Photomicrograhps of Apoamphisiella vernalis from Minas Gerais, after protargol-impregnation, to show variations in morphogenesis pattern of ventral ciliature.

(A) Proter and (B) opisthe of middle divider with two ventral cirral rows (arrows) producing one extra anlage between each anlagen V and VI (arrowheads); arrows point to parental ventral rows. (C–E) Specimen with three ventral cirral rows (arrows) at different focal planes. Arrowhead in C points to right marginal cirral row; arrowhead in D shows early development of undulating membranes anlage of opisthe; arrowhead in E points to anlage formation within rightmost ventral row of opisthe. OA = oral anlage; anlagen labeled with roman numbers, where “o” names the opisthe and “p” names the proter.