bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of the harderian gland in the Syrian golden hamster (Mesocricetus auratus): A light and electron microscopic study
Authors: López José M. , Tolivia Jorge , Alvarez‐Uría Manuel 
Published: February 2005

AbstractThe main objective of the present investigation was to study the morphological and chronological aspects of the development of the Harderian gland in the Syrian golden hamster. Tissues were obtained from male and female hamsters at days 1,3,5,7,10,12,15,17,20,27,37,46, and 90 after birth and processed for light and transmission electron microscopy. The present observations indicate that a well‐defined temporal sequence in microscopic and ultrastructural modification is recognizable in the development of the hamster Harderian gland. Four stages of development were proposed. Between days 1–5 (first stage), the gland shows characteristics of an immature structure. The glandular cells contain many free ribosomes, few and small organelles, and large irregular‐shape nuclei. Between days 7–17 (second stage), there is a marked increase of organelles involved in synthesis and secretion. The gland begins the secretion of lipids and porphyrins, but no morphological differences between male and female glands are observed. Between days 20–36 (third stage), the morphological differences between the two sexes appear and progressively develop. In 45‐day‐old hamsters, the Harderian gland possesses the structural characteristics of adult glands, and further developmental changes are essentially quantitative in nature (fourth stage). At all stages of development, the population of secretory cells has a uniform appearance. The morphological results are discussed as well as the possible relationship of this temporal sequence with hormonal changes. © 1992 Wiley‐Liss, Inc.
Bone and cartilage resorption in relation to tooth development in the anterior part of the mandible in cichlid fish: A light and TEM study
Authors: Huysseune Ann , Sire Jean‐Yves 
Published: February 2005

AbstractThis paper presents ultrastructural features of the contact region between particular tooth germs and Meckel's cartilage prior to, during, and after initial resorption of the perichondral bone and of the cartilage in the cichlids Hemichromis bimaculatus and Astatotilapia burtoni. Imminent resorption opposite such teeth is announced by the presence, in this region, of a particular cell type, considered to be a stage in the cytodifferentiation of osteoclasts. Slightly later, an osteoclast with typical ruffled border is seen to open a fenestra in the perichondral bone which surrounds Meckel's cartilage. Although the action of the osteoclast is directed primarily towards the bone, it may also affect, to a much lesser extent, the underlying uncalcified cartilage. Typically, fibroblast‐like cells invade the resorption cavity along with the osteoclast; the tooth germ soon follows. Capillaries are seen to invade the cartilage only at a later stage when a large cavity has been established. It is proposed that the fibroblast‐like cells may have a dual function: degradation of cartilage and deposition of new bone. Although these processes are normally limited to the area surrounding tooth germs at specific loci, tooth germs in other positions may sometimes be seen to invade the cartilage. They do so either passively, because of the existence of such a cavity, or as a result of their own resorption‐inducing activity. Whatever the mechanism, attachment bone is being deposited within the erosion cavity and on the surface of the exposed perichondral bone. The stimuli possibly eliciting resorption of Meckel's cartilage are discussed. It is hypothesized that pressure exerted by the growing tooth germ may stimulate the osteoblasts covering the bone surface and, in this way, provoke osteoclastic bone resorption. © 1992 Wiley‐Liss, Inc.
Immobilization‐induced muscle atrophy is not reversed by lengthening the muscle
Authors: Maxwell L. C. , Enwemeka C. S. 
Published: February 2005

AbstractIn clinical practice, repaired tendocalcaneus (Achilles tendon) ruptures are often protected in immobilization casts for 4 weeks in the fully plantar flexed position and for up to another 4 weeks after returining the ankle to joint neutral. Moderate to severe muscle atrophy occurs within 4 weeks of immobilization in plantar flexion, but it is not known if this atrophy is minimized or reversed following restoration of joint neutral position. We tested the hypothesis that the extent of atrophy could be reduced by returning the ankle to joint neutral after 4 weeks of immobilization. Eighteen rabbits were anesthetized, and their right hindlimbs were casted with the knee flexed 90° and the ankle fully planter flexed. Three animals each were studied after 3, 4, 6, or 8 weeks of immobilization. After 4 weeks of immobilization, the immobilization casts of the remaining six rabbits were modified to reture the ankle to joint neutral for another 2 or 4 weeks. For muscle studies, the animals were anesthetized, and the soleus (SOL), plantaris (PLN), and gastrocnemius (GST) muscles were removed and weighed; the SOL and PLN were quick frozen and processed for histochemical fiber typing and fiber cross‐sectional area measurement. All three muscles showed significantly reduced muscle weight to body weight ratios after 3 weeks of immobilization. SOL was the most affected, and GST was least affected. There was no significant further atrophy through 8 weeks of immobilization. The atrophy corrolated with a significant reduction of mean fiber area (MFA) for Types I, IIo, and IIc fibers in SOL and PLN. In PLN, Type IIg fiber area was not significantly reduced. MFAs of fibers of SOL and PLN muscles that were lengthened by returning to ankle joint neutral for 2 or 4 weeks were not different from those from those of limbs kept at planter flexion for 6 or 8 weeks. These data indicate that atrophy had reached a near‐maximal extent within 4 weeks and that subsequent lengthening of the muscles did not reverse the atrophy. © 1992 Wiley‐Liss, Inc.
Effect of cyproterone acetate on structure and function of rhesus monkey reproductive organs
Authors: Kaur Jagdeep , Ramakrishnan P. R. , Rajalakshmi M. 
Published: February 2005

AbstractA low dose of Cyproterone acetate (CPA; 1 mg/kg body weight/day for 70 days) was administered to adult male rhesus monkeys to assess its effects on testicular and epididymal structure and function in a nonhuman primate species. CPA caused extensive degenerative changes in morphology of seminiferous, efferent duct, and epididymal epithelia, including decrease in diameter of seminiferous and epididymal tubules and their lumen, height of epididymal epithelium, and an increase in intertubular connective tissue. The protein profile of spermatozoa showed alterations during their epididymal transit in control and CPA‐treated monkeys. In CPA‐treated animals, 19 polypeptides were acquired and nine were eliminated during epididymal transit in contrast to acquisition of 12 and loss of 14 polypeptides in control animals. Treatment with CPA also resulted in the appearance of 14 new polypeptides in epididymal cytosol and luminal fluid, probably of lysosomal origin. The protein pattern of caput and cauda epididymal tubule cytosol, maintained in organ culture and exposed to 100 μM CPA for 3 days, showed absence of eight polypeptides.These results indicate that even at the low dose used in this study, CPA has caused spermatogenic arrest, degenerative changes in the epididymal structure, and alterations in epididymal and sperm protein profile. Suppression of serum testosterone levels indicates the need for androgen supplementation if CPA is to be used for male contraception. © 1992 Wiley‐Liss, Inc.
Transplatation of fetal mouse colon under the kidney capsule of an adult mouse: A model for the study of colonic development
Authors: Gabriel Anastasia , Robinson Peter M. , Whitehead Robert H. 
Published: February 2005

AbstractFourteen‐day fetal mouse colon was transplanted under the kidney capsule of an adult mouse to determine whether this system could be used as a model of embryonic colonic development. The 14‐day fetal colon was transplanted and left for a period of 7 days. Comparisons of the normal one day postnatal colon and the transplanted colon were made morphologically and morphometrically. It was found that the transplanted fetal colon resembled its postnatal counterpart with respect to morphology; the cell types seen in the transplanted colon were similar to those observed in the in situ colon of the same age. However, morphometric analysis showed that the transplanted colon was significantly smaller than its postnatal counterpart, suggesting that conditions in the host were not optimal to support the full growth of the colon. In spite of this, it appears that the fetal colon can differentiate normally under the kidney capsule and this model can be used to study both epithelial‐mesenchymal interactions and the role of hormones in fetal colonic development.© Willey‐Liss, Inc.
Coronary artery development in the chick: Origin and deployment of smooth muscle cells, and the effects of neural crest ablation
Authors: Hood Lisa C. , Rosenquist Thomas H. 
Published: February 2005

AbstractPrevious studies of coronary artery ontogeny have stressed early development and therefore have dwelt mainly upon the origin of the endothelium of the nascent coronary artery stem. This study has analyzed the ontogeny of the vascular smooth muscle cells (VSMC) in the coronary arteries of the domestic chicken, by establishing the timing and deployment of smooth muscle alpha‐actin (SMAA). Anti‐SMAA was applied to sections of normal embryos, and to sections of experimental embryos that had undergone surgical ablation of the neural crest over somites 1–3. The results show an orderly symmetrical deployment of SMAA in control coronary arteries. SMAA was expressed significantly earlier in the coronary artery VSMC compared with those of the cardiac outflow vessels; this early expression may indicate a unique responsiveness to induction of the smooth muscle phenotype. The normal orderly development of coronary artery VSMC was dependent upon the presence of the neural crest, and therefor was disrupted in the experimental embryos whose neural crest was ablated.© Willey‐Liss, Inc.
Effects of prostaglandin inhibition on the bone activities associated with the spontaneous drift of molar teeth in the rat
Authors: Lasfargues J. J. , Saffar J. L. 
Published: February 2005

AbstractLittle is known about local bone regulation that enables spontaneous molar tooth drift. In this study the role of prostaglandins (PGs) were investigated in the rat by inhibiting PG‐synthesis with indomethacin (7 mg/kg/d). Untreated animals were killed at the start of the experiment, while treated ones were killed after 3, 7, or 14 days of treatment. Mandibles were processed for histomorphometry without demineralization. Changes in osteoclasts and extent of the different steps of the bone remodeling sequence (resorption, reversal, and formation) were assessed along the remodeling side of the socket of the buccal root of the first molar. The total number of osteoclasts decreased after 7 days of PG inhibition (P<0.01 vs controls) and then partially recovered. This change was due to a sharp decrease in active cells on day 7 (P<0.01), while inactive cells remained unchanged throughout the experimental period. The extent of resorption fell on day 7 (P<0.01) and then recovered almost to the control level on day 14. Reversal at first increased insignificantly and thereafter decreased (P<0.02) for the remaining 7 days. Formation was modified only on day 14; at that time it had doubled compared with controls. These results show that PGs are involved in the local regulation of bone remodeling accompanying tooth drift. Resorption inhibition was partial, indicating that other factors participate with PGs in this regulation; in addition, the trend to recovery observed at the end of the experimental period suggests that these factors can take over from PGs to achieve the necessary remodeling of the socket.© Willey‐Liss, Inc.
Elastic fibers in the duct system of the rat submandibular salivary gland
Authors: Lorber Mortimer 
Published: February 2005

AbstractThe submandibular salivary gland originates from the floor of the mouth whose mucosa contains elastic fibers. Therefore, such fibers were sought in the duct system of the derivative organ. In adult rats, light microscopy has indeed revealed fine, circumferential, elastic fibers near the basement membrane of the duct epithelium. In the larger extralobular ducts, they were separated from several layers of longitudinal elastic fibers by a capillary‐rich zone sparse in elastic fibers except for fine angular ones. More peripherally, larger angular‐appearing fibers were frequently present near the submandibular parasympathetic ganglia in the duct wall. As duct diameter decreased, elastic fiber size and number diminished. Intralobularly, the smaller striated ducts, granular and intercalated ducts, and acini generally lacked such fibers. Electron microscopy of the extraglandular portion of the main duct revealed fibrils extending from both fibroblasts and elastic fibers that were close to the epithelium. Microfibrils coursed from them toward the lamina densa. Anchoring filaments joined the lamina densa to the basal plasma membrane of the epithelium. Elastic fibers also appeared to connect to both capillaries and collagen via finer intermediate structures. These associations might permit dynamic interactions of fibroblasts, fibers, smaller fibrillar components, vasa, and the duct epithelium. This interplay could occur during feeding and grooming when tongue protrusion and neck extension stretch the submandibular duct and the gland itself. As a result, the tensile forces engendered could modify cell geometry and the calibers of the larger ducts' lumens and intercellular spaces, thus affecting the flow and composition of salivary secretion.© Willey‐Liss, Inc.
Structural analysis of fetal rat lung development
Authors: Burri Peter H. , Moschopulos Michael 
Published: February 2005

AbstractThe primary aim of this morphological investigation was to elaborate a concept allowing us to coherently define reference spaces for morphometric analysis of fetal lung development. Beyond this quantitative goal, morphological analysis of cell types, definition of compartments, and reflection about the prospective fate of their constitutents provided per se new insights into the developmental processes.Lungs of rat fetuses aged 17–23 days and newborns aged 20 hours were fixed with an osmium tetroxide and glutaraldehyde mixture and their volume determined. Left lungs were embedded in Epon and investigated by light and electron microscopy. The right lung of one animal per group was embedded in methacrylate and step sections obtained to precisely locate the airways within the mesenchyme.The various cell types, their topographical relationships, and their morphological alterations with ongoing development were analyzed with regard to their prospective potentials of differentiation.The developing lung could be partitioned into four zones further subdivided into defined compartments. Zone I forms a superficial mantle around the lobes and the future acini. Consisting of primitive mesenchymal cells, it represents a zone of growth which disappears with the onset of the saccular stage. Zone II is mainly a zone of differentiation. Its interstitium stains intensely due to a dense population of dark cells. Up to gestational day 19, zone II contains future conductive airways with their vessels. After day 21, it comprises the whole prospective gas exchange region. Zones III and IV contain the elements of the airway tree and vascular system, zone IV corresponding to the most proximal generations with an adventitial layer. For all differentiation processes, a centrifugal directionality is manifested.© Willey‐Liss, Inc.
Ultrastructure and immunocytochemistry of the neuroepithelial bodies in the lung of the tiger salamander, Ambystoma tigrinum (Urodela, amphibia)
Authors: Goniakowska‐Witalińska L. , Lauweryns J. M. , Zaccone G. , Fasulo S. , Tagliafierro G. 
Published: February 2005

AbstractLight and electron microscopy of the lungs of Ambystoma tigrinum (Urodela) revealed a relatively complex pattern of the neuroendocrine (NE) cells. In the apical parts of smaller septa single NE cells not associated with nerve fibres were covered and surrounded by pneumocytes. The larger septa possessed small areas of ciliated epithelium, in which the NE cells were grouped in a form of neuroepithelial bodies (NEB) consisting of 3–5 cells and covered by goblet cells. NE cells possessed a large nucleus with patches of condensed chromatin, clear cytoplasm, and membrane‐bound vesicles of variable morphology and size, of these dense core vesicles (DCV) ranged from 70–140 nm, while rarely the larger ones exhibited a diameter of 300–600 nm. In some NEB a second type of NE cells was observed for the first time in an amphibian species: these cells communicated with the air space and exhibited on their surface microvilli and a single modified cilium with a 8+1 microtubule arrangement. Their cytoplasm contained two types of DCV: dense core granules with a diameter of 140–260 nm and vesicles 320–700 nm in diameter with a moderately electron dense interior. The NEB were associated with intracorpuscular, sensory nerve terminals morphologically afferent and efferent. By immunocytochemistry, the NE cells revealed the presence of serotonin, met‐en‐kephalin, and leu‐enkephalin. A paracrine and chemoreceptor role is proposed for NEB of Ambystoma tigrinum.© Willey‐Liss, Inc.
Distribution of p21ras in postimplantation rat embryos
Authors: Brewer Linda M. , Brown Nigel A. 
Published: February 2005

AbstractExpression of ras cellular oncogenes during the early postimplantation period in the rat was investigated using immunohistochemistry to p21ras was used in an indirect avidin‐biotin‐peroxidase (ABC) technique. Positive staining indicating the presence of p21ras was found in embryos from 6.5 to 12 days embryonic age. In early egg cylinders (6.5 days), positive staining for p21ras was observed on the ectoplacental cone, primitive ectoderm and trophectoderm, while primitive endoderm and parietal endoderm appeared paler. In later egg cylinder stages (7.5 days), strong positive staining was observed in the primitive embryonic ectoderm and ectoplacental cone, but parietal and visceral endoderm still appeared to be devoid of positive staining. As development proceeded during primitive streak stages, the visceral and parietal endoderm became positively stained. By 10 days, all tissues appeared to be positive for p21ras, with strong staining appearing in the heart and neural elements. Therefore, p21ras does not appear to be ubiquitous in the rat conceptus prior to gastrulation, but shows differential distribution, appearing later in endodermal derivatives. Possibly p21ras is involved in determination of the ectodermal and endodermal lineages.© Willey‐Liss, Inc.
An extracellular matrix infrastructure provides support for murine secondary palatal shelf remodelling
Authors: Morris‐Wiman J. , Brinkley L. 
Published: February 2005

AbstractA cricial part of secondary palate morphogenesis is the movement of the palatal shelves from an initial vertical position on either side of the tongue to a final horizontal one above it to achieve palate closure. The immunocytochemical localization of extracellular matrix (ECM) molecules in the palatal shelf during this remodelling and reorientation revealed the existence of an ECM infrastructure within the mesenchyme. The major components of this infrastructure were collagen III, fibronectin, and hyaluronate (HA). With remodelling, HA's domain within the mesenchyme was expanded, whereas those of fibronectin and collagen III became more circumscribed. The expansion of an HA‐rich matrix within the mesenchyme is thought to be crucial for palatal reorientation. The results of this study suggest that, as this expansion occurs, it is modulated by collagen and fibronectin components of the ECM infrastructure. Prior to shelf remodelling, this infrastructure may be anchored by a specialized region of the midoral epithelial‐mesenchymal interface and the subjacent mesenchyme which is characterized by the unique distribution of collagen III, fibronectin, and tenascin. The midoral palatal epithelium also may play a role in directing shelf expansion. This epithelial region undergoes changes in cell packing and epithelial cell layering that correlate with shelf remodelling. These changes occur concomitantly with changes in the expression of collagen III, collagen IV, and laminin within the underlying basement membrane. The localization and patterning of tenascin within the developing palate suggests that it not only contributes to the postulated anchoring structure of the midoral epithelial‐mesenchymal region, but also plays a role in the determining the fate of the medial edge epithelial cells during the final stage of palate closure.© Willey‐Liss, Inc.
Accuracy and precision of computerized models of the anterior cranial base in young mice
Authors: Lozanoff Scott 
Published: February 2005

AbstractThe quantitative analysis of craniofacial growth in experimental animals relies on computerized reconstructions in order to measure changes in form. The purpose of this study was to determine the validity of computerized three‐dimensional models of the anterior cranial base in mice. Ten 1‐day‐old non‐littermates were collected and the anterior cranial base was dissected free from surrounding connective tissues. Eleven measurements were recorded from these cartilages. Twenty developmentally equivalent mice were collected and fixed with either glutaraldehyde or formalin and the anterior cranial base from each specimen was subjected to computerized reconstruction. The corresponding 11 measurements were recorded from these models. Results showed that the measurements recorded from the computerized models were not significantly different from those recorded directly from the actual anterior cranial bases. Therefore, the reconstructions were considered accurate. An analysis of the coefficients of error revealed that measurements derived from the computerized models were significantly more precise than those recorded directly from the actual tissue. The computerized three‐dimensional reconstruction method provides accurate and precise models of the anterior cranial base in young mice.© Willey‐Liss, Inc.