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  • 1
    Electronic Resource
    Electronic Resource
    Changes in the interior surface of newly mesodermalized ectoderm and its contact activity with competent ectoderm in the newtCynops (Amphibia) (1991)
    Springer
    Development genes and evolution 199 (1991), S. 413-422 
    Details
    ISSN: 1432-041X
    Keywords: Mesodermalization ; Neural induction ; Amphibia ; Cell contact ; SEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The presumptive ectoderm (pE) ofCynops gastrulae was artificially mesodermalized by contact with teleost swimbladder. The newly mesodermalized ectoderm (mE) acquired the capacity for neural induction (Suzuki et al. 1986a). SEM observations revealed that the mE cells altered their cellular profiles immediately after mesodermalization. The characteristics of the cell surface and the cell architecture became similar to those of invaginated mesoderm cells. There were distinct differences in the cellular contact between mE—pE and pE—pE combinations. The mE-pE combinations kept close contact at their interior surfaces, while the pE—pE combinations did not keep contact. Both TEM and SEM observations also indicated that there were tight contacts between mE and pE cells. These findings suggest that neural-inducing activity of the newly mesodermalized ectoderm cells is coupled with acquisition of cellular affinity toward the interior surface of competent ectoderm cells, and probably requires close cell contacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01705852
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  • 2
    Electronic Resource
    Electronic Resource
    Attraction of chick primordial germ cells by gonadal anlage in vitro (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 215 (1986), S. 403-406 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The attraction of primordial germ cells (PGCs) by the gonadal anlage (germinal ridge; GR) in vitro has been demonstrated in the chick. PGCs were isolated from circulating blood of stage 13 embryos (Hamburger and Hamilton, 1951), placed between the GR and other embryonic tissues (neural tube, heart, allantois, liver) as controls separated by a distance of 170 μm on collagen-coated substrate, and cultured with modified medium 199 (Kuwana and Fujimoto, Anat. Rec., 209:337-343, 1984) containing 10% fetal calf serum (pH 7.3). The behavior of PGCs was observed for 3 hr by 16-mm time-lapse microcinematography.PGCs showed directional movement toward GR. Also, there was a stronger attractive effect on the PGCs by GR from stage 13 embryos than by GR from later stage embryos. These results suggest that PGCs are attracted by some factor emitted from GR.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092150411
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  • 3
    Electronic Resource
    Electronic Resource
    Locomotion and scanning electron microscopic observations of primordial germ cells from the embryonic chick blood in vitro (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 209 (1984), S. 337-343 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The locomotion of chick primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography and 35-mm timelapse film. The PGCs isolated from circulating blood of stage 14 to 16 embryos (Hamburger and Hamilton, 1951) were cultured on a substrate of mesenchymal feeder cells obtained from the dorsal mesentery of stage 40 embryos, using modified medium 199 containing 10% fetal calf serum. The PGCs were found to move actively and to show a tendency to move along the longer axis of the underlying cells. The velocity of PGC locomotion averaged 26 μm/hr and reached 58 μm/hr as a maximum.After observation, the PGCs were processed for scanning electron microscopy. They had a considerable number of microvilli about 0.2 μm in thickness and some cytoplasmic blebs on their surfaces. It was observed that the PGCs in the migrating phase adhered to the substrate with its filopodia only at the leading edge, while a large part of the cell appeared to be apart from the substrate.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092090312
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  • 4
    Electronic Resource
    Electronic Resource
    Active locomotion of human primordial germ cells in vitro (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 205 (1983), S. 21-26 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The locomotion of human primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography. PCGs dissociated from 5- to 6-week human embryos were cultured in vitro using L-15 medium and human cord serum, and their movement on three artificial and two natural substrates was compared. Three-dimensional collagenous fiber nets reconstructed in the culure dish were found to be appropriate for PGC movement, although the cells did not migrate actively on any of the other substrates. The PGCs moved actively in an amoeboid fashion, extending pseudopodlike cytoplasmic processes toward the direction of movement. The direction of PGC locomotion was random. One PGC showed the most active motility; the velocity of the cell locomotion averaged 25 μm/h and it became extremely elongated, measuring 92 μm in its longer axis, whereas in the stationary state the PGC was rounded and measured 20 μm in diameter. Thus, the present study offers evidence that human PGCs can migrate actively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092050104
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  • 5
    Electronic Resource
    Electronic Resource
    Behavior of chick primordial germ cells moving toward gonadal primordium in vitro: Scanning electron microscopic study (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 219 (1987), S. 164-170 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Primordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16-mm time-lapse filming or time-lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed.With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: (1) The PGC produced a small pseudopodium. (2) This pseudopodium enlarged to the GR, and PGC-substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. (3) Finally, the PGC as a whole moved toward the GR, being trailed by the process.The locomotion of the PGC on the thick collagen layer as a three-dimensional substrate was as follows: (1) The PGC protruded a pseudopodium in the direction of the GR. (2) This pseudopodium elongated through the collagen network. (3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. (4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PGC in vivo.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092190209
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  • 6
    Electronic Resource
    Electronic Resource
    Extragonadal distribution of primordial germ cells in the early chick embryo (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 222 (1988), S. 90-94 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chick primordial germ cells (PGCs), after separation from the endoderm in early embryonic development, temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. It has been noted by some authors that some PGCs are present in extragonadal sites in some vertebrates. In the present study, we examined the distribution and localization of PGCs in extragonadal sites in the chick embryo. PGCs were identified by periodic acid-Schiff staining with light microscopy. In embryos at stages 20-24 (PGCs are in the settlement stage in the gonadal primordium), approximately 20% of the total number of PGCs were observed in extragonadal regions. Approximately 90% of these ectopic PGCs were found in the head, mainly in the mesenchyme surrounding the neural tube. Even at stage 14 when PGCs were usually circulating in the blood vessels, some of the PGCs had emerged from the blood vessels and were detected in the extragonadal site. The pattern of distribution of ectopic PGCs in the head area is probably attributed to the earlier, dominant development of the capillay network, and to the sluggish capillary blood flow in that region, which allows intravascular PGCs to escape into the tissue.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092220113
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  • 7
    Electronic Resource
    Electronic Resource
    Ectopic colonization of primordial germ cells in the chick embryo lacking the gonads (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 229 (1991), S. 109-115 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chick primordial germ cells (PGCs) first appear in the extraembryonic region in the early embryo, then temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. In the present study, we examined the trend of ectopic distribution of PGCs in the chick embryo when its future gonadal region had been removed a t an early stage. Embryos at stage 10, from which the caudal third region was excised, were incubated until they reached stages 14 to 20. In embryos at stage 14, about 80% of the total PGCs were found in the capillaries of the yolk sac, whereas others were observed in the head, mainly in the mesenchyme and small vessels close to the neural tube. From stage 18 onward, many PGCs accumulated in the embryo proper; about 90% of them colonized in the head region around the neural tube. These ectopic PGCs in the head were found in the capillaries, sometimes as thrombi or emerging from them into the adjacent mesenchyme. These results show that, when the chick embryo lacked gonads, the PGCs could be concentrated in the head region and migrated from the capillaries into the mesenchyme.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092290112
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  • 8
    Electronic Resource
    Electronic Resource
    Production of germline chimeric chickens, with high transmission rate of donor-derived gametes, produced by transfer of primordial germ cells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 153-161 
    Details
    ISSN: 1040-452X
    Keywords: Chick embryo ; Germline chimerism ; Transplantation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Germline chimeric chickens were produced by transfer of primordial germ cells from White Leghorn to Barred Plymouth Rock, and vice versa. Blood was collected from stage 13-15 embryos and primordial germ cells were concentrated by Ficoll density gradient centrifugation. Approximately 200 primordial germ cells were injected into the bloodstream through the dorsal aorta of stage 14-15 recipient embryos from which blood had been drawn via the dorsal aorta prior to the injection. Intact embryos were also prepared as recipients for White Leghorns only. The manipulated embryos were cultured in recipient eggshells until hatching. Germline chimerism of the chickens reaching maturity was examined by mating them with Barred Plymouth Rocks and donor-derived offspring were identified based on their feather color. The efficiency of production of germline chimeras was 95% (19/20). When primordial germ cells were transferred from White Leghorn to Barred Plymouth Rock, the average frequency of donor-derived offspring was 81% for three male chimeras (96% for one female chimera), and it was ∼3.5 times higher for transfer in the opposite direction (23% for 6 male chimeras). Removing blood from recipient embryos prior to primordial germ cell injection enhanced the frequency of donor-derived offspring by 10% in resulting male chimeras. Male chimeras produced donor-derived offspring more frequently (∼3.8 times) than female chimeras. Increases, decreases, or no changes were observed in the frequency of donor-derived offspring from the germline chimeras with increasing age. Male to female ratio of the offspring derived from the donor primordial germ cells did not deviate significantly in male and female chimeras, suggesting that primordial germ cells that have different sex from recipient embryos could not differentiate into functional gametes. The technique for primordial germ cell transfer employed in this experiment is simple to perform and resulted in the efficient production of germline chimeras with high transmission rates of donor-derived gametes. This system provides a powerful tool for avian embryo manipulation. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080390206
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