cells from lactating animals contained very little or no relaxin. Injections of estrogen and progesterone that brought a relaxation of the pelvic ligaments in ovariectomized guinea pigs also induced an accumulation of relaxin in the endometrial glands. Relaxin was not detected in nonendometrial portions of the uterus, endometrial stromal components, luminal surface epithelium, or uterine cervical glands. Extracts prepared from uteri of day 45, day 60, and late‐pregnant animals showed positive responses for relaxin in the mouse uterus bioassay.
The uterine progestational response in cats: Ultrastructural changes during chronic administration of progesterone to estradiol‐primed and nonprimed animals
Authors: Boomsma Robert A. , Verhagem Harold G. 
Published: February 2005

AbstractThe development of a progestational response in the glandular epithelium of the cat uterus was studied using electron microscopy and special glycogen staining techniques. In ovariectomized and adrenalectomized animals, the epithelial cells were low cuboidal and lacked an active secretory apparatus. Estradiol treatment induced hypertrophy and the formation of secretory cells which contained numerous profiles of RER, an enlarged Golgi apparatus and apical electron‐opaque secretory granules. The chronic administration of progesterone to estradiol‐primed animals resulted in antagonism of estradiol‐induced cytodifferentiation and the development of a progestational response in the glandular epithelium. After 1 day of estradiol plus progesterone treatment fewer secretory granules were observed, the RER was constricted, and the Golgi apparatus appeared less active; after 2 days, very few secretory granules were observed. Coincident with this antiestrogenic action, progesterone induced additional hypertrophy and the differentiation of cytoplasmic organelles associated with glycogen synthesis. Glycogen deposition occurred between days 2 and 4 of estradiol‐plus‐progesterone treatment. Numerous polyribosomes and circular profiles of membrane appeared to be associated with glycogen deposition. These membranes frequently had glycogen around their perimeter, and sometimes they were found embedded in large glycogen deposits. With continued progesterone treatment, glycogen processing occurred. The RER became extremely dilated, and a few halo granules were observed. Both the dilated RER and the halo granules appeared to be surrounding glycogen, and glycogen was frequently found bound by membrane as well as within the electron‐lucent portion of the halo granule. As glycogen processing continued, the glycogen deposits began to disappear, and some cells appeared to die. The remainder differentiated into shorter residual cells which, after 10–14 days, contained numerous halo granules and constricted RER. The chronic administration of progesterone to nonprimed ovariectomized and adrenalectomized animals resulted in a cytodifferentiation sequence similar to that in the estradiol‐primed animals, except that the response was delayed and was not as uniform between cells from the same animal. Thus, within each epithelial cell of the endometrial glands of the cat, the principal responses induced by progesterone in both estradiol‐primed and nonprimed animals were the synthesis, deposition, and eventual disappearance of glycogen.
Plasmalemmal vesicles (caveolae) of fibrous astrocytes of the cat optic nerve
Authors: Massa Paul T. 
Published: February 2005

AbstractPlasmalemmal vesicles (caveolae) are described in fibrous astrocytes of the cat optic nerve. In thin sections, astrocytic caveolae appear as flask‐shaped invaginations of the plasma membrane with a 60‐nm lumen that communicates with the extracellular space through a 35‐nm stoma. Occasional bilobed caveolae occur. The caveolae extend approximately 85 nm into the astrocytic cytoplasm and are often embedded within a granular or filamentous ectoplasmic substance connected by 4–8‐nm filament bridges to underlying bundles of 10‐nm glial filaments. In freeze‐fracture replicas, the caveolar stomata appear as dimples on the P face and as craters on the E face, often arranged in hexagonal or linear arrays and spaced at a center‐to‐center distance of 110–130 nm. The caveolar membrane is apparently particle‐free. Fibrous astrocytes related to the connective‐tissue septa of the optic nerve show different densities of caveolae on different areas of their plasma membranes. Plasma membranes apposing a basal lamina have few caveolae, whereas membranes not apposed to the basal lamina but to other astrocytic membranes have up to 17 caveolae/μm2. Caveolae also occur on astrocytic plasma membranes apposed to myelin sheaths. Possible functions of the astrocytic caveolae are discussed in the light of plasmalemmal properties of other types of caveolae‐bearing cells.
Fetal and neonatal rat intestinal capillaries: Permeability to carbon, ferritin, hemoglobin, and myoglobin
Authors: Milici Anthony J. , Bankston Patrick W. 
Published: February 2005

AbstractThe function of the mural components involved in vascular exchange (pinocytotic vesicles, fenestrations, intercellular junctions, and the basal lamina) was assessed by intravascular injection of tracers (carbon, carbon plus histamine, ferritin, hemoglobin, and myoglobin) on separate gestational days in fetal and neonatal rat intestinal capillaries. The continuous capillaries present through day 17 of gestation were impermeable, even at junctions, to all the tracers within the maximum circulation time studied (3 minutes). Most of the luminal pinocytotic vesicles were labeled within 3 minutes with myoglobin (3.3‐nm diameter) or hemoglobin (5.5‐nm diameter), while only occasional vesicles contained ferritin (11‐nm diameter) and none contained carbon (25–50nm diameter). Even though luminal pinocytotic vesicles contained the smaller tracers, no vesicular transport and discharge were ever seen. The fenestrated vessels present from day 18 of gestation allowed a rapid extravasation of ferritin and hemoglobin via diaphragmed fenestrations. At no time period did extravasation of carbon take place, nor did the carbon plus histamine solution induce vascular leakage. Once a tracer gained access to the extravascular space, the developing basal lamina did not seem to retard its movement.
Structure, blood supply, and lymphatic vessels of the sheep's visceral pleura
Authors: Albertine Kurt H. , Wiener‐Kronish Jeanine P. , Roos Philip J. , Staub Norman C. 
Published: February 2005

AbstractWe investigated the morphology of the visceral pleura of 36 sheep, using macroscopic, histologic, and ultrastructural approaches to quantify regional pleural thickness, blood supply, and lymphatic drainage, including the pulmonary ligament and hilar lymphatic distributions. Pleural thickness increased caudally and dorsally, such that the costal pleura of the caudal lobes had a mean minimum pleural thickness of 83 μm. The blood supply to the entire visceral pleura came exclusively from the bronchial arteries. Lymph vessels formed an extensive plexus throughout the serous membrane of all lobes. Trunk lymphatics (> 100 μm diameter) had a density of about 2/cm of pleural length on all lobar surfaces except for the cranial and middle lobes, where their density on the costal surfaces was ≤ 1/cm. Pleural trunk lymphatics coursed to the pulmonary ligaments and to the hilum on their way to regional lymph nodes. At the hilum they anastomose with intrapulmonary lymphatic trunks. The principal lymph nodes to receive pulmonary lymph were the caudal mediastinal node and tracheobronchial nodes. The visceral pleura of sheep is thick, showing considerable regional diversity in morphology.
Leydig cell development of pig testis in the early fetal period: An ultrastructural study
Authors: van Vorstenbosch C. J. A. H. V. , Colenbrander B. , Wensing C. J. G. 
Published: February 2005

AbstractLeydig cell development in the pig testis occurs in three periods (an early fetal, the perinatal period, and the period from puberty onward). The earliest of these periods was investigated ultrastructurally. The early fetal period starts immediately after gonadal differentiation, approximately 27 days postcoitum (p.c.), and finishes at about 60 days postcoitum. Dates of observation were 35, 52, and 62 days p.c. At 42 days p.c. some animals were decapitated.Leydig cells at 35 days p.c. are characterized by an oval nucleus, vesicular or branched tubular smooth endoplasmic reticulum (SER), and a small quantity of rough endoplasmic reticulum (RER). The RER has two forms: a short and a long profile. The latter is closely coupled with mitochondria. The mitochondria mostly have tubular cristae. From 52 days p.c. onward the degree of coupling lessens, and it vanishes at 62 days p.c. At 52 and 62 days p.c. a very large amount of 10 nm filaments and a slight decrease in SER can be observed. The SER now has a branched tubular form, and the presence of polygonal dense bodies is also characteristic.Decapitation does not disturb normal development of the Leydig cells in the observation period. No obvious differences from controls can be observed.
Axonal interactions with connective tissue and glial substrata during optic nerve regeneration in Xenopus larvae and adults
Authors: Bohn R. C. , Reier P. J. , Sourbeer E. B. 
Published: February 2005

AbstractAxonal elongation through connective tissue and glial environments was compared following resection of the optic nerves in Xenopus tadpoles and frogs. During initial stages of fiber outgrowth, axons encountered connective‐tissue matrices of varying degrees of complexity in the ablation gaps. Many of the neuritic sprouts were randomly directed after leaving the retinal stump, and a neuroma‐like swelling ultimately formed at the cut edge. Although a large number of axons managed to traverse the lesion and associate with the cranial stump, many other fibers were less appropriately directed, especially in the frog where a greater infiltration of dense collagen occurred between the separated segments of the optic nerve. Axons often deviated from their cranially oriented pattern of outgrowth after entering the lesion and invaded surrounding extraocular muscles; others advanced along neighboring blood vessels and cranial nerve branches. In more extreme circumstances, fibers were completely misdirected at the cut end of the retinal stump and ultimately extended adjacent to the retinal segment back toward the eye. A more organized pattern of axonal elongation was observed in the presence of the glial substratum of the central stump, and growth cones appeared to associate preferentially with astrocyte endfeet in both tadpoles and frogs. These observations show that axons in the regenerating optic nerve of the amphibian can interact with a variety of cells and tissues and that the general direction of their outgrowth, at least in more peripheral regions of the visual pathway, appears to be dependent upon the orientation and, possibly, molecular properties of the terrain which they contact. In general, the basic environmental factors which either foster or impede axonal elongation in this regenerating system appear analogous to those influencing fiber outgrowth during regeneration in the peripheral nervous system of various species.