Figure 1

a: Percentage of hydrocephalus in LEW/Jms rats by litter number (parity) and total percentage (All). There was a significant increase in percentage of affected rats between the 1^st and 2^nd and the 1^st and 3^rd litters, P < 0.001. This was not maintained for the 4^th and 5^th litters. The number of litters in the data sets is depicted above the columns.b: The ratio of males to females in the parental LEW/Jms strain and in the BC₁ progeny. In the parental strain, there were significantly more males than females with hydrocephalus (black bars, P < 0.001), and also among the total pups born (striped bars). In the B group [(F × L) × L], there was a significant excess of females among the non-hydrocephalic pups, (open bars, P < 0.001 and a significant excess of males in the hydrocephalic pups, P < 0.001. In the C group [L × (L × F)], there were no significant departures from the expected 1:1 sex ratios for the hydrocephalic or the non-hydrocephalic rats (ns).c: Percentage of hydrocephalus in [(F × L) × L] BC₁ rats by litter number (parity) and in total. There was a significant increase in the percentage expressing hydrocephalus between the 1^st and 2^nd litters, P < 0.001. This was not maintained in subsequent litters. The number of litters in the data sets is depicted above the columns. d: Percentage of hydrocephalus in [L × (L × F)] BC₁ rats by litter number (parity) and in total. There was a steady and significant increase in expression between 1^st litters and all subsequent litters, P < 0.001. The number of litters in the data sets is depicted above the columns.