Figure 9.

Slowed-down respiratory-like rhythm and lack of response to a low pH challenge in Tshz3^lacZ/lacZ embryos. A, Photomicrograph of a whole hindbrain preparation obtained from an E16.5 embryo, with the positioning of the recording electrode. Shown are integrated phrenic nerve discharges (Int C4) at pH 7.4 (top trace) and pH 7.2 (bottom trace) for a WT embryo. B, Same legend as in A for a Tshz3^lacZ/lacZ embryo. C, Quantification of burst frequencies for WT and Tshz3^lacZ/lacZ embryos at pH 7.4 (white bars) and pH 7.2 (black bars) at E16.5 (left) and E18.5 (right). The asterisks indicate significantly different values (p < 0.05). Numbers of hindbrain preparations analyzed are indicated on the bars. The motor output of the respiratory network recorded from C4 nerve roots is significantly lower in the mutants and does not respond to low pH at either E16.5 or E18.5. r, Rostral; c, caudal.