摘要:

AbstractOdontoblasts of developing rat molar teeth were treated with OsO4‐pyroantimonate to ascertain the localization of calcium. In addition, some tooth germs were incubated in solutions which were intended to allow for the escape of diffusible ions prior to fixation in OsO4‐pyroantimonate. In tissues treated directly with OsO4‐pyroantimonate, antimonate reaction product was found chiefly in abacus bodies and secretory granules of the Golgi region and in secretory granules in the distal pole of the cell. Lesser amounts of reaction product were found in the extracellular space, mitochondria, nucleus and generally throughout the cell. Tissues pre‐treated to allow for the escape of diffusible ions showed reaction product, identified as containing calcium, only in the abacus bodies and secretory granules.These results are considered to reflect the binding of calcium within the Golgi apparatus of the odontoblast. Moreover, since it has been shown by others that the abacus bodies and secretory granules contain collagen precursor, it is suggested that the collagen precursor is being seeded with calcium within the Golgi apparatus and that this intracellular calcium binding will play a role in facilitating the major wave of extracellular mineralization of the dentin which is to

ISSN:0002-9106    

DOI:10.1002/aja.1001470302

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

年代:1976

数据来源: WILEY

摘要:

AbstractA radioimmunoassay for glucagon, together with electron microscopic observations of early embryonic alpha cells were utilized to examine developmental aspects of glucagon accumulation and release in the chick embryo. Immunoreactive glucagon was detected in both the pancreas and blood plasma from the fifth embryonic day onwards. In addition, emiocytotic events were observed in alpha cells as early as the fifth embryonic day. The early appearance of glucagon and its subsequent developmental profile correlate well with major events in carbohydrate metabolism occurring in the embryonic chick, and are discussed in relation to a functionally responding system, the developing liver. The present data show that glucagon is secreted at earlier embryonic stages than hitherto demonstrated, and suggest a developmental role for glucagon in hepatic glycogen metabolism.

ISSN:0002-9106    

DOI:10.1002/aja.1001470303

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe auditory organ of the alligator lizard has been investigated with the transmission electron microscope using methods which distinguish between tight and gap junctions. There is a continuous zone of tight junctions located near the endolymphatic surface of the organ forming a boundary between the endolymph in scala media and the interstitial spaces between the cells. No such tight junctions were observed between the perilymph of scala tympani and the interstitial fluid within the organ. Small gap junctions occur between hair cells and supporting cells and large gap junctions occur between adjacent supporting cells. The locations of the tight junctions suggest that the composition of the intercellular fluid in the receptor organ is probably more like perilymph than like endolymph. The presence of gap junctions between hair cells and supporting cells provides a possible morphological basis for the occurrence of intracellular responses to sound in supporting cells, and for electric coupling of receptor cells.

ISSN:0002-9106    

DOI:10.1002/aja.1001470304

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe human diploid cell line, WI‐38, has proven to be an especially good object for high‐voltage electron microscopy using whole cells. Cells of intermediate passages were grown on plastic‐coated, carbon‐shadowed gold grids, fixed with glutaraldehyde, post‐fixed with osmium tetroxide, stained with uranyl salts and critical‐point dried. The absence of an embedding matrix produces images of increased contrast and resolution.The approach combined with stereo‐microscopy has extended our knowledge of cellular ultrastructure. Stereo‐images of whole cells reveal nuclei, mitochondria, microtubules, microfilaments, the endoplasmic reticulum and ribosomes in their expected forms. At high magnifications a continuity of microtubules, microfilaments and membranous elements with thin (3–6 nm) strands of the ground substance has been observed. These strands form a three‐dimensional lattice or mesh that pervades all parts of the cytoplasm. The entire structure is referred to as a microtrabecular lattice or mesh, the strands being the trabeculae. The inclusion of microtubules, microfilaments, ribosomes and vesicles of the endoplasmic reticulum within the material of the lattice makes them all part of a totally

ISSN:0002-9106    

DOI:10.1002/aja.1001470305

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

年代:1976

数据来源: WILEY

摘要:

AbstractPellets of glass (control), progesterone (P), testosterone (T), and estradiol‐17β (E) were placed on the mesentery or subcutaneously in the flank in ovariectomized (O) and ovariectomized‐hysterectomized (OH) mice, insuring that all or most of the hormone would pass through the superior mesenteric or circumflex iliac veins. After 21 days the diameters of these and of the ovarian, uterine, and femoral veins and inferior vena cava were measured at autopsy. T and E caused significant enlargement of the uteri; E was also responsible for bladder distention. The ovarian and uterine veins enlarged significantly in mice treated with T and E as compared to the controls. All other veins failed to respond to P, T, and E. The evidence demonstrates a specific response of ovarian and uterine veins in O and OH mice to T a

ISSN:0002-9106    

DOI:10.1002/aja.1001470306

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

年代:1976

数据来源: WILEY

摘要:

AbstractDigital corpuscles in the dermal papillae of the mouse toe pad have been studied using light and electron microscopy of serial thick and thin sections, and silver impregnations of frozen sections. These corpuscles are ellipsoid in shape and approximately 10–30 μm in diameter. They consist of one to three lamellar cells, nerve fibers and a capsule. These digital corpuscles are regarded as small Meissner corpuscles. The capsule is perineural epithelium. One or two myelinated nerve fibers and occasionally an unmyelinated nerve fiber enter the corpuscle. The axon terminals contain many mitochondria and a variable population of vesicular profiles. These terminals are ellipsoid or discoid in shape with the long axis parallel to the skin surface. The cytoplasmic plates (or lamellae) of the lamellar cells are arranged parallel to the skin surface, as is the cleft between the bilaterally symmetrical stacks of lamellae. Small processes extend from the expanded terminal of the neurite into the cleft between the lamellae. The relationship of the neurite terminal and associated lamellar cells resembles in some respects the organization of the inner core of Pacinian corpuscles. Intraepidermal fibers derived from myelinated neurites of the corpuscle may extend to the superficial epidermis. Intraepidermal fibers derived from unmyelinated neurites usually terminate in the basal regions of the epiderm

ISSN:0002-9106    

DOI:10.1002/aja.1001470307

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

年代:1976

数据来源: WILEY

摘要:

AbstractIn this study the entire epithelial lining of tracheas and a 15‐cm segments of small intestine were dissociated into individual cell components after 45‐minute incubation with 1% pronase. Light and electron microscopy of isolated cells confirmed good morphologic preservation of various epithelial cell types dissociated from the trachea and small intestinal mucosa.Of particular interest was the recovery and preservation of APUD endocrine cells, which are known to be widely dispersed amongst various non‐endocrine epithelial cells in both the trachea and small intestine. The APUD cells were demonstrated in dissociated cell preparations by a formaldehyde‐induced fluorescence method, Grimelius' silver nitrate stain, and electron microscopy. The isolated APUD cells retained their characteristic features, e.g., amine‐handling properties, argyrophilia and cytoplasmic dense‐core vesicles.The cell dissociation method described in this report provides high yields of viable epithelial cells in single cell suspensions which are suitable for further cell separation into homogeneous populations of single kinds of cells, including the APUD endocrine cells. Availability of methods for isolation of tracheal and intestinal APUD cells will facilitate further studies, in vitro, on secretory, metabolic and functional aspects of

ISSN:0002-9106    

DOI:10.1002/aja.1001470308

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe ultrastructure of developing canine parafollicular cells has been examined. The hypothesis that secretion is relatively inactive prior to birth but very active at and following birth was tested. Parafollicular cells develop and accumulate characteristic secretory granules prior to birth. However, there is little or no evidence of exocytosis at this time. At birth and during the neonatal period, but not in adult thyroids, sings of exocytosis of granular contents by parafollicular cells are abdundant. Just prior to the expected date of birth and before evidence of exocytosis appears, parafollicular cells accumulate intracisternal granules within rough endoplasmic reticulum. These observations are consistent with the view that parafollicular cells first become actively secretory around the time of birth and are more active at this time than in early fetal or later adult life.

ISSN:0002-9106    

DOI:10.1002/aja.1001470309

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

年代:1976

数据来源: WILEY

摘要:

AbstractKeratohyalin granules (KHG) from control and puromycintreated hamster cheek pouch epithelium were studied by electron microscopy. The animals were killed 1–4 hours after injection with 75–100 microgram puromycin per gram body weight; controls were injected with saline. The KHG from control animals were round or oval and consisted of a finely granular background matrix containing many small, round, homogeneous electron‐dense deposits. The KHG from puromycin‐treated animals showed marked variation in morphology and size. They consisted of a coarse granular or speckled matrix and round, club‐shaped or comma‐shaped electrondense deposits. Since puromycin is known to inhibit protein synthesis, alterations in KHG structure support previous reports suggesting the protein na

ISSN:0002-9106    

DOI:10.1002/aja.1001470310

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

年代:1976

数据来源: WILEY

摘要:

AbstractChondroblasts and retinal melanoblasts have been transformed with a temperature‐sensitive Rous Sacroma Virus. At permissive temperature the transformed cells do not display their unique phenotypic properties. When such transformed cells are shifted to non‐permissive temperature they do display their unique phenotypic propert

ISSN:0002-9106    

DOI:10.1002/aja.1001470311

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

年代:1976

数据来源: WILEY