摘要:

AbstractEnamel crystallites are electron opaque without osmium or heavy metal staining and give a crystalline electron diffraction pattern. Since the opacity and diffraction pattern are abolished from ultrathin sections of young enamel by floating on distilled water (Bishop and Warshawsky, 1982), the possibility that aqueous staining may also remove crystallites was tested. In addition, the effect of osmium postifixation on crystallite structure was examined.Rat incisors fixed by perfusion with a mixture of aldehydes were either nonosmicated or osmicated prior to dehydration. Incisor segments in the region of inner enamel secretion were embedded in the same Epon block to ensure reliable comparison. Osmicated enamel was more intensely stained with toluidine blue and more electron opaque than nonosmicated enamel. No other structural differences were seen. However, crystallites in osmicated enamel were more resistant to grid demineralization and electron beam damage. Routine staining was done by floating sections on solutions of uranyl acetate and lead citrate; sections were also floated on similar solutions from which the heavy metals were omitted. These solutions removed the electron opaque crystallites from the youngest enamel. Stained sections showed electron opaque crystallite‐like structure similar to unstained enamel. When sections that were extracted by the solutions from which the metals were omitted were restained, they appeared identical to routinely stained enamel. It was conclud that staining of young enamel removes the crystallites and reveals only the organic matri

ISSN:0003-276X    

DOI:10.1002/ar.1092070102

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe mouse epididymal duct can be histologically divided into five segments (I‐V), and the principal cells in segment II appear to secrete periodic acid‐Schiff (PAS)‐positive material into the lumen. In this study, male dd‐mice received one, two, or four 800‐R doses of radiation beginning at age 50 days. Mice receiving multiple doses were irradiated at 1‐week intervals.After irradiation, marked depletion of spermatozoa, or aspermia, occurred in the epididymal duct for 2 to 16 weeks after a latency period of 3 to 4 weeks according to the times of irradiations. During oligospermia or aspermia, PAS‐positive inclusions apeared in the principal cells in segment IV. The inclusions occupied a supranuclear position and appeared as round granules and globules measuring 2–15 μm in diameter, and increased in number, size, and staining intensity with time. They disappeared after reappearance of spermatozoa. The findings suggest that PAS‐positive material may bind to spermatozoa and, if not bound, is reabsorbed by the principal cells in segment IV and deposited as intracellular inclusions, and the prinicipal cells in segment IV and capable of digesting the accumulated PA

ISSN:0003-276X    

DOI:10.1002/ar.1092070103

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe influence of the Tabby gene on the submandibular gland of the mouse was assessed by comparing the mass of the gland, and its content of granular convoluted tubules, in prepubertal, pubertal, and adult Tabby mice and their wild type brother controls. The Tabby mice showed reduction in mass of the adult submandibular gland, delayed development of the granular convoluted tubules, and reduction in relative content of granular convoluted tubules. Epidermal growth factor (EGF) is released from the granular convoluted tubules of the mouse submandibular gland, and it is known to experimentally influence the devlopment of at least some of the structures that are affected by the Tabby gene. Accordingly, the question of a relationship between the Tabby gene and EGF is raised.

ISSN:0003-276X    

DOI:10.1002/ar.1092070104

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

年代:1983

数据来源: WILEY

摘要:

AbstractMouse fetal liver was studied ultrastructurally to identify and charaterize the developing hepatic parenchyma or prehepatocyte which may be responsible for producing the liver hemopoietic enviroment. It was observed that as the liver develops, there is close association of endodermal and mesenchymal cells in the region of the septum transversum. Numerous intercellular adhesions were observed between endodermal cells and mesenchymal cells. Twenty‐fours after endodermal and mesenchymal cells first intermingle, the liver extravascular space consisted of consisted of spherical hemopoietic cells dispersed among a heterogenous population of dark and light cells. The reticulum of prehepatocytes formed a three‐demensional cellular network which structurally supported the hemopoietic cells residing in the liver. By 12 days of gestation, prehepatocytes were a homogenous population of dark, stellate cells joined together by numerous intercellular adhesions. Broad areas of intercellular association were noted between processes and prehepatocytes and hemopoietic cells; however, no inercellular junctions between these two disparate cell populations were observed at this or any stage in development. Characteristics reflecting a cell population capable of synthesis and secretion of proteinaceous substances, namely, dilated Golgi apparati, increased numbers of polyribsomes and profiles of rough endoplasmic reticulum (RER), two types of vacuoles and/or vesicles, and intercellular microvillus‐lined spaces, were observed in the prehepatocytes between 12 and 17 days gestation. By day 17 of gestation, glycogen accumulation, biliary channel development, appearance of a subendothelial microvillus surface, nuclear shape and chromatin pattern, and arrangement of cytoplasmic organelles reflected the maturation of prehepatocytes into hepatocytes, the adult liver paren

ISSN:0003-276X    

DOI:10.1002/ar.1092070105

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

年代:1983

数据来源: WILEY

摘要:

AbstractThrough the combined use of peroxidase cytochemistry and examination at the ultrastructural level, the present study has identified liver hemopoietic foci containing three forms of erythropoietic cells, two forms of myelopoietic cells, and a population of peroxidase nonreactive cells within the extravascular compartments of mouse fetal liver. The nonreactive cells were 10 μm in diameter, displayed no peroxidase activity and were designated type I cells. This cell had an irregular nucleus, small profiles of rough endoplasmic reticulum (RER), a considerable population of monoribosomes and a few polyribosomes. The incidence of this cell type decreased significantly from 50% at 12 days gestation to approximately 10% of the hemopoietic cells at 17 days gestation. Type I cells could not be classified into a hemopoietic lineage and may represent undifferentiated hemopoietic stem cells. Three forms of erythropoietic cells, designated types II, III, and IV, were identified. These cells had a diffuse cytoplasmic peroxidase reaction, no peroxidase positive membrane‐bound organelles, and were approximately 7 μm in diameter. They corresponded to the more classically defined proerythroblast, polychromatophilic erythroblast, and nucleated normoblast, respectively. Types II and III had moderate cytoplasmic reactions, whereas type III, in addition, had a slight nuclear reaction. Type IV cells had a very dense cytoplasmic reaction but no nuclear reaction. Of the myelopoietic cells detected, one form had a slightly reactive Golgi and a few reactive granules. The other form possessed a clearly positive nuclear envelope (NE), RER, Golgi, and a population of reactive granules. The phagocytic sinusoidal lining cells (Kupffer cells) were peroxidase negative in contrast to similar cells in the rat. A population of peroxidasepositive granules was detected in fetal liver developing hepatocytes at 17 days gestation and increased in number with age. The morphology and organization of these various cell types in the liver hemopoietic environment are discus

ISSN:0003-276X    

DOI:10.1002/ar.1092070106

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe ultrastructural events in the establishment of the neuromuscular junction of the freely grafted extensor digitorum longus (EDL) muscle of the rat were studied 1–120 days after grafting. The original axons and muscle fibers, including soleplates, degenerated during the first few days, but Schwann cells and basal laminae persisted. Myofibers regenerated within the original basal laminae. Indentations of the sarcolemma, termed “presumptive synaptic clefts” (PSC), wer found on myotubes from 7‐day grafts. Schwann cells and residual acetylcholinesterase were invariably associated with the PSC, suggesting that the PSC developed at the site of the original soleplate. Nerves entered the grafts 10 days postoperatively and contacted the PSC of the regenerating muscle fibers on the 18–20th day. The secondary synaptic clefts of these “reconstructed” soleplates extended far beyond the subaxonal region. A second type of soleplate appeared on the 18–20th day. These soleplates were similar to those found in embryonic muscle and were considered to have been induced to form “de novo” by the presence of the nerves. When grafts were placed in permanently denervated limbs the “reconstructed” soleplates appeared, but the “de novo” type did not. These results shows that information directing the morphogenesis and innervation of the soleplate persists after the original muscle fibers and axons of a graf

ISSN:0003-276X    

DOI:10.1002/ar.1092070107

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe cellular localization and regional distribution of insulin‐and glucagonlike substance, C‐peptide‐like immunoreactivity, thiol:protein disulphide oxidoreductase, TPO (E.C.1.8.4.2.), and insulin/glucagon‐specific proteinase, ISP (E.C.3.4.22.‐), are studied in the CNS of man, adult and juvenile rats, mice, tortoises, and frogs by use of immunohistochemistry. Furthermore, the content of immunoreactive insulin, glucagon, and C‐peptide was estimated in human cadaver brains by radioimmunoassay.It could be shown that insulinlike immunoreactive material is widely distributed in the human brain and the CNS of juvenile rats as well as in mice, whereas in the CNS of adult rats and nonmammalian animals (frog, tortoises) the polypeptide is restricted to a few nerve cell populations. C‐peptide immunoreactivity was demonstrated in human CNS in the same nerve cells as insulin.By use of two different glucagon‐antisera it was revealed that gut‐type glucagon occurs in many nerve cells of human and mouse brains, as well as in the CNS of juvenile rats. On the other hand, pancreas‐type glucagon was less widely distributed in the human brain and nearly not detectable in the CNS of mice and rats.With the exception of neurosecretory nerve cells, there was a high degree of coincidence between the localization of insulin and TPO. The immunoreaction against the ISP antiserum was weak, but correlated well with the distribution of insulin‐immunoreactivity.The occurrence of TPO and ISP in the brain demonstrates the ability of nervous tissue to degrade insulin and glucagon. By radioimmunoassay it was established that human brain contains insulin, glucagon and C‐peptide at concentrations that exceed blood levels.We conclude from our data that, at least in part, cerebral insulin and glucagon are produ

ISSN:0003-276X    

DOI:10.1002/ar.1092070108

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

年代:1983

数据来源: WILEY

摘要:

AbstractCutaneous type I receptor sites (Haarscheiben or tactile domes) were examined at intervals of 4 to 275 days after chronic denervation of the skin. The number of domes decreased with denervation time, and only about one‐third of the domes originally present were still visible at 275 days. Most but not all of the Merkel cells from these domes were absent by 48 days, and the epithelium was significantly thinner than in nondenervated domes. Only a few of the examined domes appeared to be completely devoid of Merkel cells.It is concluded that after nerve transection, domes degenerate but do not always disappear entirely. The remmants may thus act as target sites which either attract regenerating type I nerve fibers or facilitate the formation of new dome structures after nerve regeneratio

ISSN:0003-276X    

DOI:10.1002/ar.1092070109

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

年代:1983

数据来源: WILEY

摘要:

AbstractThree methods are described for decreasing the statistical variance of stereological estimates.Methods 1uses profile boundaries and surface densities of nuclear membranes, measured in thin sections, to estimate the mean diameter, surface area, and numerical density of spherical and nonspherical nuclei. For the guinea pig pancreas (number(m) = 4), the standard deviations (s.d.) as a percent of the mean for the estimates of the diameters of the exocrine, duct, and endothelial cell nuclei were 1.5%, 3.3% and 1.4%. The estimate for the mean diameter of exocrine nuclei (6.4 ± 0.1 μm) was based on a spherical model, whereas the estimates for the diameters of the nonspherical (and nonconvex) nuclei of the duct (6.4 ± 0.2 μm) and endothelial (6.7 ± 0.1 μm) cells were calculated from the numerical density of the exocrine cells and the relative frequenceis of the three cell types (determined from serial reconstructions). In an average cubic centimeter, there were 6.17 × 108± 0.32 × 108(s.d. 5.1% of mean) exocrine cells, 1.64 × 108± 0.18 × 108(10.9%) duct cells, and 0.803 × 108± 0.13 × 108(16.6%) endothelial cells. In contrast to method 1, conventional stereological approaches were found to have standard deviations two‐to eightfold larger.Method 2uses a mean nuclear surface area and a ratio of surface densities to estimate the surface area of a membrane compartment in an average cell. A s.d. equal to 6.5% of the mean was found for the surface are of the outer mitochondrial membrane in an average exocrine cell (672 ± 43.6 μm2), which represented an almost fourfold reduction in the s.d. compared with an earlier estimate (Bolender, 1974).Method 3relates the surface area of a membrane compartment to a standard number of cells. Referenced to 106cells, for example, the surface area of the inner nuclear membrane of endothelial cells had a s.d. equal to 2.9% of the mean, whereas the surface density of the same membrane compartment—referenced to a cm3to cells—had a s.d. at 19.1% of the mean. In this case, method 3 produced almost a sevenfold reduction in the standard deviation. Similar results were found for exocrine and duct cells.The results of the study indicate that the standard deviation of a stereological estimate can be reduced to a miniumum by using a mean nuclear profile boundary to generate an estimate for a nuclear numerical density, which, in turn, can be combined with a surface density to obtain av

ISSN:0003-276X    

DOI:10.1002/ar.1092070110

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

年代:1983

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092070111

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

年代:1983

数据来源: WILEY