Fig. 3. Defect in lens development caused by lens lineage-specific ablation of Sip1 gene. (A-F) Comparison of normal (A-C) and Sip1-defective (D-F) lenses. (B,E) After E11.5 Sip1-defective lens remains attached to surface ectoderm through persistent stalk (arrowhead). (C,F) In situ hybridization of E11.5 lens specimens analogous to (B,E) for Sip1 transcripts. Normal lens shows Sip1 expression throughout the lens vesicle (C), while the Sip1-defective vesicle shows no Sip1 transcripts in the stalk and anterior half of the vesicle, and residual low-level Sip1 transcripts in the posterior half (F). (G,I) Hematoxylin and Eosin (H-E) staining of E14.5 lenses. Normal lens shows full development of mature lens fiber cells (G), while Sip1-defective lens is still attached to the cornea through the stalk (arrowhead), and shows no development of mature lens fiber cells (I). (H,J) H-E staining of P0 lenses. Sip1-defective lens still attached to the cornea (arrowhead) as a small cell mass. (K) Homozygous dyl (Foxe3-defective) mouse lens at P0, showing morphological resemblance to Sip1-defective lens in J. (L) Distribution of apoptotic cells in the normal and Sip1-defective lens vesicles at E10.5, E11.5 and E12.5, where TUNEL-positive nuclei (yellow) among DAPI-stained nuclei (blue) are shown. Scale bars: 100 µm. (M) Statistics of apoptosis measured in meridian lens sections in their anterior and posterior halves. The fraction of TUNEL-positive nuclei in DAPI-stained nuclei is shown using data of two (E12.5) to six (other stages) lens specimens. Net increment of TUNEL+ apoptotic cell population under the Sip1-defective condition is indicated by hatched graph bars. le, lens epithelium; lf, mature lens fibers; cor, cornea; el, eyelid. Scale bars: 100 µm.