Fig. 2. Taste buds form normally in exogastrulae and endomesodermal isolates of exogastrulae. (A) A transverse section through the endomesodermal region of an intact exogastrula has been immunostained for calretinin to reveal the distribution of differentiated taste buds, which are present in large number. The arrow indicates the apical region of the taste bud shown at higher magnification in B. (C) This CR-IR taste bud found in an intact exogastrula displays the characteristic accumulation of CR-IR material in the apical microvilli (*), which is commonly seen in vivo (Barlow et al., 1996). (D) Numerous CR-IR taste buds were found in this endomesodermal isolate from a stage 11.5 exogastrula. The arrowhead indicates the apical region of the taste bud shown in E at higher magnification. (E) Again, this taste bud has intense CR-IR in the apical microvilli, throughout the cytoplasm of numerous fusiform cells within the bud. (F) Another CR-IR taste bud from an endomesodermal isolate, illustrating cytoplasmic immunostaining within fusiform cells, as is the case in vivo. Scale bars: 150 µm in A; 100 µm in B,D; are 25 µm in C,E,F.