摘要:

AbstractFour major pancreatic hormones were immunolocalized at the light and electron microscopic levels in the pancreas of the Nile crocodile,Crocodilus niloticus.Immunogold was used for electron microscopy, and peroxidase‐antiperoxidase was used for light microscopy. Somatostatin‐positive D‐cells and pancreatic polypeptide‐containing F‐cells accounted for about 60% of the immunoreactive cells in the ventral pancreas. Glucagon‐positive A‐cells were the least frequent cell type in the ventral pancreas, about 15%, but were the predominant cell type, about 40%, in the pancreas that was dorsal in character. An expanded population of D‐cells (relative to mammals and other higher vertebrates) in association with two very different numbers of A‐cells can be expected to have important consequences for the homotropic control of secretory activity of the endocrine pancreas as well as for the function of the acinar pancreas. F‐cells were absent from the dorsal part of the pancreas, whereas insulin‐containing B‐cells were slightly more abundant in this portion of the pancreas. The regional character of the endocrine pancreas was related to the complex looping of the proximal small intestine.Without immunolabeling, only B‐granules were morphognomonic in electron micrographs. The insulin‐reactive B‐granules were the smallest (370 nm) of the secretory granules and were followed in size by somatostatin‐positive D‐granules (380 nm). The pancreatic polypeptide‐containing secretory granules were the largest (580 nm). Glucagon‐reactive A‐granules (430 nm) sometimes exhibited a protuberance or extension of secretory granule matrix and limiting membrane. Such a morphological feature has previously been associated with secretion of glucagon and the initiation of insulin secretion. Taken together these studies indicate that protuberances have a significant, but as yet undefi

ISSN:0002-9106    

DOI:10.1002/aja.1001780202

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe ultrastructural morphology of the cellular and extracellular components of the developing myocardial capillary wall—from the 16‐day‐gestation fetus of the rat to the 21‐day neonate—was examined. A morphometric analysis of plasmalemmal vesicles and of coated vesicles and pits of capillary endothelial cells was performed during the same developmental period. As the lateral extensions of the capillary endothelial cells change from irregular to regular in their thickness during development, there is an increase in the number of plasmalemmal vesicles and a progression from clusters of plasmalemmal vesicles to a uniform distribution in the endothelial cell. The ratio of vesicles which are open to the luminal front, which are “free” in the cytoplasm, or which are open to the abluminal front of the endothelial cell was consistent throughout development. The numerical density of plasmalemmal vesicles demonstrates a gradual and significant increase. In contrast, the numbers of coated vesicles and pits are variable within a very narrow range, and no pattern of increase or decrease is discernible during development. Similarly, there is no change in interendothelial cell junctions, which consist of occluding and primitive adhesive junctional types, during development. The lamina densa of the basal lamina gradually develops from discontinuous, patchy densities along the abluminal surface of the endothelial cells to a continuous and distinct layer by 21 days gestation. The presence of the proteoglycan species in the developing basal lamina was assessed with the cationic dye ruthenium red (RR), and the appearance of RR‐marked proteoglycans was found to parallel the appearance of lamina densa material. The RR sites appear discontinuously in patches; and later, the RR sites appear in a continuous and regular planar lattice in the lamina rara interna and externa at 21 days gestation. A complete array of RR‐stainable anionic sites outside a continuous lamina densa near birth indicates that the basal laminae of developing capillaries in the heart are morphologically, and in part biochemically, mature by the end of the first neonatal week.Our results show that the endothelial cells and the subtending basal lamina of myocardial capillaries gradually mature morphologically during the final days of gestation and the first neonatal week. The finding of tight junctions and small areas of vesicle concentration in fetal endothelial cells could indicate that sites of permeability are limited early in myocardial capillary development and that these vesicular sites increase as gestation proceeds and as the myocardial c

ISSN:0002-9106    

DOI:10.1002/aja.1001780203

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

年代:1987

数据来源: WILEY

摘要:

AbstractPossible changes in the epithelial cells of the pigeon choroid plexus induced by administration of thyroid powder (Thyradin), 2,4‐dinitrophenol, and cycloheximide were studied by scanning and transmission electron microscopy. A marked increase in the number of large bulbous and bleblike protrusions on the apical end of the epithelial cells was observed after oral administration of Thyradin for a month. The endoplasmic content of the protrusions consisted mainly of electron‐lucent material. These results provide morphological evidence for the stimulatory effect of Thyradin.Intramuscular injections of 2,4‐dinitrophenol for 15 days caused the collapse or deformation of the mitochondria and bleblike or bulbous protrusions. This indicates that changes in the surface configuration of the choroid plexus are controlled by an energy‐dependent mechanism. The decrease of protrusions and polyribosomes and increase of the tubular saccules of varying electron density, size, and shape were noted in cells after 15 days of intramuscular cycloheximide injection. The electron density of the protrusions is lower than that of the control pigeons.The results of this study suggest that a curious pleomorphic structure on the apical surface of the choroid epithelial cell of pigeon is closely related to the functional state of choroidal cells. The study also demonstrates that a secondary ultrastructural response due to diverse physiologic effects is reflected in the architecture of the choroid plexu

ISSN:0002-9106    

DOI:10.1002/aja.1001780204

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

年代:1987

数据来源: WILEY

摘要:

AbstractA remarkable projection of bleblike protrusions, the expulsion of organelles into the protrusions formed on the apical surface, and the separation into the ventricular lumen of these protrusions was the general cellular response of choroidal epithelial cells to intravenous injection of cytochalasin D (CD). The compact microfilament mass and agglomeration of microtubules at the base of the cluster of protrusions reflect the results of cell contraction and displacement of microfilaments induced by CD.In earlier stages after intravenous injections of colchicine, an obvious increase in the number of varioussized vesicles, vacuoles, and lysosomes in the Golgi region was detected. In the later stages, these organelles were seen to accumulate in the basal portion of the epithelial cells. These changes were accompanied by an increase in vacuoles and the disorganization and displacement of the Golgi complex, and they coincided with a decrease in the number of microtubules in apical and basal cytoplasm. These findings suggest that the action of colchicine results in destruction of the three‐dimensional architecture between cytoskeletal network and cell organelles.The present results suggest that the cytoskeletal network plays a role in the spatial coordination of the three‐dimensional architecture of cell organelles. The study also indicates that the structural differences in the ventricles of the choroid plexus in drug‐treated pigeons are manifestations of regional functional specialization in different parts of the ventricular s

ISSN:0002-9106    

DOI:10.1002/aja.1001780205

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

年代:1987

数据来源: WILEY

摘要:

AbstractTo describe lung growth qualitatively and quantitatively from prehatch to adulthood of an unselected line of turkey, a precocial a avian species, 36 male turkeys, three in each age group, were killed at 22 and 25 days of incubation, on hatch day, and at 1, 4, 7, 10, 14, 21, 28, 112, and 420 days of age. Body weight and lung volume were measured. A three‐level cascade sampling system was used to prepare lung tissue for morphologic and morphometric observation by light microscopy. Point and intersection counting were used to estimate volume and surface densities of lung compartments relative to lung volume. Absolute volumes and surfaces of lung compartments were calculated. Bilogarithmic regressions provided allometric equations to describe growth of the lung in three phases: (1) Tissue proliferation—explosive growth of lung volume relative to body weight and of the gas‐exchange compartment within the lung. At 22 days of incubation there were few air and blood capillaries and a great deal of tissue that looked like mesenchyme between the parabronchin. Within the 6 days prior to hatch, the surface area of air capillaries increased 11‐fold and of blood capillaries 27‐fold, whereas the volume of interparabronchial tissue decreased 58%. (2) Equilibrated growth—from hatch day to 28 days of age, most lung compartments grew evenly with lung volume. (3) Regulated growth—from 28 days of age to adult, all lung compartments, except large vessels and exchange compartment, grew more slowly than the entire lung. Interatrial septa lengthened and their epithelial covering thinned, infundibula became more apparent, and interparabronchial connective tissue reached a minimal volume density in t

ISSN:0002-9106    

DOI:10.1002/aja.1001780206

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

年代:1987

数据来源: WILEY

摘要:

AbstractComparisons of lung growth in two genetic lines of turkeys, one unselected and one selected for increased body mass, were used to evaluate the lung's alteration in structure with changes in body form or physiology. Seventy‐two male turkeys, 36 genetically selected for early rapid growth and large pectoral musculature, and 36 unselected birds, were killed at 12 different ages to compare lung growth in the two lines. Body weights and lung volumes were determined. A three‐level cascade sampling system was used to prepare lung tissue for qualitative and quantitative observation by light microscopy. Allometric equations describing growth of lung volume and lung compartments relative to body weight in two phases (tissue proliferation and equilibrated growth) were compared between lines of turkey for differences in slopes or intercepts. Means of data for 112‐ and 420‐day‐old birds were also compared.There were no qualitative histological differences observed between lungs of the two lines of turkey, yet there were morphometric differences in lung growth relative to body weight. During equilibrated lung growth, there was less rapid growth of air and blood capillary volumes and surfaces relative to body weight in the selected than in the unselected turkey. The gasexchange compartment did not enlarge concomitant with the large increase in muscle mass of the selected turkeys, while large‐vessel volume and small‐airway volume grew similarly to body weight in both turkey lines. We conclude that the lung of the selected line of turkeys did not show an enlarged gas‐exchange compartment relative to the greater body muscle mass, but it did show enlarged vessels and con

ISSN:0002-9106    

DOI:10.1002/aja.1001780207

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis study evaluates the ethanol toxicity for fetal development at different circadian stages. Pregnant mice were given a single intraperitoneal ethanol injection on day 7, 8, or 10 of gestation at one of four circadian stages (0700, 1300, 1900, or 0100 hr). The dams were killed on the day before term (day 18). Prenatal exposure to ethanol resulted in an increased number of resorptions, reduced fetal body weight, and produced an increased incidence of external alterations. The severity of damage was related to the dose, the period of gestation, and particularly to the circadian stage at the time of treatment. Ethanol had the greatest effect on the embryo of a mouse when administered at the mid‐dark span. Consequently exposure to a single dose of ethanol at one time or another along the 24‐hr time scale during organogenesis has important implications for the substantially increased r

ISSN:0002-9106    

DOI:10.1002/aja.1001780208

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.

ISSN:0002-9106    

DOI:10.1002/aja.1001780209

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe mandibular condyles of eight growing male monkeys (Macaca fascicularis) were analyzed by using a combination of radioautographic and morphometric techniques. This was done with the aim of examining the dynamics in the structure and growth activities of the articular tissue covering as well as of the subchondral zone of erosion. The animals received 1 mCi/kg body weight3H‐proline 24 hr and 0.5 mCi/kg body weight3H‐thymidine 3 hr prior to death. Their age was estimated on the basis of skeletal maturation as recorded from radiographs of the hand and wrist. Consistently, (1) the proliferative activity in the intermediate layer, (2) the rates of cell turnover and growth of chondroblasts and chondrocytes, (3) the rates of extracellular matrix production in the intermediate and chondral layers, as well as (4) the resorptive and (5) appositional activities in the zone of erosion were characterized by an in‐concert behavior. This behavior suggests a general synergistic control of the various cell dynamic and metabolic processes affecting the rate of normal condylar g

ISSN:0002-9106    

DOI:10.1002/aja.1001780210

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe ultrastructural surface features of the normal fourth ventricular floor of seven human embryos ranging from Carnegie stage 14 to stage 19 (crown‐rump length: 7.6–16.2 mm) were examined by using scanning electron microscopy (SEM). Low‐power SEM views showed the median sulcus, sulcus limitans, and neuromeres, transient structures characteristic of the earlier embryonic period. High‐power SEM observation revealed supraependymal cells (SE cells) and supraependymal fibers (SE fibers) which exhibited a characterisitc localization, as well as generalized surface‐membrane modifications such as microvilli and cilia. SE cells could be classified into two major groups. The type 1 SE cells seem to possess neuronal functions, as deduced from morphological similarities to their counterparts in adults and the specialized distribution closely related to neuromeres. The type 2 SE cell morphologically resembled the phagocytic SE cell described in related literature. SE fibers ran a course either rostrocaudally in the median sulcus or mediolaterally on the neuromeres, most frequently near the interneuromeric cleft; they made contact with type 1 SE cells and ependymal surface modifications and then penetrated the ependy

ISSN:0002-9106    

DOI:10.1002/aja.1001780211

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

年代:1987

数据来源: WILEY