摘要:

AbstractRat inferior colliculi were fixed by intracardiac perfusion of 4% methanol‐free formalin in an isotonic phosphate‐sucrose buffer, dehydrated in ethanol and studied during the first two weeks of postnatal life. The extracellular space during the first week was made up of intercellular gaps about 100–150 Å wide and large intercellular lakes (1–3 μ long) which diminished in size and number as maturation proceeded. Similar intercellular lakes were found in tissue fixed by immersion in glutaraldehyde containing ruthenium red. In these tissues an intense ruthenium red reaction product, distributed extracellularly, suggested an intercellular substance comparable to that described in adult brain. Intercellular lakes were also found in tissue dehydrated in acetone. Morphometric estimations indicated the extracellular space of neuropil during the first week to be about twice that of the adult, which was approached prog

ISSN:0002-9106    

DOI:10.1002/aja.1001240402

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

年代:1969

数据来源: WILEY

摘要:

AbstractForty pairs of humeri, from a series of embryos and fetuses ranging from 26 to 342 mm in crown‐rump length, were measured, radiographed, and sectioned for microscopic study.A primary bony collar was present before the end of the embryonic period, and in a 27 mm embryo it extended for nearly one‐third of the length of the humerus. Erosion of the collar occurred at the end of the embryonic period. By about 37 mm, endochondral ossification began, and cartilage canals were invading the proximal epiphysis.As endochondral ossification proceeded proximally and distally and growth zones became established, periosteal bone formation also proceeded longitudinally and, until about 18 weeks, extended about one millimeter beyond the zone of cartilage destruction in the growth zones. Subsequently the extents of periosteal and endochondral ossification were the same and at term occupied 79% of the length of the humerus.Trabeculation of the bony collar began in the embryonic period. Fusion of endochondral trabeculae with the inner aspect of the periosteal shell began by 61 mm. A central marrow cavity free of trabeculae was consistently present after 86 mm. Evidence of reconstruction appeared in the proximal end by 73 mm and in the distal end by 113 mm, and was always present after 97 and 125 mm respectiv

ISSN:0002-9106    

DOI:10.1002/aja.1001240403

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

年代:1969

数据来源: WILEY

摘要:

AbstractDuring limb regeneration of the newtTriturus, muscle first dedifferentiates giving rise to mesenchymal cells which, subsequently, differentiate to reform normal muscle. In dedifferentiating muscle, myofibrils and elements of the sarcoplasmic reticulum decrease gradually in number. Myofilaments become less distinct and seem to be supplanted by zones of amorphous material. Large masses of glycogen accumulate in dedifferentiating cells and mitochondria show a transient enlargement. In the later stages of dedifferentiation, glycogen decreases in amount while cytoplasmic ribosomes and cisternae of rough‐surfaced endoplasmic reticulum appear. Mesenchymal cells are formed by disappearance of all traces of myofilaments, by further elaboration of rough endoplasmic reticulum, and increase in number of Golgi complexes.During the earliest stages of differentiation, muscle has less endoplasmic reticulum and many more free ribosomes which occur in clusters or linear chains. Thin (−70 A) and thick (−135 A) filaments appear in the cytoplasm, often in association with ribosomal olusters, and shortly thereafter aggregate into small fibrils. In early fibrils, the thin filaments overlap the thick to produce I and A bands and the free ends of the thin filaments converge and cross to mark the site of the Z line. Fibrils enlarge by addition of filaments along their sides and at their ends. In larger fibrils, the H band and M line are apparent. Initially, the transverse tubular system develops by the confluence of vesicular inpocketings of the surface plasma membrane. The smooth sarcoplasmic reticulum is continuous with rough‐surfaced membranous cisternae. Some of the smooth tubules, probably sarcoplasmic reticulum, contain intracisternal masses of dense granular material and are situated adjacent to the Z line. When dense material occurs in the membranous structures, material of similar density and texture appears within the adjacent Z line. Normal muscle fibers are formed by fusion of myoblasts, increase in number and size of myofibrils, organization of transverse tubules and sarcoplasmic reticulum into triads, loss of ribosomes, and appearance of g

ISSN:0002-9106    

DOI:10.1002/aja.1001240404

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

年代:1969

数据来源: WILEY

摘要:

AbstractNine edible oils or fats (hydrogenated coconut, cod liver, Wesson, linseed, olive, butter, lard, corn and cocoa‐butter) were fed for 50–90 days to study the relation of saturation, chain length and essential fatty acid content to production of cardiovascular lesions. The specific oil or fat (selected for ranges in the above variables) was used as the dietary lipid in a high‐fat (28%), low‐protein (8%), hypolipotropic diet. Half of the animals received identical diets containing choline chloride (2 gm/100 gm of diet) as a lipotropic supplement.Atrial mural thrombosis and ventricular myocardial necrosis and calcification developed in all dietary groups. Atrial thrombosis was the most frequent lesion. The greatest incidence of atrial thrombosis occurred in mice fed the choline‐deficient, butter‐containing diet (92%) and the lowest incidence with the supplemented cod liver oil diet (20%). The diet containing unsupplemented hydrogenated coconut oil produced the greatest incidence of ventricular necrosis (79%) and that with choline‐supplemented cocoa‐butter the lowest (8%). Ventricular calcification was most extensive within the unsupplemented cod liver oil group (83%), most limited in the supplemented lard group (5%). In general, choline‐supplemented diets produced a lower incidence of cardiac damage. Little correlation existed between the composition and characteristics of specific fats and their activity in producing the specific cardiac lesi

ISSN:0002-9106    

DOI:10.1002/aja.1001240405

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

年代:1969

数据来源: WILEY

摘要:

AbstractOne of the fatty acid derivatives calledprostaglandins, PGB1, when applied to organ cultures of developing chick skin with feather organ loci, completely blocks feather organ development, but stimulates proliferation and keratinization of the epidermis. Control and PGB1treated explants were harvested after one, two, and three days in culture and processed for study by electron microscopy.Fine structural observation of control and treated skins indicate the following. (1) Tonofilaments appear much sooner in treated explants than in controls, and are distributed at all levels of the epidermis. (2) The cristae of mitochondria in epidermal cells of treated skins are long, closely apposed, and oriented parallel to the longest axis of the organelle as contrasted with a transverse orientation for them in control epidermis. (3) There is increased deposition of collagen in the mesenchyme of treated skins as contrasted to that observed in controls. (4) Unusual structures (inclusion bodies) occur throughout the stratified and superficial epidermis of treated skins and are composed of fine filaments and granules measuring about 30 Å in diameter. They are often associated with tonofilaments. (5) Small but numerous vacuoles appear in the epidermal cells of treated skins and seem to develop from cisternae of the Golgi apparatus or endoplasmic reticulum.The change in orientation of cristae of the mitochondria, vacuolation of the epidermis, and appearance of the inclusion bodies first occurs after two days of treatment with PGB1in culture. These observations coincide with previous data demonstrating that restitution of feather organ development can be accomplished after one day of treatment with PGB1, but not after two days of treatment.The observations are consistent with an accelerated maturation process, but may be correlated with a specific and irreversible change in a metabolic event necessary for feather development

ISSN:0002-9106    

DOI:10.1002/aja.1001240406

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe early sequelae of partial hepatectomy were studied at the ultrastructural level in livers of CFW mice that had been maintained on a normal diet or fed a fat‐free diet for four days prior to surgery. Normal‐diet animals showed a marked increase in number of small osmiophilic lipid granules in hepatocytes and the space of Disse during the first post‐operative hour and at all later intervals studied. This observation generally confirmed similar findings on C3H mice by Trotter ('65), but failed to provide conclusive indications of the source or direction of movement (i.e., from extracellular space into hepatocyte by engulfment, or from hepatocyte to extracellular space by secretion) of the granules in the space of Disse. In livers of fat‐free‐diet animals, where small lipid granules synthesized in the hepatocyte are recognizable by their osmiophobia (being derived from lipogenesis they are relatively highly saturated), synthesis and secretion by hepatocytes accounted for substantially all lipid granules appearing in the space of Disse during the first three postoperative hours and continued to occur during the fourth hour. This finding demonstrates the importance of the liver cell as a source of lipid granules (presumably very low density lipoproteins) appearing in the space of Disse after hepatectomy. Osmiophilic granules presumed to be of enteric origin, which were present in the space of Disse in very small numbers during the first post‐operative hours, increased in number during the fourth hour. The exact fate of these granules and their importance, if any, in the “post‐hepatectomy picture” could not be determined fr

ISSN:0002-9106    

DOI:10.1002/aja.1001240407

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

年代:1969

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001240401

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

年代:1969

数据来源: WILEY