Fig. 1.

The flathead mutation preferentially affects the brain. A, The bodies of unaffected (left) and flathead(right) littermates on P10 are similar in size. Also note the slightly flattened curvature of the flatheadskull (arrow). B, A graph of body weights of flathead (striped bars) and unaffected rats (black bars) reveals no significant difference in body weights from E19 until the end of the first postnatal week. C, A flathead brain (right) is significantly smaller than an unaffected (left) littermate on P14. Note that although the entire brain is smaller, the cortex and cerebellum are especially reduced in size. D, A graph of brain weights from E19 to P7 shows that a flathead brain weighs approximately one-half that of a normal brain. Four to eight animals were used for each point. *p < 0.05.