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  • 1
    Electronic Resource
    Electronic Resource
    Pleuroperitoneal canal closure in the rat (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 208 (1984), S. 445-460 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Pleuroperitoneal canal development and closure were studied with light microscopy and transmission and scanning electron microscopy in 12.75- to 16-day fetuses. The major chronological events described in this paper are (1) the caudal tips of the lung buds projecting to the pleuroperitoneal canal (12.75 through 13.50 days); (2) the caudal tips of the lungs becoming situated medial to the canal areas at 14 days; and (3) both canals becoming crescent shaped with a uniform diameter until closure. Concurrently, the developing diaphragm and associated pleuroperitoneal folds assume more caudal positions. Both canal regions are bordered by the liver, lung, gonadal ridge, and suprarenal glands. In addition, on the left side, the stomach and mesogastrium also border the early canal. The right canal closes before the left (right, 14.75-15 days; left, 15-15.25 days).The results suggest that the pleuroperitoneal folds are pushed together, thereby closing the canals. This may be accomplished by one or a combination of the following: (1) enlargement of the liver pushing the ventral fold dorsad and a molding of the liver to the dorsal body wall caudal to the canal; (2) liver and thorax enlargement which appears to pull the dorsal fold taut against the central fold; and (3) a change in the orientation of the canal near the time of closure. Each canal is fully closed by the mergence of the dorsal and ventral fold mesothelia and mesenchyme. This study provides a basis for relating pleuroperitoneal canal development and closure to the surrounding organs and tissues.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092080315
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  • 2
    Electronic Resource
    Electronic Resource
    Morphogenesis of chordae tendineae. I: Scanning electron microscopy (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 210 (1984), S. 629-638 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The formation of the chordae tendineae of the left atrioventricular valve in the chick embryo is described using scanning electron microscopy. These supportive structures for the valve cusps develop between days 6 and 13 of incubation. Elevations which represent the primitive papillary muscles form on the ventricular wall. These elevations bifurcate into thin, weblike folds which are attached to the primitive valve cusps. The folds are the primordia of the chordae tendineae. Linear ridges develop on the web between the cusp and papillary muscle. These ridges alternate with depressions. The depressions become perforate to create the individual chorda from the linear ridges. Multiple perforations form initially but they typically consolidate to create one large aperture between two chordae. Some interchordal connections of tissue do persist throughout the period studied. During the period of perforation, prominent rounded cells are typical of the endocardium between the chordae. These cells are similar at the scanning electron microscope level to those present in the formation of the foramina secunda of the atrial septum. Primary, secondary, and tertiary chordae tendineae appear to develop in the same manner. First order chordae (those attached at the free margin of a cusp) are not found in the chick embryo. The majority of the chordae are second order, which insert into the ventricular surface of the cusp a short distance from the free edge. These chordae typically have a horizontal banding or grooving along their length. Third order chordae which extend from the papillary muscle to the ventricular wall are also present. It is suggested that chordal development is a programmed cellular and hemodynamic event.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092100410
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  • 3
    Electronic Resource
    Electronic Resource
    Pigmented cells in the leptomeninges of the cat (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 210 (1984), S. 125-132 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cells laden with pigment granules are described in the leptomeningeal tissues of the cat and kitten. These cells can be identified consistently by gross observation following vascular perfusion. The fusiform or stellate pigmented cells are most often found in association with the outermost layers of the arteries of the subarachnoid space. They are typically separated from the cerebrospinal fluid by an attenuated layer of pial cells. Vessels that are described as having pigmented cells along their course are the anterior and posterior cerebellar; the anterior, middle, and posterior cerebral; and the basilar. Electron microscopic studies confirm the presence of abundant pigment granules. The pigment granules are the predominant component of the cytoplasm. Few organelles are demonstrable except for a large central nucleus. The data provide suppport for the concept of neural crest contribution to leptomeningeal structures. Identification of this isolated, easily defined population of melanocytes may provide a model for further studies of neural crest distribution as well as experimental approaches to melanogenesis and melanoma production and control.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092100115
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  • 4
    Electronic Resource
    Electronic Resource
    The fine structure of subarachnoid macrophages in the ratThis study was supported by grant NS 09363, United States Public Health Service. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 174 (1972), S. 469-475 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Macrophages associated with the subarachnoid space have fine structural characteristics which distinguish them from macrophages found elsewhere. The specific location of a macrophage in this area influences its morphology. Macrophages found in the subarachnoid space characteristically have a highly vacuolated cytoplasm. When cells of the pia mater separate the macro-phage from the subarachnoid space, the extreme vacuolization is not present and a more compact cytoplasm prevails. Frequently macrophages found in the median longitudinal fissure contain compound reticulated inclusions. Extracellular bodies resembling compound reticulated inclusions have been observed.The presence of lobulated nuclei, lysosome-like inclusions, phagosomes, and other characteristics of these cells is reported. The possible origin and function of subarachnoid space macrophages is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091740406
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  • 5
    Electronic Resource
    Electronic Resource
    High-voltage electron microscopy of extracellular fibrillogenesis (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 150 (1977), S. 1-33 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: High-voltage electron microscopy was employed to observe developing extracellular connective tissue elements in the cervical perinotochordal and perivertebral regions in the chick embryo from 2 through 15 days' incubation. During days 2 and 3, small (10 nm) and large (18-20 nm) microfibrils surrounded the notochord, becoming evident around fibroblast-like cells in day 4. Amorphous material, globular granules and microfibrillar bundles were present at this time. Microfibrillar length increased as did the total population of microfibrils. At four days microfibrils 3-5 nm in diameter arose in all directions from globular granules. During day 9 and thereafter to day 15, microfibrillar diameters increased. This growth formed unit collagenous fibrils 30 nm in diameter or greater. Axial periodicity became evident at day 14.Small microfibrils appear to be composed largely of glycoproteins and do not contain a significant amount of collagen. The globular granules and associated filaments are probably proteoglycans. The amorphous material is believed to provide molecular collagen to developing fibrils. Large microfibrils and unit collagenous fibrils contain significant amounts of molecular collagen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001500102
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  • 6
    Electronic Resource
    Electronic Resource
    The fine structure of developing unit collagenous fibrils in the chickAided by a grant from the North Dakota Heart Association. NIH grants NS 09363 and Institutional grant FR-05407 for General Research Support contributed significantly to laboratory expenses. (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 140 (1974), S. 237-261 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Perivertebral cervical connective tissue was taken from chick embryos of incubation ages from 72 hours through hatching and from 4, 8, 12, and 16 week old chicks. Preparations for electron microscopy were routine except for en bloc staining with 5% aqueous uranyl acetate. Collagenase digestions of thin sections confirmed the presence of tropocollagen in banded extracellular fibrils.Banding becomes demonstrable in fibrils at about seven days but repeating units cannot be measured. Close to connective tissue cells the banded material is present in wide sheets. Partially banded fibrils (250 Å wide) physically related to microfibrils are present in acellular regions. Growth in fibril diameter is slow through the second week (up to 300 Å) but increases nearly 200 Å on days 14 and 15. Fibrils larger than 500 Å resist uranium and lead staining following the period of accelerated growth. Smaller fibrils (〈 500 Å) continue to stain well. A basic banding pattern of measurable periodicity is established by the eighth day. This consists of a major doublet, two minor doublets, and two singlets. The intraperiod distance does not change significantly with growth (510 Å average). Additional bands near the first minor doublet and singlets of the basic pattern are first clearly demonstrable at 14 and 15 days. Ambiguities in banding and period length are believed to be due to plane of section, interference with detail by other fibrils and flaky amorphous material or possibly to differential shrinkage along the length of a single fibril.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001400209
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  • 7
    Electronic Resource
    Electronic Resource
    The fine structure of the pia mater of the ratThis study was supported by grant NS 09363, United States Public Health Service. (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 133 (1972), S. 349-367 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Tissue from the central nervous system of 11 adult Sprague-Dawley rats fixed by vascular perfusion with buffered aldehydes was used in a study of the fine structure of the pia mater. Surface tissue from the cerebral and cerebellar cortices, ventral pons, olfactory bulb, tuber cinereum, spinal cord, superior colliculus, optic chiasm, and median longitudinal fissure was examined. Variations in pial composition occurred within each of these selected areas although a basic pattern prevailed throughout.The components of the pia mater are described under three categories: pial cells, extracellular elements, and macrophages. The pial cells are the more numerous cell type, possessing long, flattened cytoplasmic processes which contain few inclusions. These cells vary in thickness in any one area and there may be from one to six distinct cytoplasmic layers. Fenestrations between pial cell processes or total absence of pial cells are occasionally encountered. Unit collagen fibrils make up most of the extracellular material of the pia. These have a major period of about 550 Å and are about 400 Å wide. Macrophages are rounded up and contain various cytoplasmic inclusions. In normal animals evidence of active phagocytosis is rare.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001330309
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