Loss of Tj affects the structure of the stem cell niche.

<p>(<b>A,B</b>) Adult ovaries. <i>bab-lacZ</i> highlights TFs and adjacent cap cells. (A) In a control (wt) ovary, a bundle of ovarioles is present, each with a TF at the tip, followed by a cap cell cluster (Cap), germarium (Gm) and series of follicles (Fl). (B) The rudimentary <i>tj</i><sup><i>eo2</i></sup>/<i>tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>null</sup>) mutant ovary (Ov) has irregularly distributed and abnormally long TFs, and germarium and follicles are missing. Od, oviduct; Fb, fatbody. (<b>C</b>) Comparison of the number of TF and cap cells in control (+), <i>tj</i><sup><i>39</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>hypo</sup>), and <i>tj</i><sup><i>eo2</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>null</sup>) ovarioles. (<b>D-F</b>) Niches of 2-day-old pupal ovaries. (D) In the control (wt), Tj-positive (white) cap cells are round and form a cluster at the base of the TF. TC, transition cell. (E,F) In a <i>tj</i><sup><i>z4735</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>null</sup>) ovary, cells expressing non-functional Tj protein are disc-shaped and either arranged in a single file, forming a stalk similar to the adjacent TF cells (E, F #1), or form a branched stalk (F #2). (<b>G-I</b>) Tip of an adult ovariole. Hts (red) outlines all cells, Vasa (green) marks germline cells, a yellow arrowhead marks the germarium/TF boundary, and red and blue arrows mark the posterior-and anterior-most cap cell, respectively. (G) In wild type (wt), all Tj-positive cells (white) are located inside the germarium, and the transition cell marks the boundary towards the TF. OS, ovariole sheath. (H,I) In a <i>tj</i><sup><i>39</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>hypo</sup>) ovary, a variable number of Tj-positive cells have become part of the TF (see anterior shift of the blue and red arrows). The Tj signal is weaker in the <i>tj</i><sup>hypo</sup> mutant (H,I) than in wild type (G). (<b>J</b>) Location of cap cells in <i>tj</i><sup><i>39</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>hypo</sup>) ovarioles. (<b>K,L</b>) Quantification of anterior niche cells, which include cap and TF cells, in <i>tj</i><sup><i>eo2</i></sup>/<i>tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>null</sup>) (K) and <i>tj</i><sup><i>39</i></sup><i>/tj</i><sup><i>eo2</i></sup> (<i>tj</i><sup>hypo</sup>) ovarioles (L). Graphs (C,J-L) are 'box' (25–75 percentile) and 'whisker' (maxima/minima) diagrams, showing the median (bar) and mean (plus sign). <i>n</i>, sample size; n.s., not significant (P≥0.05). Genotypic markers: <i>bab-lacZ</i> (A,B), <i>1444-lacZ/+</i> (D-F), <i>B1-lacZ</i> or <i>B1-lacZ/+</i> (C,K). Anterior is up in all images. Scale bars: 50 μm in A,B; 10 μm in D-I.</p>