Table 1

Comparison of inversion in V. globator and V. carteri.

Characteristic

V. carteri

V. globator


Type of inversion

A

B


Duration of inversion

Approximately 45 min [20,22]

Approximately 50 min


Sequence of processes

The phialopore opens;

the anterior hemisphere inverts;

the posterior hemisphere contracts;

the posterior hemisphere inverts;

the phialopore closes [20,22,26]

The posterior hemisphere contracts;

the posterior hemisphere inverts;

the phialopore opens;

the anterior hemisphere inverts;

the phialopore closes

[25,36,37]


Site of the initiation of inversion

Point-shaped initiation site at the anterior pole of the spheroid [22]

Ring-shaped initiation site at the equator of the spheroid


Direction of cell shape changes

From the anterior pole to the posterior pole [22]

Initially, from the equator to the posterior pole; then, from the equator to the anterior pole


Diameter of embryo

Immediately before inversion: approximately 65 μm [22]

immediately after inversion: approximately 60 μm [22]

Immediately before inversion: approximately 80 μm

Immediately after inversion: approximately 60 μm


Relative size (volume) of the cells of the embryo during inversion

Reproductive cells are roughly 100 to 200 times larger than somatic cells [22]

Reproductive cells are roughly one to five times larger than somatic cells


Cell shape immediately before inversion

All cells are spindle shaped [20,22]

All cells are teardrop shaped


Cell shape in bend region during inversion

Flask-shaped cells

(radially symmetrical at the chloroplast ends) [20,22,24]

Paddle-shaped cells (wedge shaped at the chloroplast ends)


Cell shape of cells that have passed the bend region

Column-shaped cells [20,22]

Pencil-shaped cells (the column shape does not appear until inversion is completed)


Order of cell shape changes

All cells undergo the same consecutive cell shape changes: spindle → flask → column [20,22,24]

Posterior and anterior hemispheres invert with different cell shapes changes;

cells in the posterior hemisphere: teardrop → spindle → paddle (except for the cells close to the posterior pole) → pencil → column;

cells in the anterior hemisphere: teardrop → disc → pencil → column


Shape of nuclei throughout inversion

Minor changes [20]

Major changes


Cytoplasmic bridges

Only between cells of the embryo [20,22,24,29]

Between cells of the embryo and between embryonic and parent cells


Phialopore

Swastika-shaped opening; four lips of the cell monolayer curl outward and backward [20,22]

Circular opening; while the opening widens, the cells and cytoplasmic bridges around the phialopore become passively stretched


Denting

Only before inversion [20,26,39]

Before and after inversion


Flagella

Only flagellar stubs approximately 2 μm in length that do not grow during inversion; flagella grow asymmetrically after inversion [76]

Flagella grow symmetrically throughout inversion


Höhn and Hallmann BMC Biology 2011 9:89   doi:10.1186/1741-7007-9-89

Open Data