摘要:

AbstractMorphometric measurements of bone marrow sinus wall adventitial and endothelial cells were made in normal and leukemic samples by using a Bioquant II computer image analysis program (R&M Biometrics, Nashville TN). Electron micrographs of bone marrow from at least eight mice per group were studied in normal and day‐2, day‐4, and day‐6 leukemic postinoculation groups. The adventitial cells abuting the sinus endothelium was found to be significantly reduced with disease progression. In addition, adventitial cell area and perimeter were found to be drastically reduced with disease progression whereas endothelial cell area and perimeter showed no significant differences. Other investigators have suggested that the marrow sinus adventitial cell cover is drastically reduced in rodent leukemias (Chen et al.;Blood, 39:99–112, 1972; Campbell;Am. J. Anat., 142:319–334, 1975). Our findings give quantitative data to support this h

ISSN:0003-276X    

DOI:10.1002/ar.1092240302

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo determine the architecture of the atrioventricular (AV) junctional region, structures in atrial preparations were correlated to those in serial sections made either parallel or perpendicular to the long axis of the AV node (AVN)/AV bundle complex. The results demonstrated the following for the first time: (1) A right medial atrial wall (MAW) extends anteriorly from the interatrial septum, superior to the interventricular septum (IVS). (2) An atrial interventricular septum (A‐IVS) groove is located between the base of the MAW and the crest of the IVS. (3) Three atrionodal bundles converge to form a proximal AV bundle (PAVB), which in turn is contiguous with the AVN. The atrionodal bundles are associated with the MAW or the superomedial and inferolateral margins of the coronory sinus. Terminal portions of the atrionodal bundles and the PAVB reside within the A‐IVS groove. The AV bundle was termed distal (DAVB) to avoid confusion. (4) The location of the AVN/DAVB complex topographically is deep to the apex of the septal cusp of the tricuspid valve subjacent to the MAW. Intracardially, the AVN/DAVB complex is within the central fibrous body. Significantly, this study resulted in the first unequivocal demonstration of discrete bundles of myocardial fibers associated with the atrial end of the AV node. Moreover, it appears likely that the atrionodal AV bundles are continuous with the sinoatrial nodal extensions, thereby forming internodal tra

ISSN:0003-276X    

DOI:10.1002/ar.1092240303

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe cerebral cortices are nourished by blood circulating through a capillary network branching from parent arteries. In this paper, vasculogenesis of the cerebral cortices in developing rats (11–18 days after birth) was studied by light and electron microscopy after intravenous administration of horseradish peroxidase (HRP).In the first phase of vasculogenesis, tentacles grew out from the distal end of the vascular cord (tip cells), and in the second phase, they extended to the afferent blood vessel. The reaction product of HRP was distributed not only in the primitive vascular lumen, but also in the peripheral extravascular space of the vascular cord. Most tentacles were free from reaction product, but, in some cases where reaction product was detected, the intercellular spaces had spread into the tip cells and reached the root of the tentacles.After the tentacles contacted the afferent vascular cord, the two vascular cords approached and fused with each other. Blood serum was able to circulate between the two vascular cords via the irregular interstices formed among the endothelial cells, cytoplasmic processes, and tentacles. Later, the primitive vascular lumen developed to a sufficient size to allow for the circulation of blood cells. The sequential events in the process of fusion between two vascular cords are illustrated.The following two points were also noticed in this study: (1) during cerebral vasculogenesis, degeneration and vacuolization in primitive endothelial cells occurred only in some of the serial sections and did not play a significant role in the formation of vascular lumen, and (2) cerebral pericytal macrophages (CPM) (classified as fluorescent granular perithelial cells by the authors) appeared close to the vascular cord, although the biological meaning of it remained unknown in the present investigatio

ISSN:0003-276X    

DOI:10.1002/ar.1092240304

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

年代:1989

数据来源: WILEY

摘要:

AbstractAn immunohistochemical study of cardiac alpha and beta myosin heavy chain (MHC) expression during rat heart morphogenesis was performed. In tubular hearts (embryonic days, ED10–11) coexpression of both cardiac alpha and beta MHC was found throughout the heart, except for the left free wall of the atrium, where only cardiac alpha MHC is detected. A transition of coexpression to single expression of either cardiac alpha or beta MHC begins at the same time in both atria and ventricles but requires a longer time for completion in the ventricules; in the atria transition takes place during the period ED 12–13 and in the ventricles during ED12–15. Furthermore, expression of cardiac alpha and beta MHC was detected in the sinus venosus, and cardiac alpha MHC expression was detected in the pulmonary veins.A comparison of the results obtained in chicken embryos revealed that in tubular hearts the expression pattern is similar, whereas in later developmental stages two major differences were observed: (1) transition of coexpression to single expression in rat ventricles appears to take a longer developmental period; (2) the persistence of areas of coexpression in the sinoatrial junction, dorsal mesocardium, atrioventricular junction, and outflow tract, as found in the chicken embryo in later developmental stages, is not found in the rat

ISSN:0003-276X    

DOI:10.1002/ar.1092240305

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

年代:1989

数据来源: WILEY

摘要:

AbstractPolyclonal and monoclonal antibodies recognizing different species of keratin molecules were used to characterize the expression of keratins by epithelial cells in the murine thymus. Some of the reagent antibodies used in this study were raised against human keratins and cross‐react with murine keratins. Both cortical and medullary thymic epithelial cells were found to contain keratin with apparent molecular weight of 52 KD, which is considered to be associated with simple or stratified epithelium. In addition, medullary epithelial cells were found to contain other species of keratin molecules, ranging in apparent molecular weight from 40 to 67 KD. This latter population of keratins is thought to be associated with stratified and/or keratinizing epitheli

ISSN:0003-276X    

DOI:10.1002/ar.1092240306

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

年代:1989

数据来源: WILEY

摘要:

AbstractOsteoclast‐like multinucleated cells were formed from mouse bone marrow mononuclear cells, and their morphology on coverslips and on calcified dentine slices was compared by means of transmission electron microscopy. Addition of 1α,25‐dihydroxyvitamin D3[1α,25(OH)2D3] to bone marrow cells cultured on coverslips greatly stimulated the formation of multinucleated cells within 8 days. These multinucleated cells had the cytological features of osteoclasts (abundant pleomorphic mitochondria, a large number of vacuoles and lysosomes, many stacks of Golgi membranes, and an extensive canalicular system), but they developed neither ruffled borders nor clear zones. The multinucleated cells appeared to result from direct fusion of mononuclear progenitor cells, whose structural features were similar to those of multinucleated cells. Like isolated osteoclasts, both multinucleated cells and their precursors exhibited an intense reaction for tartrate‐resistant acid phosphatase (TRACP) in the cisterns of endoplasmic reticulum and lysosomes. Multinucleated cells formed from alveolar macrophages in the presence of 1α,25(OH)2D3were totally negative for TRACP reaction. When marrow cells were cultured on dentine slices in the presence of 1α,25(OH)2D3, some of the multinucleated cells were located in the shallow resorption lacunae of dentine surfaces, and they developed the characteristic ruffled borders and clear zones. The narrow extracellular spaces of the ruffled borders, the adjacent pale endocytotic vacuoles, and the dark lysosomes located in the perinuclear cytoplasm of the multinucleated cells contained numerous apatite crystals delete in resorption lacunae. These results indicate that (1) the multinucleated cells formed on coverslips from mouse marrow cells treated with 1α,25(OH)2D3exhibit non‐functional basic features of osteoclast morphology, and (2) differentiation of the multinucleated cells into functional osteoclasts requires some components of calci

ISSN:0003-276X    

DOI:10.1002/ar.1092240307

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

年代:1989

数据来源: WILEY

摘要:

AbstractA methodology for three‐dimensional reconstruction from serial sections and interactive computer graphics is described briefly. This methodology was applied to study the morphogenesis of the cardiac myofiber pattern in the fetal and neonatal mouse heart (ventricles). Few organized in‐plane myofibers were found in the myocardial wall before 12 days postconception, but many fibers were observed in the very numerous trabeculae at all times up to birth. However, beginning at about 12 days, the number of fibers in the myocardial wall increases rapidly: these are seen predominantly in the transverse plane. The neonatal mouse heart, especially the left ventricle, resembles a small adult muscular artery. But the global myofiber pattern in the mouse heart at these stages appears to be more complex than might be inferred from earlier studies of the local myofiber pattern at a few sites in the ventricles of a few species of adult mammals. In particular, the pattern in and adjacent to the interventricular septum appears quite comp

ISSN:0003-276X    

DOI:10.1002/ar.1092240308

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

年代:1989

数据来源: WILEY

摘要:

AbstractTo investigate the biomechanical effects of juvenile growth changes in the rabbit masticatory apparatus a comparison was made of mastication in just‐weaned and adult animals. Mandibular movements in two planes were registered by cineradiography. Masticatory muscle activity was recorded by finewire electromyography. The same pattern of unilateral mastication was present in the two ages. The most important changes in the jaw movements are (1) a decrease of jaw opening speed and chewing frequency and an increase in jaw opening time, (2) a decrease in maximum gape in soft food and an unaltered gape in small‐particle hard food, and (3) an increase in lateral jaw excursion, mainly due to a more pronounced movement of the jaw to the balancing side (lingual phase). The contraction patterns were basically similar in the two ages. The higher chewing frequency in young animals was attained by a larger degree of overlap between opening and closing muscle activities. Young animals used relatively more EMG activity to chew hay, the hardest food. The changes in opening speed, gape, and chewing frequency are consistent with earlier predictions from the morphological changes, and so is the extra activity needed to chew hard food. The increase in lateral excursion was not predicted. It is suggested to be caused by cheek teeth wear, making possible smooth occlusal guidance of the jaw at the balancing side. Some of the changes in juvenile morphology can be viewed as adaptations to a changing d

ISSN:0003-276X    

DOI:10.1002/ar.1092240309

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

年代:1989

数据来源: WILEY

摘要:

AbstractLight microscopic immunolabeling studies were designed to identify and locate structural components within the cell‐free extracellular matrix which lies between the embryonic endocardial and myocardial tubes. Affinity‐purified antibodies were used to examine stage 15‐22 embryonic chicken hearts. Specimens were immunolabeled by using three different methodologies: (1) postembedding labeling of 10 μm cryostat sections, (2) preembedding labeling (en bloc) of whole hearts, and (3) postembedding labeling of ethanol/acetic acid‐fixed paraffin sections. Our results establish the spatial distribution of collagen type I and demonstrate for the first time the presence of collagen type IV and laminin in the myocardial‐basement‐membrane/c

ISSN:0003-276X    

DOI:10.1002/ar.1092240310

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen. An additional three animals were used to analyze the morphology, distribution, and histochemical profiles of the muscle fibers in the SB and TB subregions. Fibers were characterized on the basis of their reactions for myofibrillar adenosine triphosphates (alkaline and acid preincubation) and reduced nicotinamide adenine dinucleotide diaphorase (NADH‐D). The SB is primarily innervated by the rostral nerve branch and the TB by the caudal nerve branch. For two‐thirds of the muscle's length, the SB is separated from the TB by an aponeurosis, the membrana intermuscularis (MI). SB and TB fibers located posteroventral to the caudal margin of the MI are innervated variously by both nerves. Two populations of fibers were recognized, distinguishable primarily by (1) fiber diameter and (2) density of the NADH‐D reaction product. Compared to the TB, the SB possesses a higher average percentage of large fibers. Within the SB but not the TB the percentage of large fibers increases from deep to superficial. These data support our previous findings that the pars thoracicus of the pigeon is partitioned into at least two functional subunits, each with a potential for independent action on the wing during f

ISSN:0003-276X    

DOI:10.1002/ar.1092240311

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

年代:1989

数据来源: WILEY