摘要:

AbstractThe development of the functional components of the myocardial capillary wall was characterized by time‐course studies of transendothelial transport of intravascularly injected probes of graded size from 16 days of gestation in the fetal rat to seven days postpartum. Despite the morphological changes occurring in the developing endothelial cells, the interaction of the probes was similar throughout the developmental period studied. The carbon particles were retained within the capillary lumina without any association with interendothelial junctions or with plasma‐lemmal vesicles. Carbon also was associated with coated vesicles. In contrast to carbon, ferritin was localized sequentially, over 60 sec of circulation, in plasmalemmal vesicles on the lumenal surface, in the cytoplasm, and on the ablumenal surface of the endothelial cells as well as in the interstitial space. Ferritin was located also in coated pits and vesicles and, after 90 sec of circulation, in multivesicular bodies. Within 30 sec of circulation, reaction product of myoglobin was located in plasmalemmal vesicles, coated vesicles, and transendothelial cell channels. Also within 30 sec, myoglobin partially filled the interendothelial space from the capillary lumina to the level of the tight junction. At all developmental ages studied, the interendothelial cell junctions appeared structurally tight and were impermeable to all of the probes. Once ferritin or myoglobin had reached the ablumenal space, the basal lamina did not appear to restrain the passage of the probes. Plasmalemmal vesicles are the capillary structures which transendothelially transport ferritin and myo‐globin in developing myocardial capill

ISSN:0002-9106    

DOI:10.1002/aja.1001800402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMesenchymal derivatives of the neural crest contribute to the connective tissues and blood vessels of the pharyngeal arches, and participate in the septation of the outflow tract of the heart. The present study was designed to determine the nature and timing of alterations in the development of the heart and arch arteries subsequent to diminished neural crest contributions. The neural crest contributing to the three caudalmost pharyngeal arches was ablated bilaterally in chick embryos and compared with sham or unoper‐ated controls. Heart development was studied by scanning electron microscopy. Arch artery development was studied microscopically after intravascular injection of India ink and clearing of the specimen. Neural crest ablation caused morphological changes in most hearts. Hearts in experimental animals commonly were elongate and were subject to inappropriate development of ventricular and atrial areas. A surgical effect delayed the disappearance of arch arteries one and two, and removal of neural crest produced an additional delay. Neural crest ablation caused failure of arch arteries three, four (right), and six to develop to the proper size in some animals. Survival of those whose sixth arch arteries achieved the proper size caused group measurements to reach normal values again by stage 32. Closure of arch arteries in some animals and maintenance in others produced greater variability in experimental animals than in controls. It is significant that heart morphology was altered before septation of the outflow tract normally occurs. This indicates at the least that another factor, such as altered blood flow, contributes to the abnormal development. Altered flow may result from changes in pharyngeal arch mesenchyme and arch artery endotheliu

ISSN:0002-9106    

DOI:10.1002/aja.1001800403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis study investigated sphincter‐body differences in neuronal density and morphometry between the esophageal sphincter and body with a view to determining whether previously reported differences are authentic. The anatomical limits of the opossum lower esophageal sphincter were correlated with its physiological behavior by manometric demarcation. Following this, peeled whole mounts and paraffin and cryosections were used to study the morphology and morphometry of the esophageal myenteric plexus. Thirty animals were used and seven quantitated. The plexus of the esophageal body was located as usual in a plane between the longitudinal and circular muscle, which coincided with the plane of cleavage when these muscle layers were peeled apart for studying the plexus in whole mounts. In contrast, the plexus was located in several planes in the lower esophageal sphincter, Which had no cleavage plane. Therefore, peeling the sphincter removes neurons and yields falsely low counts, making peel preparations of this region unsuitable for neuronal quantitation. In paraffin sections, the neuron density in the esophageal body 7 cm above the sphincter was 6,353±850/cm2but decreased significantly to 2,254±353/cm2at the 1‐cm segment. In the lower esophageal 8,530±1,606/cm2. Flash‐frozen cryosections, which produced neuronal morphology similar to the in vivo condition, showed that there was no difference in neuronal size between esophageal body and sphincter. These studies show that atypical myenteric plexus localization causes spuriously low neuronal counts reported in the lower esophageal sphincter and that reported neuronal size differences are technique

ISSN:0002-9106    

DOI:10.1002/aja.1001800404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMorphological and quantitative studies were made on serotonin‐containing paraneurons throughout the lower urinary tract in male and female dogs. Using an anti‐serotonin antiserum, the cells were consistently demonstrated to be dispersed in the epithelium from the vesico‐urethral junction to the external urethral ostium. They occurred most frequently in the urethra proximal to the urogenital diaphragm in both sexes. The total number of the serotonin‐immunoreactive cells in the urethra, was estimated to be 36.2 × 104(SD 9.9 × 104in the male (n=3) and 15.6 × 1042.1 × 104) in the female (n=3). Besides the urethra, the prostate and vaginal vestibule contained several sero‐tonin‐immunoreactive cells. The urethral serotonin cells were basically bipolar basal‐granulated cells that extended the basal cytoplasm too the basement membrane and reached the lumen with an apical process. Modified cell shapes were, however, also frequent, and included bifurcated apical and/or basal processes or a laterally directed basal process. Occasional serotonin cells possessed a threadlike basal process with varicos‐ities and a terminal bouton, reminiscent of a neuronal process. Immunoreactivity for chromogranin A, a carrier protein common to endocrine paraneurons, was demonstrated in all of the urethral serotonin cells. The chromogranin A‐immunoreactive granules accumulated more densely in the basal and perinuclear regions of the cell. It is hypothesized that the serotonin‐immu‐nopositive paraneurons may receive chemical and/or physical information from urine and, in response to it, secrete serotonin which presumably causes the contraction of the m

ISSN:0002-9106    

DOI:10.1002/aja.1001800405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAlteration in posture was examined following foreleg amputation in rats. After the surgical induction of bipedal stance, a detailed, quantified, and longitudinal assessment of rat posture and the amount of time spent in the upright stance was undertaken.An experimental group of rats had both forelimbs amputated. A group of unaltered quadrupedal rats served as controls. A standardized series of photographs of altered and control rats was taken. Postural differences between the two groups of rats were analyzed through photographic analysis of their profiles in upright and in crouched positions.Analysis of the photographs showed that the percentage of rats assuming upright posture did not differ between the experimental and control groups. Foreleg amputation forced the rats to adopt an altered posture, but did not result in habitual assumption of upright stance to a greater degree than that of controls. Adaptation to bipedalism was marked by a tucking of the hindlimbs under the body, and a flexure of the vertebral column and the head.

ISSN:0002-9106    

DOI:10.1002/aja.1001800406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe objective of this study was to determine how long myogenic cells can survive in the central ischemic zone of early free muscle grafts in the rat. The study was conducted on free grafts of a large (rectus femoris) and a small (extensor digitorum lon‐gus) muscle. At times ranging from zero hr to five days post‐grafting, the central zones were isolated, minced, and implanted under the back skin of mice. After five days the minces were removed and examined histologically for the presence of rat myotubes, which should form only in minces that contain viable myogenic cells. The results show that myogenic cells survive two to four hr in the ischemic centers of the large rectus femoris grafts; after longer post‐grafting intervals, rat myotubes did not arise in central zone minces. In grafts of small muscles, myotubes consistently appeared in central zone minces. Since the formerly ischemic central areas of rectus muscle grafts are ultimately replaced by regenerating muscle fibers, we conclude that these regenerating muscle fibers are derived from precursor cells located outside of the ischemic

ISSN:0002-9106    

DOI:10.1002/aja.1001800407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractTo study the evolution of pericardial inflammation, we have developed a model of pericarditis in sheep by surgically injecting heat‐killed staphy‐lococci and Freund's adjuvant into the pericardial cavity under sterile conditions. The pericarditis evolved through the following phases: (1) inflammatory response, (2) mesothelial cell injury and desquamation, and (3) fibrotic phase. At 3–24 hr there was increased microvascular permeability, which resulted in the exudation of fluid, neutrophils, macrophages, ami fibrin into the pericardial cavity and the pericardial intersti‐tium. By 72 hr, large numbers of inflammatory cells were aggregated on the mesothelial surfaces and dispersed throughout the pericardial cavity, either as free‐floating cells or located between strands of fibrin. At 6 days, fibrinolysis was apparent along the mesothelial surfaces; and newly formed collagen fibrils were deposited throughout the interstitial spaces and among the aggregated cells. These fibrils provided a matrix for the growth of new blood and lymphatic vessels into new connective tissue on both parietal and visceral pericardial surfaces. At 2 weeks, intrapericardial fibrosis had produced focal adhesions between the pericardial surfaces. By 1 month, extensive areas of the pericardial cavity were obliterated. By 9 months, there was a marked reduction in the numbers of cells and blood vessels and increased deposition of collagen and elastic fibers. The intrapericardial injection of heat‐killed staphylococci and adjuvant provides a reproducible animal model to study the time course of pericardial i

ISSN:0002-9106    

DOI:10.1002/aja.1001800408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractIn order to understand the process of anoine formation on the ganoid scales, scale regener‐ation has been studied to overcome the lack of a growth cries of scale ontogeny. Seven stages of ganoid scale regeneration have been defined over a period of five months in the polypterid fish Calamoichthys calabariits. The study has been carried out using transmission electron microscopic techniques. After wound healing and differentiation of the osseous basal plate, a layer of vascular dentin is deposited at the upper surface of he basal plate owing to the presence there of odonto‐ilasts closely applied to the dentin. When these cells nove away, a close contact is then established between he stratified epidermis and the regenerating scale. Nu‐nerous alterations of the epidermal‐dermal boundary occur until its disappearance and a thick layer of pre‐canoine is formed. This layer is progressively mineral‐zed; and finally an organic intermediate layer differentiates between the ganoine, which is a hyper‐nineralized tissue, and the overlying epidermis.This ultrastructural study demonstrates rather un‐quivocally the involvement of the inner epidermal layer (EL) in the appearance and growth of the ganoine. It suggested that these epidennal cells can be compared functionally to the inner dental epithelium (IDE) described during mammal tooth morphogenesis. Consequently, our results allow us to propose that ganoine an be identified as true enamel, although additional lata are necessary to analyze the proteinaceous com‐ponent of i

ISSN:0002-9106    

DOI:10.1002/aja.1001800409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe kidney of R. unicornis has almost 80 closely apposed lobes, all appearing peripherally. Every lobe, almost enclosed by a collagenous septum, resembles a deformed truncated cone. The pelvis proper is a small pouch which divides into a cephalic and a caudal urothelial‐lined fibromuscular conduit. The terminal collecting ducts of every lobe open into a tubus maximus. This is lined by cuboidal cells and otherwise has no wall. There is no papilla. All lobes finally empty through the 18 primary infundibular orifices at the pelvic conduits. A primary fibromuscular infundibulum typically yields a secondary one supplying an adjacent lobe. Two or three lobes can use a common tubus maximus by “convergence” of their medullae.Tubus maximus, terminal collecting ducts and deep outer medulla are embraced by a fibromuscular calyx which is the peripheral extension of an infundibulum and is fused to the outer medulla. There is thus no vault between medulla and calyx. Large intralobar veins are fused to the outer wall of the calyx. The possible significance of this is discussed.The cortex is the only part of a lobe which has contact with infundibulum, pelvic conduits, or pelvis proper.The kidney has about 16 million glomeruli which form 5.8% of the adult's cortical mass. Many adult mammals, from mouse to rhinoceros, fit into the log10‐log10slope relating number of glomeruli per kidney to body‐mass. Neonatal rhinos at term have mature glomeruli throughout the cortex. The small size of the glomeruli and the large number per field allow 16 million in an 118

ISSN:0002-9106    

DOI:10.1002/aja.1001800410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001800401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY