Fig. 4. fos-1 function is required for uterine but dispensable for vulval expression of lin-11. (A-H) Comparison of late L3 stage lin-11::GFP(syIs80) expression in the wild type and fos-1(ar105). (A,B) In the medial plane (med) of the wild type, lin-11 expression is observed in the 2° vulval cells closest to the 1° vulval cells. (C,D) In the lateral plane (lat) of the wild type, out of the five VU intermediate precursors, lin-11 is expressed in the three cells. In the medial plane of fos-1, lin-11 is also expressed in 2° vulval cells (E,F); however, laterally, lin-11 expression is absent in the uterus (G,H). (I-R) Early to mid L4 stage expression of lin-11::GFP in the wild type and fos-1(ar105). 1° vulval cells, vulF and vulE, and 2° vulval cells, vulD, vulC, vulB2 and vulB1, are indicated. In the medial (I,J) and sub-lateral (sub-lat, K,L) planes of the wild type, terminal descendants of the 2° vulval lineage continue to express lin-11. Expression is also detected in descendants (L). In the medial (N,O) and sub-lateral (P,Q) planes of fos-1, lin-11 expression is appropriately detected in the 2° lineage. However, no uterine lin-11 expression is observed (Q). Black arrowheads point to the AC. White arrowheads point to uterine intermediate precursor cells. In A,B and E,F, brackets indicate vulval cells; elsewhere, brackets indicate cells. Dashed ovals surround uterine area where fluorescence is lost. White arrows point to GFP+ 2° vulval cell descendants. Asterisks mark expression in VC neurons. Scattered background signals are from gut autofluorescence. Scale bar: 10 µm.