摘要:

AbstractMouse eggs were parthenogenetically stimulated with hyaluronidase and osmotic shock and the resulting two‐, four‐ and eight‐cell stage embryos examined with the electron microscope. The ultrastructure of parthenogenones during cleavage showed numerous differences when compared with normal development. Cortical reaction was absent and there were no microvilli on the cell surface of developing blastomeres. The cytoplasm contained numerous bundles of fibrous material, vacuoles and lipid droplets, multivesicular bodies, and agglomerates of vesicles sometimes connected with cortical granules. Cortical granules and vacuolated mitochondria were numerous and usually situated near the cell membrane. The number of free ribosomes was very small and agglomerates of ribosomes or rough endoplasmic reticulum were not observed. Nucleoli in almost all cells were so‐called primary nucleoli consisting of a dense, osmiophilic core and narrow ring of granular material. In only a few cells was reticulation of nucleoli and formation of fibrillar and granular parts noticed. Nuclear fragments and nuclei with broken membranes were present in some cells. Primary nucleoli persisted during mitosis and were in close contact with chromosomes. Cytokinesis was irregular and small and large fragments of cytoplasm surrounded by membrane were often observed between dividing cells. Our results suggested that failure of parthenogenones to develop normally is probably caused by numerous disturbances during early cleavage. Incomplete cortical reaction, persistence of primary nucleoli, a probable disturbance in RNA and protein synthesis, and irregularities during nuclear and cellular division were observed in all

ISSN:0022-104X    

DOI:10.1002/jez.1401880102

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

年代:1974

数据来源: WILEY

摘要:

AbstractNonfertilized oocytes and 1‐, 2‐ and 4‐celled embryos were obtained from superovulated mice. The dry mass of cells was measured with an interference microscope either through the zona pellucida or after its removal with pronase. Volume was calculated from measurement of the diameter of the cells. From the dry mass/volume ratio the concentration of dry substance was calculated. Fertilization caused a drastic reduction in dry mass and volume from 34.6 to 31.4 ng and 189,500 to 165,000 μm3, respectively, while the concentration of dry mass of ova increased from 18.3 to 19.0 g/100 cm3. One‐celled embryos obtained 17, 23 and 34 hours after HCG gradually reduced their dry mass from 31.4 to 27.5 ng whereas their volume remained unchanged at the level of about 165,000 μm3. The increase of concentration after fertilization is followed by its reduction to about 17.0 g/100 cm3between 17 and 23 hours after HCG and later till 34 hours remains unchanged. Mean dry mass of the blastomeres of 2‐celled embryos is one half, whereas that of blastomeres of 4‐celled embryos is one fourth of the dry mass of 34 hours 1‐celled embryos. A pronounced diversity of both dry mass and volume of the blastomeres of the embryo after second cleava

ISSN:0022-104X    

DOI:10.1002/jez.1401880103

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

年代:1974

数据来源: WILEY

摘要:

AbstractMales were shown to be shorter‐lived than females in most species for which data have been avaiable. The present study, utilizing phenotypic sex‐reversal in various genotypes (XX,XY,YY) of the killifishOryzias latipes, suggests that males outlive females. The stress of producing many large eggs over the major part of the female's life was probably associated with their significantly shorter lifes

ISSN:0022-104X    

DOI:10.1002/jez.1401880104

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

年代:1974

数据来源: WILEY

摘要:

AbstractC. elegansresponds to several common chemicals. Comparisons of pairs of ions at equivalent concentrations indicated orders of attractiveness of:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm Na}^{\rm + } > {\rm K}^{\rm + } > 1/2 {\rm Mg}^{{\rm + + }} > 1/2 {\rm Ca}^{{\rm + + }} \\ {\rm Cl}^{\rm - } > 1/2{\rm SO}_{\rm 4} ^{ - - } > {\rm NO}_{\rm 3} ^ - > {\rm CH}_{\rm 3} {\rm COO}^{\rm - } \\ \end{array} $$\end{document}The least attractive pair of ions, calcium acetate, is attractive, indicating all these ions are attractive. The most attractive pair, sodium chloride, was attractive from a threshold of 0.1 mM to at least 50 mM. The response to NaCl was maximal throughout the temperature range 15 to 25°C and the pH range 3.0 to 9.0. Acid was avoided and base was attractive from concentrations of 0.1 to 1 mM. Dissolved CO2in the concentration range 0.1 to 1 mM was attractive in 10 mM sodium borate buffer, pH 8.8, but avoided in 25 mM potassium phosphate, pH 6.0. All these responses are likely to affect the distribution ofC. elegansin nature and they also provide a tool for promising studies in neurogenetics

ISSN:0022-104X    

DOI:10.1002/jez.1401880105

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

年代:1974

数据来源: WILEY

摘要:

AbstractWhen the eight most anterior segments ofEisenia foetidaare removed the wound is provisionally closed by a plug of coelomocytes surrounding an everted or retracted esophagus. Usually within one to three days the wound is definitively covered by migration of the columnar cells from the adjacent epidermis over the coelomic plug. Epidermal basal and gland cells do not directly take part in wound epithelialization.In the normal epidermis 2.3% of the cells incorporate3H‐thymidine during a labeling period of one hour. The incorporation rate for the columnar cells is higher than that for the basal cells and the gland cells are not labeled. During the period of wound covering by the epidermis (the first three days after transection) the DNA synthetic rate for basal cells and columnar cells drops steadily in both the segment bordering the wound and for at least four segments posteriorly. At four and five days the labeling rate for the epidermis of the segment near the wound rises sharply to beyond the control levels (3.7%) then drops again abruptly at six to seven days (0.8%). Two to four segments posterior to the wound the incorporation rate remains at the low 3‐day level throughout the first week after transect

ISSN:0022-104X    

DOI:10.1002/jez.1401880106

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

年代:1974

数据来源: WILEY

摘要:

AbstractTwo cephalopods,Sepia officinalisL. andLoligo vulgarisLam., have been investigated for soluble inhibitors of anti human blood‐group agglutinins. Only a weak inhibition was observed with respect to human anti‐A isoagglutinin. In the agar‐gel double diffusion test, however, the test substances showed a very strong precipitation reaction with heterophile anti‐A from snails. The precipitation lines were identical with that of A substance from peptone. The A‐like substances found were identified as glycoproteins containing terminal, non‐reducing bound α‐N‐acetyl‐D‐galactosamine. The biological importance of these macromolecules is discussed with particular reference to

ISSN:0022-104X    

DOI:10.1002/jez.1401880107

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe quantity of venom injected by a snake is one of the most important factors determining the danger of the bite. The present study tests whether the amount injected is in correlation with the size of the prey.Seven specimens ofVipera palaestinaeinjected with14C‐amino acids in order to label the venom, were offered three pairs of one mouse and one rat each. The amounts of venom injected into either prey were variable, ranging from zero to more than 200 mg. In most cases 50 mg were injected, approximately 8% of the total venom available in the glands. In three snakes the average amount injected into rats was two to three times higher than that injected into mice; in two snakes the mice received three to ten times more than the rats, while in two snakes there was no difference between the amounts injected into either prey.It is concluded that the size of the prey does not necessarily influence the amount of venom injected by the snak

ISSN:0022-104X    

DOI:10.1002/jez.1401880108

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

年代:1974

数据来源: WILEY

摘要:

AbstractAnemia induced experimentally either by administration of phenylhydrazine or by splenectomy stimulated spermatogenic and steroidogenic activities in the testes of the toad (Bufo melanostictus). It is concluded that the stimulated activity of the testes is mediated through the hypothalamo‐pituitary axi

ISSN:0022-104X    

DOI:10.1002/jez.1401880109

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

年代:1974

数据来源: WILEY

摘要:

AbstractAggregation factors isolated from the cell surface of five species of sponge are shown to be specific in their ability to enhance cell aggregation. Factors fromHaliclona viridis, Haliclona variabilis, Tedania ignis, Homaxinella rudis, andDysidea crawshayieach exhibit the species specific enhancing effect and have no such effect in heterospecific cell‐factor combinations. Radioactively labeled cell free supernatant materials are shown to bind selectively to homospecific cells suggesting that cells contain specific receptors for attachment of the aggregation mediating materials. Finally, in several heterospecific combinations there was an inhibition of cell aggregation. The inhibitory agent was separated from the enhancing factor chromatographically. After removal of the inhibitory substance, the enhancing factor was still active in promoting cell aggregation of the homospecific cells onl

ISSN:0022-104X    

DOI:10.1002/jez.1401880110

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

年代:1974

数据来源: WILEY

摘要:

AbstractThyroid‐like activity was investigated in the endostyles ofMolgula manhattensis, M. occidentalisandStyela plicata. Animals were immersed in sea water containing125I for one to 24 hours. Although electron microscopic autoradiography revealed an extracellular accumulation of silver grains associated with zone 8 in all three species and with zone 9 in two of them, intracellular accumulations were found only in zone 7. Within this zone in each of the three species, grains were present over the apical cell membrane, multivesicular bodies and the apical cytoplasmic matrix after brief exposure to125I. After longer exposure, grains were also present over large dense bodies and more basal regions of the cytoplasmic matrix.Certain features, suggestive of thyroidal functions, were observed in the cells of zone 7. These included morphological evidence for secretory and pinocytotic activities and cytochemical evidence both for peroxidase activity and for the presence of carbohydrate material which may represent a glycoprotein.It is concluded that active binding of iodine is restricted to zone 7 in the endostyles ofMolgulaandStyela, where it occurs at both the apical cell membrane and within multivesicular bodies. Some of the iodinated product may be immediately passed into the lumen of the pharynx. The rest is stored intracellularly within multivesicular bodies and dense bodies of zone 7. Intracellular binding and storage of iodine are considered to represent primitive conditions preceding the evolution of the follicular structure of the thyroid glan

ISSN:0022-104X    

DOI:10.1002/jez.1401880111

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

年代:1974

数据来源: WILEY