摘要:

AbstractOur previous work gave evidence that leopard frogs (Rana pipiens) possess inducible killer (IK) cells (CTL‐like) and spontaneous killer (SK) cells (NK‐like) that can destroy allogeneic RBC. To further characterize these cytotoxic cells we have examined their ultrastructural morphology and effector cell‐target cell membrane contacts. We also studied the sensitivity of these two effector cells to low temperature (4°C). Our results showed that SK effector cells are lymphocytes (10 μm) which contain numerous vacuoles and osmiophilic granules, while IK effectors are another lymphocyte population (up to 12 μm) with a small amount of cytoplasm and few mitochondria. Both IK‐ and SK‐mediated lytic responses were suppressed significantly by low temperature. These observations allow us to propose that frog SK and IK cells may be homologous to mammalia

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00909.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLevels of vanadium, sulphur and bromine within the vanadopohores of Ascidia mentula vanadocytes have been determined by quantitative X‐ray microanalytical techniques. Values obtained for vanadophore vanadium in thin sections correspond to 2.5‐3.25% or 0.5‐0.65 molal aqueous solutionsin vivo.Quantitation of sulphur in thin sections gives levels an order of magnitude lower than for vanadium, but it is likely that major losses of sulphur have occurred, since analysis of unfixed, air dried vanadocytes gives V/S atomic ratios close to unity. This 1: 1 ratio may have implications for the structure of the vanadium complex. Quantitation of bromine is less reliable, but levels of this halogen in vanadocytes are significant. The possibility that bromine, in the form of brominated metabolites, together with vanadium and acid, contribute to a multicomponent chemical defense role in ascidians is disc

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00910.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFour endocrine cell types were identified ultrastructurally in the pancreas of the grass lizard,Mabuya quinquetaeniata.These cells were similar in shape, location and frequency to the previously described B‐, A‐, D‐ and PP‐cells. The secretory granules of the B‐cells were round or oval in profile, with an internal core of variable shape. The mean diameter of the B‐cell granules was 780 nm (range 350–1000 nm). The A‐cell granules were round, oval or irregular in shape and highly electron dense, with a narrow electron lucent space between the core and the limiting membrane. The mean diameter of these granules was 450 nm (range 200–750 nm). The D‐cell granules were round, oval or irregular and of moderate electron density, with an average diameter of 340 nm (range 200–500 nm). The limiting membrane was closely apposed to the core or separated from it by a narrow lucent space. PP‐cell granules were round with high electron density and with a narrow space between the core and the limiting membrane, and their average diameter was 150 nm (range 50–350 nm); these secretory granules accumulated at the cytoplasmic process. Tracing of the cytoplasmic processes of PP‐cells in serially cut ultrathin sections revealed that most of these processes ended in the vicinity of blood capillaries, indicating that the PP‐cells were en

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00911.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractUltrastructural studies were performed on the blood cells ofPlanorbarius corneus.Spreading and round cell forms were observed. The spreading form can be distinguished from the round form by its abundant cytoplasm, pseudopods and irregularly shaped nucleus. Electron dense granules in the mitochondrial matrix are found in the round form and are lacking in the spreading form. Moreover, cellular apoptosis is observed in the round form. The ultrastructural findings and the previously described characteristics support the idea that the two cell forms belong to two basic cell types.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00912.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn vitroexcystation of metacercariae ofClinostomum complanatum(Rudolphi, 1819) was studied. Excystation was an active process, initiated by a rise in temperature. The metacercariae excysted in enzymic as well as non enzymic medium, but the rate of excystation was affected by the temperature and/or pH of the medium. The optimal excystation was obtained in pepsin‐Tyrode at pH 2.3‐3.5 and a temperature of 42°C. Trypsin treatment was not requ

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00913.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe utricular macula in the inner ear was examined in two turtle, two lacertilian, two snake and one crocodilian species. The orientation of hair cells was found to be similar to the general pattern for this macula described previously from fish to mammals. The calyceal hair cells, characterized by their embracing afferent nerve endings, are distributed in a single belt running parallel with the anterior and lateral borders of the macula in the examined reptiles.The number of hair cells in a large number of calyces was counted for some of the examined reptile species, and the total number of hair cells calculated in two specimens of a turtle, crocodile and snake utricular macula. In the turtle and snake maculae, the calyceal hair cells form about 10% of the total hair cell number, while the crocodiles, which were very young, only had 2% calyceal hair cells. The total number of hair cells was found to be much higher in the crocodiles than in the other reptiles examined. The presented data, as well as data from the literature of the avian and mammalian inner ear, indicate that the number of this very sensitive hair cell type in the utricular macula is independent of locomotion type.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00914.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe organization of the nervous system and the histology and ultrastructure of the apical disc and the pyriform organ have been investigated by serial sections with light and electron microscopy for the larva of the vesiculariid ctenostome bryozoanBowerbankia gracilisLeidy 1855. The nervous system consists of four major internal components: (1) a median‐anterior nerve nodule; (2) an equatorial, subcoronal nerve ring; (3) paired aboral nerve cords; (4) paired antero‐lateral nerve tracts. The nervous system is associated with the ciliated larval surface at the apical disc, the pyriform organ, the corona and the intercoronal cells. The paired aboral nerve cords extend from the apical disc to the nerve nodule, which gives rise to the paired antero‐lateral nerve tracts to the pyriform organ and to paired lateral tracts that form the equatorial nerve ring. Ultrastructural evidence is provided for the designation of primary sensory cells in the neural plate of the apical disc and in the juxtapapillary regions of the pyriform organ. Efferent synapses are described between the equatorial nerve ring and the overlying coronal cells, which constitute the primary locomotory organ of the larva. The repertoire of potential functions of the apical disc and pyriform organ are discussed. It is concluded that the apical disc and pyriform organ constitute larval sensory organs involved in orientation and substrate selection, respectively. Their association with the major effector organs of the larva (the corona and the musculature) via the nervous system supports this interpret

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00915.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY