Time‐lapse tracing of mitotic cell divisions in the early Xenopus embryo using microscopic MRI

Abstract

Mitotic cell division is a highly regulated cellular event in all organisms, but its direct visualization in the vertebrates is limited to animals with transparent embryos. Here, we report on the use of microscopic magnetic resonance imaging (mMRI) to noninvasively observe mitotic cell division of early blastomeres in the optically opaque Xenopus laevis embryo. Due to intrinsic tissue contrast, cell nuclei can be directly visualized without the need for contrast enhancing labeling. By taking two-dimensional in vivo time-lapse image sequences, the karyokinesis of a blastomere is followed. Timing and orientation of the cleavages can be traced for five cell divisions to establish a cell lineage tree, including orientation and timing of the mitosis. This work demonstrates for the first time the use of MRI for the visualization of cell divisions and expands the experimental scope of the Xenopus embryo. Developmental Dynamics 235:3059 -3062, 2006.

A uniplanar three-axis gradient set for in vivo magnetic resonance microscopy

“…The development of a compact uniplanar gradient set with good thermal insulation and heat dissipation was originally motivated by time-lapse imaging of models of early vertebrate development, specifically externally developing amphibian embryos [6] or cultured mouse embryos [16]. The uniplanar design allows the gradient and RF coil hardware to be placed extremely close (less than 5 mm and 1 mm, respectively) to the sample with a corresponding increase in signal detection sensitivity and gradient current efficiency.…”

“…There is increasing interest in high-resolution MRM of millimeter scale samples such as developing embryos [5][6][7][8][9][10] and for non-invasive histology of entire organisms, organs or tissue samples [11][12][13][14].…”

Two‐dimensional and three‐dimensional time‐lapse microscopic magnetic resonance imaging of Xenopus gastrulation movements using intrinsic tissue‐specific contrast

“…Previously conducted MRI of frog embryos made use of extrinsic contrast to follow tissue movements during blastula and gastrula stages (Jacobs and Fraser, 1994) and intrinsic tissue contrast for tracing cell lineages of early blastomeres (Papan et al, 2006). Here, we show that intrinsic tissue contrast in the MR images correlates with the histological structure of the early embryo and can be used for studying tissue morphogenesis during blastula and gastrula stages.…”

“…A home-built 3-mm solenoidal RF coil (Papan et al, 2006) wrapped around a hollow glass tube into which the sample tube was inserted was used for all data collection. For 3D imaging, we used a T1-weighted spin-echo pulse sequence with TR/TE ϭ 400 msec/8 msec and two averages yielding an imaging time of 55 min.…”

Spatiotemporal lipid profiling during early embryo development of Xenopus laevis using dynamic ToF-SIMS imaging

“…Considering that DAG can be rapidly phosphorylated to phosphatidic acid (GPA ), which is a critical step in phospholipid biosynthesis ( 39,40 ), it is speculated that in the center of the fusion site phospholipase-mediated hydrolysis of SM and phosphatidylinositol 4,5-bisphosphate occurs to generate possible DAG ( 41 ), which quickly builds associated dynamic processes that the visualization of the mitosis directly in the developing embryo is of great interest. However, only the species featuring a transparent embryo that develops extracorporeally (e.g., teleosts) can be observed noninvasively by optical microscopy ( 44 ). With regard to amphibian embryos with almost complete optical opacity, such as the X. laevis embryo, observations are restricted.…”