Spitzenkörper (SPK) |
present |
1 |
|
Vesicles concentrated in thin layer beneath apical plasma membrane and/or loosely organized throughout apical dome |
absent |
0 |
|
SPK function |
SPK not nucleating microtubules |
1 |
|
SPK structure (light microscopy) |
central core absent or not visible |
1 |
|
SPK detailed structure (electron microscopy) |
central core enriched with microvesicles |
2 |
|
Ribosome cluster distal to SPK or vesicle accumulation in apical dome |
absent or not observed |
0 |
|
Macrovesicles with uniformly dense lumen |
present, 70–120 nm diam. |
1 |
|
Microvesicles (25–45 nm diam.) with uniformly dense lumen |
present (polyhedral profile) |
2 |
|
Macrovesicles (90–250 nm diam.) with an electron dense core, and less dense periphery |
absent |
0 |
|
Microvesicles with an electron dense core, and less dense periphery (30-65 nm diam.) |
absent |
0 |
|
Filasomes (protein-coated microvesicles; 30–40 nm diam.) |
present and common |
2 |
|
Sub-apical cluster of putative lipid globules |
absent |
0 |
|