Soma position | Basal (no contract with ventricle) | Apical–basal (contact with ventricle) | Apical (contact with ventricle) |
Processes | Tangential | Radial (electrondense) | Radial (light) |
Nuclei | Round–spindle | Oval–irregular | Round–oval |
Chromatin | Lax (clumps) | Lax (occasionally condensed) | Small aggregates |
Nucleoli | 1–2 (large) | 1–2 (large) | 1–2 (small) |
Cytoplasm | Scant | Dark | Light (basal)–dark (apical) |
Smooth endoplasmic reticulum | + | +++ | + |
Annulate lamellae | No | Yes | No |
Golgi apparatus | Small | Large (thin saccules) | Small (swollen saccules) |
Vesicles closely associated with Golgi | ++ | ++++ | + |
Free ribosomes | ++++ | ++ | ++ |
Mitochondria | + | +++ (round–small) | +++ (large–elongated) |
Centriole | Close to nuclei, away from ventricle | Most apical cytoplasm | None detected |
Cilium | Internalized (8+0), away from ventricle | One–specialized (8+0), contact with ventricle | Many (9+2), contact with ventricle |
Ciliary rootlets | No | No | Yes |
Microtubules | ++++ | ++ | + |
Intermediate filaments | − | ++ | +++ |
Junctional complex | Small zonulae adherens | Small desmosomes | Large junctional complex |
Interdigitation | −− | + | ++ |