Fig. 4. CUP expression. (A) CUP expression in a young seedling is restricted to a band of cells between the vegetative apex and the young leaves (arrows). (B) A longitudinal section through the inflorescence apex shows CUP expression separating the developing bracts from the centre of the SAM. (C) A late stage 3 flower (Carpenter et al., 1995) shows CUP expression between the sepal primordia and the centre of the floral meristem. (D) By stage 5, CUP expression can be seen between the emerging primordia in all whorls. (E) In longitudinal sections within whorls, CUP expression can also be observed between organs, in this case between two stamen primordia in a stage 5 flower. (F) At later stages of flower development a strong line of CUP expression is observed in the connective of the anthers. Expression is also observed at the tip of developing carpels in whorl 4. (G) CUP expression is observed between emerging ovule primordia and in the ovule primordia themselves. (H) More mature ovules show CUP expression in a ring surrounding the nucellus at the point of integument attachment. An enlargement of one ovule (inset) shows the ring of CUP expression. Numbers indicate floral whorls. se, sepal; br, bract; pl, placenta; cw, carpel wall; n, nucellus; i, integument. Scale bars: 100 µm.