Show Movies

 

These movies may be freely download. If shown, I request that I (David Shook) be credited, preferably in the slide containing the movie. I retain all copyrights and publishing rights. These movies may not be published without my consent.

These movies are quicktime movies, compressed using Photo Jpeg. Higher resolution/uncompressed versions available on request; e-mail: drs6j@virginia.edu

Please also contact me with any questions about the movies or problems downloading.

 

Powerpoint schematics of gastrluation are also available here.

 

Movie 1: Xenopus laevis; gastrulation through neurulation (5.1 MB) (description)

- HiRes version of movie 1 (46 MB)

Movie 2: Xenopus laevis; Giant Sandwich (4.5 MB) (description)

Movie 3: Xenopus laevis; Keller Sandwich (1.7 MB) (description)

Movie 4: Ambystoma mexicanum; Gastrulation (3.1 MB) (description)

Movie 5: Ambystoma mexicanum; Giant Sandwich (5 MB) (description)

Movie 6: Ambystoma maculatum; Dorsal Isolate (low mag) (8.3 MB) (description)

Movie 7: Ambystoma maculatum; Dorsal Isolate (high mag) (4.3 MB) (description)

 

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Movie Descriptions:

 

Movie 1: Xenopus laevis Vegetal View of Gastrulation & Neurulation: (15.0 hours elapsed, 48 minutes/second). View from vegetal pole, dorsal is up. Gastrulation takes about 8.5 hours, neurulation about 6.5 hours. Initally, only dorsal bottle cells are apically constricted; apical constriction (& bottle cell formation) spread laterally and then ventrally around the blastopore. Involution begins dorsally. Blastopore closure follows. Neural fold formation and closure follow. Beginning of brachial neural crest migration is apparent at end of movie. Refer to figures 1 & 2 in Gastrulation in Amphibians chapter.

Movie shows gastrulation and neurulation viewed from the vegetal pole, the future dorsal side at the top. Note the dramatic involution of the IMZ, which forms an annulus or ring of cells surrounding the large central disc of vegetal endodermal cells at the center of the vegetal pole. The bottle cells, marking the initiation of involution, have already formed mid-dorsally as indicated by the black pigment accumulation. Note that the dorsal IMZ, region above these bottle cells rolls over the blastoporal lip and disappears inside; subsequently this involution proceeds laterally, on both sides, and finally at the midventral line. As the IMZ involutes, it also extends posteriorly and converges around the circumference of the blastopore, but does so inside, out of sight. As it does so, note that the posterior neural tissue likewise converges and extends in the same fashion, on the outside; together these convergent extension movements squeeze the blastopore shut and simultaneously elongate the anterior-posterior axis of the embryo, pushing the future tail away from the head. Note that the converging and extending neural plate simultaneously rolls up to form a neural tube. See Keller, 1975,1976; Keller et al., 1991.

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Movie 2: Xenopus laevis Giant Sandwich: (7 hours, 40 minutes elapsed, 45 minutes/second); Vegetal is down, animal up, dorsal at the midline, ventral at the lateral edges. Movie shows gastrulation in two dimensions; two embryos have been cut down the ventral side, the most animal and vegetal tissue removed, along with any involuted tissue and place deep side to deep side, such that the entire surface of the explant is covered by an epithelium. The line of darkly pigmented cells are bottle cells forming around what would have been the blastopore. Convergence and extension occur as in intact embryos, but no involution occurs.

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Movie 3: Xenopus laevis Keller Sandwich: (9 hours elapsed, 45 minutes/second): Vegetal is down, animal is up; explant starts at about stage 10. Refer to figure 3 in Gastrulation in Amphibians chapter.

"Sandwich" explants were made of the "dorsal lip" tissue, immediately above the initial blastopore shown in the preceding movie, consisting of both the endodermal/mesodermal and neural tissue. These regions of two embryos are cut out with eyebrow hair knives and sandwiched with their inner, deep surfaces together; these explants here were made of the dorsal 120 degree sector of the gastrula; larger explants consisting of the entire 360 degrees can also be made (giant explants). The mesodermal/endodermal regions and posterior neural regions converge, extend, and differentiate into notochord and somitic mesoderm and posterior neural tissue, respectively. The explant will do these movements when cultured on agarose, unattached to the substrate. In fact, adhesion to the substrate retards these movements.

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Movie 4: Ambystoma mexicanum Vegetal Gastrulation: (18.7 hours elapsed, 72 minutes/second ) View from vegetal pole, dorsal is up.

A timelapse recording of the vegetal region of the Ambystoma gastrula shows formation of the bottle cells and initial invagination and the subsequent involution of the involuting marginal zone. Ingression of the superficial cells of the involuting marginal zone occurs at its vegetal edge in the blastoporal groove, but is best seen in movies of explants (Movies 5-7)

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Movie 5: Ambystoma mexicanum Giant Sandwich (24 hours elapsed time; 8 fps; 80 minutes/second) Vegetal edge is down, dorsal is at vertical center, ventral is at either side. Movie begins at about stage 10+. The animal portion of the explant expands (epiboly) while the vegetal edge contracts. As the dorsal midline begins to extend, the dorsal blastoporal bottle cells un-constrict and apical constriction lateral of the endodermal field begins; subduction under the endodermal mounds follows, as does further dorsal extension and vegetal edge contraction. Loose cells leaving the surface of the explant at the end of the movie are artifactual. Refer to figure 12 in Gastrulation in Amphibians chapter.

Ambystoma Giant showing ingression and con ext of noto A giant explant of the early Ambystoma gastrula shows convergence and extension of the notochordal region (bottom center of the explant extends toward bottom of the frame), and ingression of superficial cells at the posterior end of this extending axis.

Figure S2 from Shook et al. 2002

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Movie 6: Ambystoma maculatum Blastoporal Subduction, Low Resolution: (9.5 hours elapsed, 60 minutes/sec) Movie starts about stage 12.5. View looking at the roof of the gastrocoel, anterior to the left, blastopore is on the right, dorsal is horizontal center. Cells are rolling around the blastopore from outside to in, apically constricting and subducting. Refer to figure 11 in Gastrulation in Amphibians chapter.

Figure S4 from Shook et al. 2002

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Movie 7: Ambystoma maculatum Subduction, High Resolution: (5:15 hours elapsed, 30 minutes/second) Movie starts about stage 12.5. Region of subduction at blastopore; anterior right, dorsal down; out of focus cells at upper left are endoderm, in focus cells are presumptive mesoderm. Mesodermal cells constrict their apices (to a greater or lesser degree), then subduct under the endoderm

A high magnification timelapse movie shows apical constriction of the presumptive somitic mesodermal cells on the surface of the involuting marginal zone (small cells at lower right) and their subsequent subduction beneath the surface of the vegetal endoderm (large cells at the upper left). Refer to figure 12 in Gastrulation in Amphibians chapter.

 

 

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Powerpoint slides:

 

Schematic sequence for gastrulation (by Ray Keller)