Journal of embryology and experimental morphology最新文献

{"title":"Lack of inactivation of a mouse X-linked gene physically separated from the inactivation centre.","authors":"M F Lyon,&nbsp;J Zenthon,&nbsp;E P Evans,&nbsp;M D Burtenshaw,&nbsp;K A Wareham,&nbsp;E D Williams","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Previous evidence had shown that, when a mammalian X-chromosome is broken by a translocation, only one of the two X-chromosome segments shows cytological signs of X-inactivation in the form of late replication or Kanda staining. In the two mouse X-autosome translocations T(X;4)37H and T(X;11)38H the X-chromosome break is in the A1-A2 bands; in both, the shorter translocation product fails to exhibit Kanda staining. By in situ hybridization, the locus of ornithine carbamoyltransferase (OCT) was shown to be proximal to the breakpoint (i.e. on the short product) in T37H and distal to the breakpoint in T38H. Histochemical staining for OCT showed that in T38H the locus of OCT undergoes random inactivation, as in a chromosomally normal animal, whereas in T37H the OCT locus remains active in all cells. The interpretation is that, when a segment of X-chromosome is physically separated from the X-inactivation centre, it fails to undergo inactivation. This point is important for the understanding of the mechanism of X-inactivation, since it implies that inactivation is a positive process, brought about by some event that travels along the chromosome. It is also relevant to the interpretation of the harmful effects of X-autosome translocations and the abnormalities seen in individuals carrying such translocations.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"97 ","pages":"75-85"},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14591271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The appearance and distribution of intermediate filament proteins during differentiation of the central nervous system, skin and notochord of Xenopus laevis.","authors":"S F Godsave,&nbsp;B H Anderton,&nbsp;C C Wylie","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Antibodies against various intermediate filament proteins have been used to follow cell differentiation in the early Xenopus embryo. Three new monoclonal antibodies against Xenopus cytokeratins raised against Triton-insoluble material from tadpoles (RD35/2a, RD35/3a and D3/3a), two antibodies against mammalian cytokeratins (LE65 and LP3K), monoclonal anti-(rat 200 K neurofilament protein), rabbit anti-(rat glial filament acidic protein), and rabbit antibodies to hamster and calf vimentin were used. We show that cytokeratins are present in the early central nervous system (CNS) and persist in the ependymal cells of the adult CNS. We also show that the notochord contains cytokeratin. The ontogeny of intermediate filament protein appearance in the CNS, skin and notochord between neural fold stage and swimming tadpole stage are described. These results are discussed in particular with regard to the use of the antibodies as differentiation markers.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"97 ","pages":"201-23"},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13580438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulation of extraembryonic calcium mobilization by the developing chick embryo.","authors":"R S Tuan,&nbsp;T Ono","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>During development, the chick embryo mobilizes the calcium it needs from two extraembryonic sources, first the yolk and then the eggshell. Since previous studies have strongly suggested that vitamins D and K may regulate chick embryonic calcium metabolism, we have examined here how these vitamins might be involved in regulating the calcium mobilization processes. We used as our experimental system chick embryos which were maintained in long-term in vitro culture in the absence of the eggshell. Our results showed that exogenous vitamin D3, in the form of the active 1,25-dihydroxylated metabolite, was hypercalcaemic in both control embryos and the calcium-deficient, shell-less embryos. Since the eggshell was absent in the latter, the vitamin D-induced hypercalcaemia must involve mobilization of calcium from the yolk and, or, the embryonic skeleton. The latter was unlikely since concomitant hyperphosphataemia was not observed. By radiolabelling the yolk with 45Ca2+ and subsequently monitoring its distribution, we showed that vitamin D3 stimulated yolk calcium mobilization. However, exogenous vitamin D3 did not appear to influence the calcium uptake activity of the chorioallantoic membrane (CAM), the tissue responsible for translocating eggshell calcium. On the other hand, when embryos were rendered vitamin K deficient by the administration of its antagonist, Warfarin, CAM calcium activity was significantly depressed, an effect which was remedied by vitamin K supplementation. We conclude that, during normal chick embryonic development, vitamin D is primarily involved in regulating yolk calcium mobilization whereas vitamin K is required for eggshell calcium translocation by the CAM.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"97 ","pages":"63-74"},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14911458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organ distribution of apolipoprotein gene transcripts in 6-12 week postfertilization human embryos.","authors":"B Hopkins,&nbsp;C R Sharpe,&nbsp;F E Baralle,&nbsp;C F Graham","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In the liver and the yolk sack of 6-12 week postfertilization human embryos, we have detected RNA transcripts from the following apolipoprotein genes: AI, AII, B, CII, CIII and E. The mRNA from the apolipoprotein CIII gene was relatively more abundant in the total RNA from the yolk sack than in that from the liver. The gut and adrenals contained transcripts of all these apolipoprotein genes apart from apolipoprotein AII. The kidneys and heart contained some apolipoprotein transcripts. In conjunction with previous studies, these results suggest that in the human embryo apolipoprotein genes are transcribed in a much larger range of organs than is the case in the adult. Many of these organs lack endoderm tissues.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"97 ","pages":"177-87"},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13580437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The differentiation of mouse gonads in vitro: a light and electron microscopical study.","authors":"S Mackay,&nbsp;R A Smith","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Indifferent urogenital complexes were excised from mouse foetuses assessed by developmental criteria as day 10.5 or 11. After 4 or 6-7 days in culture, complexes were fixed and examined by light and electron microscopy. The effect of culturing sexed complexes in mixed sex groups was investigated. The effect of the presence or absence of foetal calf serum in the culture medium was considered. No evidence of inhibition of one sex by the other was found. Ovaries developed further in cultures than testes.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"97 ","pages":"189-99"},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14911454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Axolotl retina and lens development: mutual tissue stimulation and autonomous failure in the eyeless mutant retina.","authors":"R Cuny,&nbsp;G M Malacinski","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>During eye development in the axolotl (Ambystoma mexicanum Shaw), morphogenetic movements bring together tissues from head epidermis, neuroectoderm and neural crest. The stages 0 to 14 of axolotl eye development were expanded from Rabl's (1898) stages 1 to 10 and correlated with Harrison's (1969) stages. At the onset of neurulation (stage 13 of Harrison), the head epidermis is already determined to form skin, and the neuroectoderm is committed to form brain, because these tissues develop autonomously in 60% Leibovitz L-15 culture medium. However, a sequence of mutual tissue interactions is necessary to stimulate eye development. When head epidermis and neuroectoderm were cocultured, eyes developed, containing retinas with photoreceptors (stage 8) and lenses with secondary lens fibres (stage 8). The first event needed in this case appears to be the secretion of a growth factor from the head epidermis which stimulates retina development from the neuroectoderm. When neuroectoderm cultures were exposed to nondialysable extracts (30 micrograms ml-1) of an adult epidermis derivative, the bovine cornea, pigmented retinas (stage 6) and at higher concentrations (3000 micrograms ml-1) neural retinas developed (stage 6). In turn, lens formation is stimulated in the head epidermis by a retina-derived growth factor. A mutation that causes adult eyelessness (e eyeless, nonlethal, recessive) affects the earliest event in eye development (stage 1a), while a mutation that causes arrest of eye development (mi microphthalmic, lethal, recessive) acts in a later event (stage 8). Two possibilities have been considered in the case of mutation e: either the head epidermis does not secrete sufficient amounts of active growth factor, or the presumptive retina itself is defective. The latter statement turned out to be correct, because mutant e neural plates rarely developed early retina stages (stage 5) in organ culture when combined with wild-type head epidermis. On the other hand, wild-type neural plates formed advanced retinas (stage 8) in all cases when combined with mutant e head epidermis. As expected, no retina or lens developed when both neural plate and head epidermis were from mutant e donors. The heterozygous presence of genes e and r (renal insufficiency, lethal, recessive) produces duplications of the presumptive retina at the optic stalk. This observation is consistent with the notion that the mutation e, assisted by the r locus, causes a primary failure in the presumptive retinal region.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"96 ","pages":"151-70"},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14922541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-organization of ependyma in regenerating teleost spinal cord: evidence from serial section reconstructions.","authors":"M J Anderson,&nbsp;C Y Choy,&nbsp;S G Waxman","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Multiple ependymal structures have been observed in regenerating spinal cord of the teleost Apteronotus albifrons. Evidence is presented for two modes of formation of the secondary ependymas: budding off from the primary ependyma, and de novo origin of a tube-like ependymal structure within a group of undifferentiated cells. Serial sections of regenerated cord provide evidence that undifferentiated cells not in immediate contact with the main ependymal layer can organize and differentiate into an ependymal structure in the regenerating spinal cord. These findings suggest that a significant amount of morphological organization can take place independent of the normal developmental sequence and environment.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"96 ","pages":"1-18"},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14922631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ciliary band formation in the doliolaria larva of Florometra. I. The development of normal epithelial pattern.","authors":"T C Lacalli,&nbsp;J E West","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The development of ciliary band pattern in the doliolaria larva of Florometra serratissima is described based on scanning and transmission electron microscopy. The uniformly ciliated epithelium of the post-hatching larva develops four regularly spaced bands over a period of approx. 20 h generating an epithelial pattern that is, essentially, a series of stripes. The first visible events of pattern formation progress over the larval surface in a posterior-to-anterior and dorsal-to-ventral sequence, but the initial pattern is not, in fact, striped. It instead consists of a close-packed array of oval interband domains separated and surrounded by belts of band cells. Secondarily the interband domains expand laterally and coalesce to form continuous, broad stripes, while the bands remain as narrow stripes between them. Two possible explanations for this unusual sequence of events are discussed: that it can be understood in evolutionary terms with reference to band pattern in other echinoderm larvae, and that it is a morphogenetic necessity because limitations inherent in the patterning mechanism prevent the direct formation of regular stripes.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"96 ","pages":"303-23"},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14924837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neurulation and the cortical tractor model for epithelial folding.","authors":"A G Jacobson,&nbsp;G F Oster,&nbsp;G M Odell,&nbsp;L Y Cheng","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>We present here a new model for epithelial morphogenesis, which we call the 'cortical tractor model'. This model assumes that the motile activities of epithelial cells are similar to those of mesenchymal cells, with the added constraint that the cells in an epithelial sheet remain attached at their apical circumference. In particular, we assert that there is a time-averaged motion of cortical cytoplasm which flows from the basal and lateral surfaces to the apical region. This cortical flow carries with it membrane and adhesive structures that are inserted basally and resorbed apically. Thus the apical seal that characterizes epithelial sheets is a dynamic structure: it is continuously created by the cortical flow which piles up components near where they are recycled in the apical region. By use of mechanical analyses and computer simulations we demonstrate that the cortical tractor motion can reproduce a variety of epithelial motions, including columnarization (placode formation), invagination and rolling. It also provides a mechanism for driving active cell rearrangements within an epithelial sheet, while maintaining the integrity of the apical seal. Active repacking of epithelial cells appears to drive a number of morphogenetic processes. Neurulation in amphibians provides an example of a process in which all four of the above morphogenetic movements appear to play a role. Here we reexamine the process of neurulation in amphibians in light of the cortical tractor model, and find that it provides an integrated view of this important morphogenetic process.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"96 ","pages":"19-49"},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14922544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of electric field on fusion rate and survival of 2-cell rabbit embryos.","authors":"J P Ozil,&nbsp;J A Modlinski","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Electric-field-induced blastomere fusion was studied in 2-cell rabbit embryos. Field strengths (1 to 3kV cm-1) and durations (35 to 1000 microseconds) were chosen so as to provide the right balance between fusion rate, viability and developmental capacity of embryonic cells. Maximum plasma membrane tolerance of 2-cell rabbit embryos was observed at about 3kV cm-1 for 1000 microseconds. All surviving 'fused' embryos were able to develop in vitro and most of them formed expanded blastocysts. Observation of 'fused' embryos immediately after fusion and during the whole cell cycle showed that 27.7% of the two diploid nuclei remained separated in the hybrid cell. More than one metaphase plate was formed at the onset of mitosis causing direct cleavage into three or four 'cells'. In the remaining embryos the two diploid nuclei seemed to form a common metaphase plate and cleaved into two equal blastomeres. After transfer to recipient does, 54.4% of these tetraploid embryos developed beyond implantation. Between day 11 and 20, ten live and morphologically fully normal embryos were recovered. Nine embryos were uniformly tetraploid and one recovered on day 18 was a diploid/tetraploid mosaic. The remaining implantation sites contained either abnormal, very retarded embryos or indefinable embryo remnants. After transfer of 'nonfused' embryos treated with 3kV cm-1, 49% gave birth to normal live young. These results suggest that the electric field can be applied successfully in a relatively wide strength and duration range without causing any visible teratogenic effect on treated embryos. Thus, tetraploid embryos can develop normally at least until two-thirds of pregnancy, but the question whether they are able to survive till term remains open.</p>","PeriodicalId":15708,"journal":{"name":"Journal of embryology and experimental morphology","volume":"96 ","pages":"211-28"},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14922546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}