摘要:

AbstractRadiographs of right femora from 29 shrews (Blarina brevicauda) and 51 bats (27Myotis lucifugus, 14Pipistrellus subflavus) were analyzed to determine if bone in these small mammals conformed to Bassett's (′68) revision of Wolff's Law. Five external and four cortical dimensions were made on enlargements of radiographs of each femur. Comparative descriptions of the spongiosa are given.External dimensions appear to be determined genetically, and, in bats, are closely related to functional demands. Shrew femora retain a primitive mammalian morphology.No apparent relationship exists between animal weight and mid‐diaphyseal cortical thickness. Although differences in cortical thickness in bats suggest a possible relation between bone and pressure, no relationship is apparent in shrews; further, the comparative magnitude of these dimensions is similar in all three species, indicating genetic control mechanisms. Computations of maximal loading suggest that loading is so slight, that the inherent strength of bone tissue is adequate to resist mechanical deformation. However, there is evidence of cortical bone response to physiological demands.Inspection of the spongiosa also fails to provide evidence of conformity to Wolff's Law. Instead, the trabeculae appear to be related to physiologic factors, animal age, and inherited disposition patterns.Thus, there is no evidence that bone in these diminutive mammals responds to mechanical forces, and the applicability of Wolff's Law is not indicated. It is hypothesized that, as the mechanical forces are so minimal, intrinsic tissue strength is sufficient to resist mechanical deformation, and femoral anatomy in these species is dictated by genetic and inherent physiologic conditi

ISSN:0002-9106    

DOI:10.1002/aja.1001570102

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe Brattleboro strain of Long‐Evans hooded rats has hereditary hypothalamic diabetes insipidus due to the inability to produce antidiuretic hormone. Animals homozygous for this autosomal recessive trait have extreme polyuria and polydipsia, whereas heterozygotes are less severely affected. Light and electron microscopy were used to study the interstitial tissue of the renal papilla of Brattleboro rats and normal Long‐Evans rats. Staining with alcian blue or colloidal iron revealed that homozygous Brattleboro rats (DI) have greatly reduced quantities of glycosaminoglycans in the papillary interstitium. Heterozygotes showed staining similar but not identical to that of normal rats. The papillary interstitial cells of DI rats lacked the cytoplasmic processes seen in normal rats, and the normal relationship of these cells to the tubular elements of the papilla was absent. Electron microscopy revealed that the papillary interstitial cells of DI rats appeared less active than those of heterozygous or normal rats. In DI rats these cells displayed reduced numbers of lipid droplets and mitochondria, and the Golgi apparatus and rough endoplasmic reticulum were poorly developed. The altered ultrastructure of the papillary interstitial cells may be responsible for the reduction of interstitial glycosaminoglycans in DI rats. Glycosaminoglycans possess properties which may contribute to urinary concentration. It is suggested that the interstitial tissue of the renal papilla is influenced by antidiuretic horm

ISSN:0002-9106    

DOI:10.1002/aja.1001570103

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

年代:1980

数据来源: WILEY

摘要:

AbstractScanning electron microscopy (SEM) was used to investigate the development of the shoulder in the chick embryo. Initially the wing grows on an axis perpendicular to the dorso‐ventral and cranial‐caudal axes of the embryo, but soon begins to grow in a ventral and partially caudal direction. The change in axis of outgrowth occurs while the shoulder forms at the cranial proximal portion of the wing. Analysis of SEM observations, together with an analysis of serially sectioned embryos and photographs of live embryosin ovohas demonstrated that the shoulder continues to grow out on an axis perpendicular to the dorso‐ventral axis of the embryo, while the caudal and distal portions of the wing grow ventrally. The change in axis of outgrowth seems to be due to (1) the formation of the viscera under the wing, (2) the closing of themembrana reuniensto form a continuous sheet covering the viscera under the wing, (3) caudal movement of the duct of Cuvier and the cranial margin of the pleural coelom, and (4) ventral movement of the lateral body fold caudal to the wing. Although the visceral arches undergo major morphogenetic changes during this period, the visceral arches do not appear to have an influence on shoulder develo

ISSN:0002-9106    

DOI:10.1002/aja.1001570104

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe ultrastructure of nerve endings in the human prostate was studied using glutaraldehyde‐OsO4and KMnO4fixation. The nerve endings were classified into three categories according to the size of the vesicles and the contents of the synaptic profiles. In addition to the conventional adrenergic and cholinergic axons, a third type of axon profile containing a predominance of large granular vesicles was constantly found. Synaptic contacts were found only on smooth muscle cells. No epithelial innervation could be demonstrated. The functions and possible transmitters of the various types of axon terminals are discusse

ISSN:0002-9106    

DOI:10.1002/aja.1001570105

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe axial muscular system ofPontoporia blainvilleiis described and compared with published reports of this system in other cetaceans. A comprehensive system for classification of axial muscles is presented, based on the studies of Slijper. A discrete obliquus capitis inferior is described for the first time in cetacea, and it is suggested that its absence in previous descriptions may have been due partly to dissection error. The major axial muscle‐masses are organized in a similar way in most cetaceans, comprising a set of tail elevators and depressors, and a set of tendons with similar actions on the flukes. The anatomy of the axial musculature does not support the idea that the upstroke is the main propulsive stroke in cetaceans, but suggests similar roles of the upstroke and downstroke in propulsio

ISSN:0002-9106    

DOI:10.1002/aja.1001570106

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

年代:1980

数据来源: WILEY

摘要:

AbstractDuring an electron and light microscopic study of the equine intestinal epithelium, it was observed that some secretory granules of the undifferentiated crypt epithelium were incorporated into the nucleus during mitosis. A study was made of the chemical nature of the granules, using standard histochemical techniques: PAS‐Alcian blue, Deamination‐PAS, and Ninhydrin‐Schiff reactions. The granules contained a neutral protein‐polysaccharide complex with many terminal amino groups, possibly an antibody (IgA).The intranuclear granules underwent coalescence and degeneration during differentiation. The end‐product was identical with the nuclear bodies seen in other somatic cells and described in the literature. These nuclear bodies were seen in absorptive cells, goblet cells, and Paneth cells; but were not observed in any entero‐endocrine cells.This study shows that the nucleus is capable of isolating and degrading unwanted material, foreign and internally generated, and, further, it gives an explanation for the origin of nuclear bodies, structures that have long been an enigma in c

ISSN:0002-9106    

DOI:10.1002/aja.1001570107

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe effect of diet composition on diurnal changes in glycogen zonation patterns in rat liver was investigated in individually‐caged male Sprague‐Dawley rats adapted to the 2 + 22 controlled feeding and lighting schedule and to diets containing 30% casein/55% carbohydrates, 60% casein/25% carbohydrates, or 90% casein (30 rats/dietary group). Three rats from each dietary group were killed at the following times relative to the onset of feeding (0 min):−60, −30, 0, 15, 30, 45, 60, 90, 120, and 180 min. Glycogen in cryostat sections from the median and right lateral lobes of the liver was fixed and stained by standard techniques. The optical density of glycogen at points along the path between the central and portal veins of a given lobule was determined, and lobular glycogen gradients of replicate animals were integrated to form a composite lobular glycogen distribution profile. In the period from −60 to 0 min, liver glycogen levels were similar for rats on any of the diets, and the glycogen concentration was similar in periportal (P), midlobular (M), and centrilobular (C) hepatocytes. During the 0‐ to 45‐min period, diet‐related glycogen depletion occurred (90>60 ≫ 30% casein) by asymmetrical glycogen loss (P>M ≫ C hepatocytes) from the liver lobules. Similar food intake curves occurred for all diets. During the 45‐ to 180‐min period, asymmetrical glycogen accumulation began in lobular parenchymal cells (P>M ≫ C hepatocytes), and the rate of accumulation was related to dietary composition (30>60 ≫ 90% casein). The differential responses of parenchymal cells within liver lobules to physiological stimuli resulted in glycogen distributional changes that were rapid and of large magnitude. Our results are consistent with the hypothesis that periportal and midlobular hepatocytes are more metabolically responsive and active tha

ISSN:0002-9106    

DOI:10.1002/aja.1001570108

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe flexor digitorum profundus tendon of the rabbit hind limb is subject to tensional forces throughout most of its length but, within a localised area which is in contact with the calcaneum and talus, it is subjected to additional compressive forces. This pressure‐bearing area, in marked contrast to the tensional areas, has a fibrocartilage‐like organization and a high concentration of glycosaminoglycans (GAG).Ultrastructural features of the cells, collagen and matrix in the tension and pressure zones are also markedly different, with a full spectrum of transitional characteristics in the junctional region between the two zones. These findings support the concept that the cells in the various regions are sensitive and responsive to changes in physical load.In the tensional zone, elongated cells have extensive cytoplasmic flanges, which may contact flanges of neighbouring cells, and a scalloped cell surface that intimately conforms to the adjacent positively charged and tightly packed collagen fibrils of long periodicity (63 nm) and varying diameters. In the pressure zone, round and clustered fibrocartilage‐like cells, characterized by dense arrays of 11‐nm‐diameter microfilaments and numerous lipid droplets, are surrounded by loosely packed collagen fibrils of short periodicity (53 nm) and predominantly small diameters, and an extensive matrix rich in GAG.It is suggested that these regional morphological variations in the extracellular components result from, and are indirectly the cause of, changes in the cellular synthetic activities which are known to occur in response to changes in the physical en

ISSN:0002-9106    

DOI:10.1002/aja.1001570109

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe ultrastructure of gerbil parotid gland acinar cells studied by rapid freezing in liquid nitrogen and freeze‐substituting with OsO4was similar in general to conventionally prepared tissue, but different in several aspects. Acceptable preservation was limited to about 10 μm of the surface; the secretory granule membrane was a single dense line, while all others were trilaminar; the dense‐cored secretory granule had a rim of low density which was homogeneous; there were many continuous profiles between the Golgi lamellae, vesicles, and vacuoles; and mitochondria were long and arbor

ISSN:0002-9106    

DOI:10.1002/aja.1001570110

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

年代:1980

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001570111

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

年代:1980

数据来源: WILEY