摘要:

AbstractThe single‐active‐X hypothesis states that in any mammal with more than one X chromosome per cell, only one X is active in each cell. The hypothesis further states that X‐chromosome differentiation occurs randomly in each cell early in development and subsequently is stable. The phenotype of a mammal heterozygous for a sex‐linked gene will thus be mosaic, and any interaction of different X alleles can occur only on the intercellular level. Another hypothesis, the “complemental‐X” hypothesis, explains the phenotype of a sex‐linked gene heterozygote in terms of intracellular allelic interaction.The validity of intercellular interaction in sex‐linked gene heterozygotes was tested in the mouse by making fusion chimeras of embryos carrying different X‐linked alleles and comparing the chimeric phenotype to that of a standard heterozygote.The X‐chromosome markerGreasy(Gs) was shown to affect ten parameters of hair structure, four of which were chosen to establish a series of hair types. It was found thatGs/ +. mice had almost the entire range of hair types, while wild‐type andGs/ mice showed restricted hair type distributions, significantly different from each other and fromGs/ +. It was also found that theGs/ + phenotype could not be accounted for by additivity of the wild‐type and mutant hair‐type distributions.Some of the fusion chimeras had phenotypes similar, if not identical, to that of standardGs/ + mice in all respects except the rate of change in the distribution of hair types with age. This discrepancy could be accounted for on the basis of cell selection.These data support the conclusion that intercellular interaction can account for the observed phenotypes of se

ISSN:0022-104X    

DOI:10.1002/jez.1401810102

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

年代:1972

数据来源: WILEY

摘要:

AbstractIn the past, studies of avian limb morphogenesis emphasized epithelial‐mesenchymal tissue interactions and problems of determination of limb symmetry. In contrast, a recent hypothesis, based on studies of the aggregation rates of dissociated cells and on computer modeling, proposes that the paddle shaped polydactylous limb of thetalpid3mutant is the result of increased intercellular adhesion of limb bud mesoderm cells during limb development. The notion that differences in intercellular adhesion may have profound effects on limb morphogenesis has not been critically explored previously.The present experimental approach includes studies of cell sorting in aggregates containing bothtalpid2and wild‐type cells. In this system, adhesive differences should result in cell sorting. Instead, cell sorting did not occur, indicating by this test at least, that limb bud mesoderm cells oftalpid2and wild‐type embryos are equally adhesive. This conclusion finds support from studies involving tissue spreading in fused fragments oftalpid2and wild‐type limb bud mesenchyme tissue and in studies of kinetics of aggregation of dissociate

ISSN:0022-104X    

DOI:10.1002/jez.1401810103

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

年代:1972

数据来源: WILEY

摘要:

AbstractA seven step series of whole body irradiations beginning with 1,872 R and ending with 20,000 R showed that 10,000 R is not sufficient to block posterior regeneration from the fiftieth segment in the barnyard earthworm,Eisenia foetidabut that 20,000 R is completely effective.With partial body irradiation at 20,000 or 30,000 R, if the five segments adjacent to the cut surface are exposed and the rest of the body shielded, there is no regeneration by the end of four weeks when controls have regenerated a mean of 34 segments and a minimum of 23 and stopped forming new ones. At the end of seven or more weeks all the partially irradiated worms had recovered and regenerated up to means of 17.3, 20.0, and even 26.3 segments.An abscopal effect was clearly evident in worms in which the first 40 segments were irradiated and the rest of the body, including the ten segments adjacent to the cut surface, shielded. All such worms regenerated without appreciable delay but markedly fewer segments than the controls. The question then arises as to why regenerating blastemas which are fully competent to regenerate a mean of 25 segments do not continue to proliferate until they have formed about 35 like the controls.

ISSN:0022-104X    

DOI:10.1002/jez.1401810104

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

年代:1972

数据来源: WILEY

摘要:

AbstractIntraspecific transplantation of ovaries in 18 species of cockroaches resulted in the initiation of yolk formation and oocyte growth rates similar to sham‐operated controls. Host vitellogenins were sequestered by transplanted oocytes in concentrations equal to those observed in oocytes of unoperated cockroaches. Ovaries transplanted interspecifically sequestered host vitellogenins and grew to terminal stages only when donor and host were closely related. Yolk formation did not occur when ovaries were transplanted between species of different superfamilies or families, whereas several cases of successful ovary transplantations were observed between species of different subfamilies. Unsuccessful transplants either failed to take up host vitellogenins and did not increase in size or were encapsulated and degenerate

ISSN:0022-104X    

DOI:10.1002/jez.1401810105

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe question was asked whether the proximo‐distal regional organization of regenerating urodele limbs is the result of an epidermal‐mesodermal interaction, as is the case in the embryonic limb bud. Epidermal deletion experiments on regeneration blastemas of various stages have answered this question in the affirmative. The mechanisms involved in the morphogenesis of the regeneration blastema are therefore very similar to those operating in the morphogenesis of embryonic limb b

ISSN:0022-104X    

DOI:10.1002/jez.1401810106

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

年代:1972

数据来源: WILEY

摘要:

AbstractInZonotrichia leucophrys gambeliicomplete testicular development is induced in captive males subjected to long daily photoperiods. In identically treated females ovarian development is only partial. This partial development of the ovary, and the subsequent premature regression thereof, correlate with changes in activity of the “acetylcholinesterase cells” of the pars distalis. This adds to the evidence that these cells are gonadotro

ISSN:0022-104X    

DOI:10.1002/jez.1401810107

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

年代:1972

数据来源: WILEY

摘要:

AbstractAblation of the olfactory bulbs terminates the sexually oriented behavior patterns shown by the male hamster towards the female. All aspects of overt copulatory behavior including mounting are immediately eliminated. Investigatory behavior is decreased significantly and orientation of attention to the hindquarters of the animal being investigated (sexual orientation) is lost over a one to two week interval. This disruption of sexually oriented behavior patterns occurs regardless of the degree of experience of the male in mating prior to the bulbectomy. Unilateral bulbectomy or sham bulbectomy does not disrupt, even temporarily, the mating pattern.Evidence that the lack of mating behavior following bulbectomy is indeed due to anosmia was provided by rendering animals temporarily anosmic by use of zinc sulfate in the nasal cavities. Full recovery of sexual activity occurred within four to six days following this treatment. A second treatment produced a similar result.Naive males, raised in isolation, can show a normal copulatory pattern on first exposure to a receptive female. Naive males do not distinguish between diestrus (non receptive) and estrus (receptive) vaginal secretions from the female.The release of sexual arousal requires olfactory input in the male hamster, conditioning to other cues does not occur. However, differentiation between receptive and non‐receptive females appears to be a positive learned response. The absolute dependence of the male hamster on olfactory cues for sexual arousal has an obvious adaptive value in a species where the female tends to be dominant in encounters and the male, if unable to escape, can be maimed or killed during the course of a figh

ISSN:0022-104X    

DOI:10.1002/jez.1401810108

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe addition of low levels of serotonin (20–50 μg/ml) to the rearing medium of sea urchin embryos specifically inhibits the hatching process by blocking the synthesis of an active hatching enzyme. Other developmental processes seem to be unaffected. Embryos are sensitive to serotonin during the first three cleavage divisions only. The uptake of RNA and protein precursors, and the rate of RNA synthesis are unaffected by serotonin, whereas the rate of protein synthesis is elevated by approximately 45% during the 2‐cell to 16‐cell interval of development.The addition of higher levels of serotonin, 75 and 100 μg/ml, causes retardation and blockage of cleavage division respe

ISSN:0022-104X    

DOI:10.1002/jez.1401810109

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

年代:1972

数据来源: WILEY

摘要:

AbstractNineteen of 33 or 58% of six‐day blastocysts, recovered from four female rabbits demonstrated an apparent male chromosomal complement with a minute Y chromosome. The remaining 42% of the blastocysts had a normal female XX chromosomal complement. All four female rabbits, two California and two New Zealand White, were inseminated by a particular California male rabbit. Chromosome studies of peripheral blood cultures from the male, which had normal gonadal and genital anatomy as well as normal fertility, revealed a karyotype identical to that seen in the blastocysts with the apparent male chromosomal complement. Autoradiographic studies from blood cultures of the male indicated that the minute chromosome was late‐replicating and was most likely the Y chromosome. The suggestion is made that the rabbit may be another mammal with Y chromosome polymorph

ISSN:0022-104X    

DOI:10.1002/jez.1401810110

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

年代:1972

数据来源: WILEY

摘要:

AbstractTimed‐sequence studies of scaleless anterior shank skin have shown that both histogenesis and morphogenesis are abnormal. An epidermal placode does not form in the mutant and thus the subsequent morphogenetic movements of placode into scale ridge are blocked as well. The dermis of the anterior shank remains flat rather than forming overlapping ridges. Two histologically distinct epidermal surfaces (outer and inner) are formed on either side of a normal scale ridge. In scaleless only a single epidermal surface develops and this is unlike either surface of a normal scale. An isolated dermal ridge of 16‐day normal embryonic scale can induce eight‐day chorionic epithelium to form both the outer and inner epidermal surfaces. Scaleless dermis of the same age when recombined with eight‐day CE will induce an epidermis typical of the normal outer scale surface, but no inner epidermal surface is formed. Previous studies have shown that the genetic defect is expressed in the epidermis and that at earlier stages scaleless dermis can, when associated with a normal epithelium, participate in placode formation and histogenesis of both epidermal surfaces. It seems reasonable to conclude that placode formation is initiated by the epidermis which thereby establishes heterogeneity in the scale dermis; thereafter, the scale dermis directs the histogenesis of the two epidermal s

ISSN:0022-104X    

DOI:10.1002/jez.1401810111

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

年代:1972

数据来源: WILEY