Fig. 4.

En is expressed in the abdominal appendage and abdominal epidermis. a En expression at 48 h APF is between the bristle cells (arrowhead) as well as in the posterior margin of the fourth segment. The boundary between the fourth and fifth abdominal segment is marked with a line. b At 72 h the appendage-specific expression is apparent in the posterior region of the appendage (arrowhead). c En (blue) is expressed in a posterior region of each abdominal segment (data not shown). The gray box delineates the region of the abdomen shown in a, b, and d. The red line indicates the location of the transverse cross-section in d. d Transverse cross-section of the appendage at 72 h shows that there are two independent regions of expression: one in the abdominal epidermis (ae) and one in the appendage (app). En expression defines the anterior–posterior axis of the appendage e a cartoon summary of En expression in the abdominal appendage