摘要:

AbstractBecause normal growth as well as successful regeneration of the anuran tadpole tail depend upon outgrowth of the notochord, this process has been studied at the fine structure level to determine the mode of elongation of the regenerating notochord. The present work shows that inRana pipienscells at the apical region of the notochord send out numerous filopodia containing microtubules and microfibrils which may align with or attach to fibrillar bundles in the matrix of the fin. These apical cells adhere to each other at “primitive attachment sites” whereas the notochord cells at more anterior levels adhere more closely and show other specialized attachments; desmosomes, intermediate junctions and junctions of the gap or nexus type. A basement membrane is present near the tip, but is not continuous over the apical region. These findings suggest cell motility at the apex and possibly guidance by the fibrillar elements of the matrix. Therefore, the collagen fibers of the fin were examined by light microscopy after a number of fixation and staining procedures. No clearcut evidence of a regular antero‐posterior orientation of fibrils in the matrix of the fin which could guide outgrowth was found. Results are considered in connection with experiments on notochord regener

ISSN:0022-104X    

DOI:10.1002/jez.1401870112

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

年代:1974

数据来源: WILEY

摘要:

AbstractIf the functional volume of the rat urinary bladder is reduced by injecting varying quantities of a 50:50 melted mixture of paraffin and vaseline, the capacity of the bladder increases so as to provide the extra space needed to accommodate for the storage of urine. By four weeks, such bladders were found to have hypertrophied roughly in proportion to the size of the bolus of paraffin‐vaseline they containe

ISSN:0022-104X    

DOI:10.1002/jez.1401870113

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

年代:1974

数据来源: WILEY

摘要:

AbstractPulmonate snails (Helix aspersa) were raised from embryos to adulthood in total darkness. Unique ultrastructural features found in their photosensory cells were: 1. Break up of large aggregations of 800 A photic vesicles into smaller clusters by thick layers of membranes. 2. Increase in lipid droplets and in number and size of lysosomes. 3. Decrease in formation of photic vesicles by Golgi centers. 4. Flattening and bending of the tips of the microvilli. Tentative conclusions: the reduction in number of photic vesicles in dark‐adapted snails, by break down and decreased production, supports the hypothesis that the vesicles transport materials (photopigment ?) essential for light‐sensitivity of the microvi

ISSN:0022-104X    

DOI:10.1002/jez.1401870114

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe specific activities (and activity per organism) of L‐lactate dehydrogenase (LDH) and glycerol‐3‐phosphate dehydrogenase (G3PDH) were determined for developmental stages of the mosquitoAnopheles albimanus. The G3PDH specific activity is initially quite low, then undergoes a 5‐fold increase in the fourth instar larva. During the transitional pupal stage to adult, enzyme activity increases 25‐fold. The LDH specific activity in larval stages is initially about 100 times greater than that of G3PDH and reaches a peak in the late fourth instar larva. A 7‐fold decrease in LDH activity occurs just before moulting to early pupa. However, in contrast to reports forDrosophila, there is then a 3‐fold resurgence of LDH activity from pupal stage to the adult, mainly in the abdominal region. This is the same period in which G3PDH activity increases dramatically, primarily in the thorax. Thus, there is more than one pattern of gene expression for LDH and G3PDH within devel

ISSN:0022-104X    

DOI:10.1002/jez.1401870115

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

年代:1974

数据来源: WILEY

摘要:

AbstractIn mature unfertilized Rana pipiens oocytes a cytoplasmic substance exists that arrests mitosis at metaphase when injected into blastomeres. This is called “cytostatic factor (CSF)”. CSF is found to be inactive in fertilized eggs. CSF is extractable in a stable form with an extraction medium containing Ca++. In the absence of Ca++it is inactivated during storage. CSF is not dialyzable and precipitates in ammonium sulfate solution between 20 and 30% saturation. Heat treatment at 55°C for 30 min inactivates CSF. RNAase treatment inactivates CSF, but protease treatment does not. Roles of CSF and Ca++in oocyte activation at the time of fertilization are discu

ISSN:0022-104X    

DOI:10.1002/jez.1401870116

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

年代:1974

数据来源: WILEY

摘要:

AbstractA tail‐darkening reaction is described for tadpoles of the phyllomedusine frogs,Agalychnis dacnicolorandPhyllomedusa trinitatus. Tails are pale in the light because melanophores in the dermis of the fin are punctate. In darkness the melanophores become dendritic and the tail appears black. This photosensitivity is local since tail‐darkening in isolated tails and in intact tadpoles occurs equally well. Tails cultured for many days retain fully the capacity for tail darkening. Correlations between tail darkening and filter feeding and swimming are made from comparisons withXenopustadpo

ISSN:0022-104X    

DOI:10.1002/jez.1401870117

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

年代:1974

数据来源: WILEY

摘要:

AbstractOvulated ova in cumulus masses were obtained from rabbits following isoimmunization with rabbit sperm. They were inseminated in vitro with capacitated sperm, cultured and examined for cleavage and cumulus dispersion. In five experiments only 11 of the 81 (13.6%) ova from the immunized females cleaved compared to 15 out of 41 (36.5%) from the inseminated control females. The cumulus masses of ova from immunized donors dispersed more slowly than controls following insemination.

ISSN:0022-104X    

DOI:10.1002/jez.1401870118

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

年代:1974

数据来源: WILEY

摘要:

AbstractThis report presents results of a study inSchistocerca gregariaof large dorsal unpaired median neurons found previously in ganglia of several insects (Crossman et al.,171a; Hoyle, unpublished). Most of these neurons give off a single median neurite that makes a T‐branch, providing symmetrical left and right efferent axons. These axons emerge in ganglion nerve trunks and terminate in each of two nerves. They then travel to major skeletal leg muscles. One of the neurons supplies only the extensor tibiae (jumping muscle). The final branches of this neuron parallel the fast axon and supply muscle units that receive the fast axon only. All the muscle fibers in a unit are innervated (multiterminally) by the fast axon, but only a few receive terminals of the dorsal neuron in addition. The endings are of neurosecretory type, containing large numbers of dense core vesicles. Their function is unknow

ISSN:0022-104X    

DOI:10.1002/jez.1401870119

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe yolk proteins from severalDrosophilaspecies were identified and partially purified. One or two predominant proteins were found in the crude extracts of mature oocytes and in the hemolymph of mature females. They were absent or present in trace amounts in male and young female hemolymph. Fat body from matureD.silvestriscultured in Grace's insect culture medium, synthesized and released several proteins, two of which were precipitable by antibodies againstsilvestriscrude yolk extract. Fat body from immature flies synthesized and released only one of these proteins.

ISSN:0022-104X    

DOI:10.1002/jez.1401870120

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

年代:1974

数据来源: WILEY

摘要:

AbstractUrinary bladders of the euryhaline teleostGillichthys mirabiliswere maintained in organ culture under defined conditions for four days. Examination of bladders cultured in medium containing cortisol or prolactin or both hormones indicates that cortisol increases bladder water permeability and that prolactin antagonizes the cortisol effect, causing a reduction in water permeability. Bladders co‐cultured with teleost pituitaries or with teleost rostral pars distalis is show a pronounced reduction in osmotic permeability. The effects of prolactin and cortisol in vivo appear to be reproducible in vitr

ISSN:0022-104X    

DOI:10.1002/jez.1401870121

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

年代:1974

数据来源: WILEY