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  • 1
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The renal corpuscle of the opisthonephric kidney of the Great Lakes lamprey, Petromyzon marinus L., is described. In the larvae (ammocoetes) several renal corpuscles, each consisting of lobed glomeruli and Bowman's capsules, are placed behind one another and there is a progressive lengthening of the posterior corpuscles as the animal ages, apparently by the addition of new glomeruli posteriorly. Bowman's capsule surrounds a single loop and consists of parietal and visceral layers which are similar to those seen in higher vertebrates.The kidney of the adult has a single complex renal corpuscle which extends almost its entire length. Present evidence indicates that the adult kidney is formed during transformation and that the larval renal corpuscles do not contribute to the single elongate corpuscle of the adult. A large number of lobed glomeruli, lying one behind the other, form the elongate glomus. Interposed between each pair of lobes is the dilated end of a nephron. There are no typical Bowman's capsules in the adult although where these nephric capsules invest the blood vessels of a lobe they develop podocytes similar to those of the visceral layer of Bowman's capsule and elsewhere they consist of a simple squamous epithelium similar to that of the parietal layer.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Morphogenesis of the retina of the Sprague-Dawley albino rat was studied by light microscopy from day 11 of gestation until 225 days after birth. A quantitative analysis during development of retinal volume, thickness of the entire neural retina and thickness of each of the retinal layers, both posteriorly and peripherally, was made. The results indicate that initially a single neuroblastic layer forms and continually thickens by mitosis at its outer border. The retinal layers then form in sequence, moving from the inner retinal border outward and always beginning posteriorly and then spreading peripherally. The transient layer of Chievitz does not appear. All adult layers are present by eight days after birth and each layer thins after reaching its maximal thickness. Total thickness of the retina excluding pigmented epithelium, is greatest on postnatal day 5, but retinal volume only reaches a peak on postnatal days 7 to 12. The nerve fiber, inner plexiform, outer plexiform and bacillary layers all continue to increase in thickness after the ganglion cell and inner and outer nuclear layers reach their maximal width and are beginning to become thinner.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 127 (1970), S. 357-367 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study deals with the postnatal growth and remodeling changes that take place in the cranial bone of Macaca mulatta. Multiple ground sections were prepared throughout each component bone from the calvaria and cranial floor of young, rapidly growing specimens having primary or mixed dentition. These sections were then analyzed for (1) the different types of inward-growing and outward-growing bone tissues present, and (2) the distribution of resorptive and depository periosteal and endosteal surfaces. Using this information, the remodeling history of each bone was reconstructed and the overall growth pattern of the craninum as a whole was determined. The growth changes that characterize the brain case of the monkey were then compared and contrasted with those in Homo. While a number of distinct similarities were observed in their respective growth and remodeling processes, several marked differences were also found. These occurred largely in certain parts of the cranial floor and they appeared to be associated with corresponding differences in the size, configuration, and disposition of the brain in the two species and also with factors related to body posture and facial prognathism.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The structure of the guinea pig visceral yolk sac from 26 days of gestation to term was studied by transmission and scanning electron microscopy. Particular emphasis was placed on the columnar endoderm cells of the villous portion of the yolk sac. The apical cytoplasm of the endoderm cells contained numerous membrane invaginations, endocytic vesicles, dense tubules and large vacuoles which appeared to form an interrelated absorptive system. The saccular invaginations of the apical cell membrane were specialized by the development of both an amorphous extracellular coat and an internal coat. Both the endocytic vesicles and dense tubules were thought to be derived from the saccular invaginations following detachment of the latter from the cell surface  -  the endocytic vesicles forming by fusion of saccules creating progressively larger structures, and the dense apical tubules forming by a process involving fluid loss from the saccules. Large vacuoles were present deeper in the apical cytoplasm; these probably were formed by fusion of smaller vesicles. The supranuclear cytoplasm contained numerous dense droplets and a Golgi zone. The possible relationships of the droplets to the vacuoles was discussed.
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  • 5
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Tissues from adult Sprague-Dawley rats fixed by perfusion with buffered aldehydes for a combined study of the vascular system of the brain are described in light and electron microscopy. In these preparations lack of shrinkage prevents the formation of perineuronal and perivascular spaces. However, connective tissue stains indicate restricted tissue space along the course of small arteries and veins. In fine structure this space is found within the walls of the vessels. It consists of a tubular extension of tissue space bounded inwardly by the endothelial boundary (basement) membrane and outwardly by the neural boundary membrane. Between these boundaries the formed elements of the media and the adventitia are found. The media consists of a thin layer of smooth muscle cells; each cells being enclosed in its own boundary membrane. The adventitia consists of cells and fibrous elements of the connective tissues which are derived, near the surface of the brain, from the intermingling of pial and vascular leptomeninges. This “neural” portion of the tissue space extends from the depths of the capillary bed (where it is obliterated by the fusion of boundary membranes), along the course of the blood vessels, through the subarachnoid space and into the general tissue space of the body.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 127 (1970), S. 423-435 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The avian kidney is composed of cortical and medullary lobules, with the former surrounding branches of the renal vein. Cortical lobule diameters varied intraspecifically according to level of association with the venous system, and interspecifically were greatest in nonpasserines. All cortical tissue examined contained maculae densae.Each medullary lobule receives collecting ducts and loops of Henle from several cortical lobules. Such a complex may be viewed as a lobe, and the entire kidney as multilobar. The relative diameter of a medullary lobule appears directly related to the number of cortical units with which it is associated. Distally, most lobules vary from 0.3 to 0.5 mm in diameter, and contain 20 to 30 collecting ducts. The latter fuse dendritically as they traverse a medullary unit, and eventually form ureteral branches which drain directly into the ureter.Intramedullary organization in passerines involves aggregated thin limbs bounded by collecting ducts which in turn are surrounded by uneven layers of thick limbs. While some nonpasserines approach this pattern, others lack apparent organization of intramedullary elements. The turn of Henle's loop was restricted to the thick limb in all birds examined. Avian and mammalian thick limbs are similar in diameter, but avian thin limbs are typically wider.Small kidneys have short ureteral branches with primary stems clustered in each kidney division. In larger kidneys, where medullary lobules are often remote from the ureter, ureteral branches are long and not clustered.
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  • 8
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Regeneration of the gastrocnemius muscle from minced transplanted muscle fragments was studied in 46 rats. The jumping complex of muscles (gastrocnemius, soleus and plantaris) was removed from the donor and minced into 1 mm3 fragments. In one experimental series minced muscle was orthotopically implanted into sibling animals, and in the other series minced muscle was implanted into non-sibling animals of the same strain. During the first week after implantation, regenerative activity in the homotransplanted muscle fragments was intense and did not differ histologically from that occurring in autotransplanted muscle. Staritng in the second week, areas of regenerating homotransplanted muscle fibers became infiltrated with small lymphocytes. Despite relatively massive cellular rejection in the regenerates, individual skeletal muscle fibers regenerated to maturity. Regenerates from homotransplanted muscles often attained the same gross from as regenerates from auto-transplanted material, but in no case was the amount of muscle fibers in homografted regenerates greater than 50% of that seen in regenerates arising from autografted muscle fragments. About half of the advanced regenerates were reduced to broad bands of connective tissue containing no muscle fibers.
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  • 9
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chick embryos of graded ages, ranging from freshly laid eggs to one week incubation, were prepared for electron microscopy.Interstitial bodies are expressions of “ground substance” that resemble structureless masses of cytoplasm without enclosing plasmalemma. They measure from 0.1 to ca. 1 μ in diameter. Toward the end of the first day of incubation they are found in the tissue space near to or in contact with the ectodermal boundary (basement) membrane. They seem to contribute to its increasing amorphous component. Microfibrils first appear close to or in contact with the ectodermal boundary membrane and are similarly related to interstitial bodies. At 44 hours interstitial bodies are especially numerous where the neural tube is separating from the ectoderm. Here boundary membranes have become intermittent and interstitial bodies appear to contribute to their repair. By the fourth day interstitial bodies are less numerous. Many appear to break up. Their edges tend to become dispersed into clouds of finely granular material, especially in areas of the tissue space occupied by wisps of microfibrils. The close association of amorphous ground substance and extracellular fibrils persists indefinitely.
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  • 10
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The choroid plexus was studied in 217 necropsy specimens from human beings two months to 94 years of age. With advancing age, the height of the cuboidal epithelial cell gradually decreases, many becoming squamous. Cytoplasmic vacuoles increase in number. Focal stratification is not an artefact, and is evidence of proliferation. The proliferated cells eventually desquamate, becoming round, large and foamy as they accumulate intracytoplasmic lipid and degenerate. The findings indicate that cellular desquamation occurs during life. Filaments of mucopolysac-charides are common in the choroid plexus of old people. Stromal alterations associated with increased age consist of a gradual increase in the amount of connective tissue, in number of meningocytes and psammoma bodies, and in severity of hyalinization, fibrosis, fragmentation of connective tissue fibers and calcification. Most psammoma bodies are found in the glomus choroideum. Non-lamellar calcific foci occur mainly in the matrix of the choroidal villi and fronds. Formation of psammoma bodies is associated closely with the meningocytic whorls. Lipids, mucopolysaccharides and mucins are identified in both epithelial and stromal components of the choroid plexus. Lipids appear in the stroma later in life. It is suggested that lipid in the cytoplasm of desquamated choroidal eipthelial cells is one source of lipids in the cerebrospinal fluid.
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