摘要:

AbstractThe lysosomal enzyme acid phosphatase has been shown to increase in activity rapidly during the first 12 hours of cephalic regeneration in the planarianDugesia dorotocephala.This increase was correlated with the cytological demonstration of lysosomes in dedifferentiating cells and the electron microscopical cytochemical localization of acid phosphatase in lysosomes. These findings are interpreted as being consistent with the dedifferentiation hypothesis for the origin of blastema cells.

ISSN:0022-104X    

DOI:10.1002/jez.1401890202

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

年代:1974

数据来源: WILEY

摘要:

AbstractA glycoprotein resembling ovomucoid was purified from chorioallantoic membranes of 12.5 day chick embryos by a sequential procedure involving zinc chloride precipitation, hydroxylapatite chromatography, and ion exchange chromatography on DEAE‐ and CM‐cellulose. The resulting preparation was homogeneous as indicated by polyacrylamide gel electrophoresis at 3 pH values, isoelectric focusing, ultracentrifugation, and immunochemical analysis. The purified material had an isoelectric point of 4.8, molecular weight of 29,500 and contained 1.6 moles of galactose, 7.7 moles of mannose, 22.8 moles ofN‐acetylglucosamine and 0.4 mole of glucose per mole of protein. The ovomucoid fraction inhibited bovine trypsin, forming a 1 to 1 complex on a molar basis, and elicited a positive anaphylactoid response in albino rats at levels as low as 0.5 μg. A specific ovomucoid antiserum was obtained from rabbits that allowed investigation of the mobilization and metabolism of ovomucoid in the developing chick embryo. These studies revealed that between days 12 and 13 of embryo development a progressive migration of ovomucoid occurs from the albumin sac to the amnionic sac. The glycoprotein is then swallowed and transported through the gut to the yolk sac, where it is catabolized by proteases and glycosidases contained in the yolk sac membrane. Between day 12 of embryo development and day 7 after hatching, ovomucoid appeared in the serum of the chick and reached a maximum value of 2.4 mg % on day 18 of embryo devel

ISSN:0022-104X    

DOI:10.1002/jez.1401890203

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

年代:1974

数据来源: WILEY

摘要:

AbstractNeural crest precursors of dorsal root ganglia at lumbosacral levels of the spinal cord of chick embryos were destroyed by superficial cauterization at very early stages (52–64 hours) in order to study the influence of afferent input from the periphery on activity patterns of the hindlimbs during embryonic, hatching and post‐hatching periods. Neithertotalnorlocalactivity of the hindlimbs in deafferented chick embryos showed any significant difference quantitatively from those of control embryos between 9 and 17 days of incubation. These embryos exhibited typical prehatching and hatching behavior except the final climax stage of hatching in which the embryo normally cracks the shell around the air space and emerges. The experimental embryos were unable to hatch by themselves. In hatched chicks, legs were incapable of making alternate stepping movements. These observations, discussed in the light of other experimental evidences, suggest that afferent input from the periphery is probably involved in the patterning of coordinated activity of the legs in the ch

ISSN:0022-104X    

DOI:10.1002/jez.1401890204

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

年代:1974

数据来源: WILEY

摘要:

AbstractA study of the effects of deafferentation of the brachial level of the spinal cord in chick embryos was undertaken to examine the influence of afferent input on activity patterns of the wings, during embryonic, hatching and posthatching periods. Neural crest precursors of dorsal root ganglia were destroyed by superficial cauterization at somite levels 17 to 21 in embryos of stages 13–14. Between nine and 17 days of incubation no significant differences were observed in the frequency of wing movements as part of eithertotalorlocalactivity patterns. The prehatching and hatching behavior patterns were typical except that none of the experimental embryos managed to tuck the head under the right wing (tucking phase). Wing lifting and lowering were absent between day 18 and hatching. In hatched chicks, wings were incable of making synchronous bilateral flapping movements. The results indicate that afferent input from the wings to the spinal cord is probably involved in the patterning of wing movements. In the absence of afferent input, the chick embryos show gross disturbances in the pattern of behavior involving the wings during hatching and after hatchin

ISSN:0022-104X    

DOI:10.1002/jez.1401890205

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe purpose of this investigation was to determine the capacity for furrow establishment of the mitotic spindle in several kinds of dividing animal cells. To this end the cell shape was altered so that equatorial surface was brought in contact with the spindle and its normal geometrical relation with the asters changed. In flattenedTripneustes gratillaeggs, furrows formed at the tips of deeply cut notches that impinged upon the spindle area. InEchinarachnius parmaeggs, furrows formed at the tips of deeply cut notches and also at the margins of perforations that straddled the spindle. The distance separating the perforations was less than the normal spindle diameter. In flattened, dividing cultured newt (Diemictylus viridescens) kidney cells furrows formed in equatorial surface that was pushed inward far enough to displace the metaphase chromosomes. These results appear to indicate that the mitotic spindle of animal cells can establish furrows. We speculate that the actual role played by the spindle in normal cytokinesis depends upon the relative sizes of the asters and the spindle and upon the normal distance between the spindle and the equatorial surface.

ISSN:0022-104X    

DOI:10.1002/jez.1401890206

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

年代:1974

数据来源: WILEY

摘要:

AbstractBlastocysts were collected from the uteri of intact or ovariectomized mice and incubated with or without actinomycin D in a medium containing [14C] amino acids. In the absence of actinomycin D the rate of amino acid incorporation by blastocysts from intact mice (i.e., normal embryos) was constant; the rate of amino acid incorporation by blastocysts from ovariectomized mice (i.e., delayed implanting embryos) was initially low and increased to the normal value after four hours in vitro. In the presence of actinomycin D the rate of amino acid incorporation by normal embryos was only slightly reduced but the expected increase in the rate of amino acid incorporation by delayed implanting embryos was completely blocked. It is suggested that metabolic “activation” of delayed implanting mouse embryos requires the synthesis of new

ISSN:0022-104X    

DOI:10.1002/jez.1401890207

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

年代:1974

数据来源: WILEY

摘要:

AbstractEqual numbers of rabbit spermatozoa from the proximal cauda epididymidis and ejaculate of the same male were mixed and inseminated intravaginally. Their competitive performance in the same female was evaluated by identification of the two populations with x‐irradiation marking (fertilizing spermatozoon) and fluorescein isothiocyanate labelling (spermatozoa in the uterus and egg vestments). Following such mixed inseminations, epididymal spermatozoa from thirteen males fertilized 48% of 251 eggs recovered 50 hours after HCG injection and comprised 55%, 59% and 73% of spermatozoa in the perivitelline space, zona pellucida and mucin layer. When mixed spermatozoa from eight other males were inseminated 5 hours after HCG and the eggs were recovered 8 hours later (13 hours after HCG), epididymal spermatozoa accounted for 53% of the perivitelline and zona spermatozoa in 108 eggs and more than 50% of the uterine spermatozoa in seven of fifteen females. Cleavage of eggs fertilized by spermatozoa from the distal corpus epididymidis and ejaculate of the same male (eight males) was compared by insemination of the respective sperm populations into contralateral oviducts of the same female (sixteen females). There was no significant difference in the level of fertilization or the stage of cleavage 27 hours after insemination and HCG, whether eggs were fertilized by epididymal or ejaculated spermatozoa. These results indicate that once epididymal spermatozoa have acquired the capacity to penetrate the egg, they do not differ from ejaculated spermatozoa in their transport, capacitation, fertilizing ability or competence to sustain development of the egg to the sixteen cell stag

ISSN:0022-104X    

DOI:10.1002/jez.1401890208

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe effect of nerve growth factor (NGF) on hindlimb regeneration in postmetamorphicXenopus laevisfroglets was investigated. Two different dosage levels of NGF were tested on froglets whose hindlimbs had been amputated either above or below the knee joint. The course of regeneration in the NGF‐treated froglets was followed for 100 days post‐amputation.Treatment with NGF at a level of 2,500 Biological Units per froglet increases the extent of hindlimb regeneration attained compared with the controls, regardless of the level of amputation. On the other hand, a higher dose of NGF, 5,000 Units per froglet, does not alter the extent of hindlimb regeneration significantly. Treatment with NGF at either dosage does not appear to affect the shape or histological constitution of the regenerated limb segment. The general shape of the regenerate correlates with the level at which the limb was amputated. All regenerates obtained in this study conform to a common pattern in terms of histological constitution. They are composed of a central core of cartilage with a perichondrial membrane surrounded by a thin layer of connective tissue and covered by fully differentiated epidermis. No differentiated bone, muscle or nervous tissue was detected in any of the regenerates, but evidence of cartilage calcification was observed in limbs amputated below the knee. Possible implications of these results are discus

ISSN:0022-104X    

DOI:10.1002/jez.1401890209

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

年代:1974

数据来源: WILEY

摘要:

AbstractLength and weight of medaka appeared to be influenced by sex hormone‐treatment and genotype. Hormone‐treated genotypes were significantly shorter in length and slightly lighter in weight than untreated genotypes. The degree of response to androgenic and estrogenic treatment appeared to be strongly influenced by genotype. Growth of XX fish was stunted more by androgenic treatment than by estrogenic treatment. Growth of XY and YY fish was stunted more by estrogenic than by androgenic treatment. Differences in the metabolism of sex hormones by the three genotypes might be responsible for the variation in response to androgenic or estrogenic treatment. Sex phenotype, a unique interaction between genotype and exogenous hormone‐treatment, strongly influenced secondary sex character development (relative papillary size and nu

ISSN:0022-104X    

DOI:10.1002/jez.1401890210

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

年代:1974

数据来源: WILEY

摘要:

AbstractThis work aims to clarify whether methimazole‐induced sex transformation in tadpole ovaries is due to the goitrogenic property of the drug as some authors have suggested. Intact, thyroidectomized, and hypophysectomized female tadpoles ofRana catesbeianawere reared in 0.005% methimazole solution as experimentals; three parallel groups in tap water served as controls. After four months of goitrogen treatment, all six groups of tadpoles were sacrificed and their gonads sexed histologically. The results showed that intact, thyroidectomized, and hypophysectomized tadpoles in tap water had normal ovaries, while ovaries of intact, thyroidectomized, and hypophysectomized animals in methimazole solution were all transformed at least partially, and in some cases, almost completely to testes. Histologically, the process of sex transformation resulting from methimazole treatment was not different from that observed in heat‐treated tadpoles or in spontaneous sex reversals. These findings demonstrate that the hypophysis and thyroid were not involved in goitrogen‐induced sex transformation. This provides additional evidence in support of our belief that various factors, such as heat, sex hormones, gene action, and goitrogens though diametrically different per se, all deliver a direct and detrimental effect on the ovary, triggering a common pathway from destruction of oocytes to induction of rete cells which results ultimately in sex transform

ISSN:0022-104X    

DOI:10.1002/jez.1401890211

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

年代:1974

数据来源: WILEY