Table 1. Stages of oral development in... | Rockefeller University Press

Table 1.

Stages of oral development in Tetrahymena (after Lansing et al. [1985]; Nelsen [1981])

Stage	nOA	Old OA
1a	Strings of BBs form off of several somatic BBs in the right postoral row
1b	New BBs populate the space between the two postoral rows and have random orientations in regard the cell’s AP axis
2	BBs undergo duplication and become pairs composed of an older ciliated posterior BB and a younger unciliated anterior BB
3	The BB pairs associate side-by-side to form M rows. M1 and M2 become visible
4a	The most posterior M3 emerges. In all M rows, the anterior BBs undergo ciliation, starting from the row’s right end and progressing toward the left UM merges as a file of single BBs that move away from the rest of the oral field toward the right margin of the OP. At the posterior end of the OP, there is a large group of mostly unciliated, newly formed BBs. This area is already present in stage 2 and is likely the site of continuing proliferation of BBs, which are subsequently added to the forming rows
4b	A third most anterior subrow of BBs starts to form at each M row’s right end and progresses to the left. The formation of the third subrow is most advanced in M1 and least advanced in M3 The UM fully separates from the rest of the oral field except for the most posterior area containing young unciliated BBs to which all 4 row ends connect to
5a	The assembly of the third most anterior subrow has completed in all M rows. The ciliation of the third subrow continues right to left. The M rows condense by reduction of spaces between the BB columns and became less curved. In M1, two new BBs form a limited fourth subrow. A single triplet of BBs is resorbed at the right end of each M row The UM is now composed of a single row, while the posterior field of new BBs is small and located near the posterior end of the UM	Initiation of limited remodeling of the old OA. The ribbed wall microtubules disassemble. The outer UM row moves slightly to the cell’s right side, and a new outer row starts to form at the anterior end of the UM
5b	In the M rows, several BBs that were previously ciliated, loose cilia. Especially prominent deciliation occurs at the left end of M3, where it affects two terminal BB triplets The outer row starts to form in the UM	The old outer row of UM starts to be resorbed. The new UM outer row is completed, and its BBs undergo ciliation
5c–d	Resorption of specific BB on the left side of M rows, including the two leftmost BBs in the most anterior subrow of M1 and a total of 7 BBs at the left end of M3 The new UM has two full-length rows, and the outer row is fully ciliated. In contrast, cilia in the inner UM row resorb. The ribbed wall microtubules start to grow out of the inner UM row	In the old UM, the degradation of the outer row is complete, and the new outer row is completely ciliated. The ribbed wall microtubules grow out of the inner UM row
5f	The M rows undergo sculpturing of their right ends that involves displacements of specific BBs resulting in the dissolution of their triplet columns. The sculpturing of M3 is most extensive, and the BB columns are no longer apparent The ribbed wall is fully developed	The ribbed wall assembly is completed

Stage	nOA	Old OA
1a	Strings of BBs form off of several somatic BBs in the right postoral row
1b	New BBs populate the space between the two postoral rows and have random orientations in regard the cell’s AP axis
2	BBs undergo duplication and become pairs composed of an older ciliated posterior BB and a younger unciliated anterior BB
3	The BB pairs associate side-by-side to form M rows. M1 and M2 become visible
4a	The most posterior M3 emerges. In all M rows, the anterior BBs undergo ciliation, starting from the row’s right end and progressing toward the leftUM merges as a file of single BBs that move away from the rest of the oral field toward the right margin of the OP. At the posterior end of the OP, there is a large group of mostly unciliated, newly formed BBs. This area is already present in stage 2 and is likely the site of continuing proliferation of BBs, which are subsequently added to the forming rows
4b	A third most anterior subrow of BBs starts to form at each M row’s right end and progresses to the left. The formation of the third subrow is most advanced in M1 and least advanced in M3The UM fully separates from the rest of the oral field except for the most posterior area containing young unciliated BBs to which all 4 row ends connect to
5a	The assembly of the third most anterior subrow has completed in all M rows. The ciliation of the third subrow continues right to left. The M rows condense by reduction of spaces between the BB columns and became less curved. In M1, two new BBs form a limited fourth subrow. A single triplet of BBs is resorbed at the right end of each M rowThe UM is now composed of a single row, while the posterior field of new BBs is small and located near the posterior end of the UM	Initiation of limited remodeling of the old OA. The ribbed wall microtubules disassemble. The outer UM row moves slightly to the cell’s right side, and a new outer row starts to form at the anterior end of the UM
5b	In the M rows, several BBs that were previously ciliated, loose cilia. Especially prominent deciliation occurs at the left end of M3, where it affects two terminal BB tripletsThe outer row starts to form in the UM	The old outer row of UM starts to be resorbed. The new UM outer row is completed, and its BBs undergo ciliation
5c–d	Resorption of specific BB on the left side of M rows, including the two leftmost BBs in the most anterior subrow of M1 and a total of 7 BBs at the left end of M3The new UM has two full-length rows, and the outer row is fully ciliated. In contrast, cilia in the inner UM row resorb. The ribbed wall microtubules start to grow out of the inner UM row	In the old UM, the degradation of the outer row is complete, and the new outer row is completely ciliated. The ribbed wall microtubules grow out of the inner UM row
5f	The M rows undergo sculpturing of their right ends that involves displacements of specific BBs resulting in the dissolution of their triplet columns. The sculpturing of M3 is most extensive, and the BB columns are no longer apparentThe ribbed wall is fully developed	The ribbed wall assembly is completed