ATLAS OF THE MOUSE BRAIN AND SPINAL CORD

Abstract

(1980). 24. Granule cell densities were measured from three separate areas from midlinc sections of two mutant, one wild-typc, and one hetcrozyous 129/Sv mice by counting cells in a 25,000-[bm sample. A mean of 156 ± 22 cells per 25,000 [m2 was recorded for the six mutant samples and 147-28 for the combined heterozygous and wild-type samples. We have observed no evidence for differences betwecn wild-type and heterozygous mice and therefore have pooled data here. The data for midline length and cell number of the Purkinje layer used to calculate Purkinic cell density were obtained from the same sections with the addition of one outbred mutant and one wild-type 129/Sv mouse. The sample size in all cases was too small for statistical analysis and reflects the small number of mice currently available on the 129/Sv inbred background. All effects described , both in overall size and cerebellar pattern-ing, have also been observed in an equivalent number of outbred mice examined. Nature 332,604 (1988); A. Martinez-Arias, N. E. Baker, P. W. Ingham, Development 103, 157 (1988). 32. The en-conserved domains are based on sequences of the human, mouse, and chicken En-1 and En-2 genes (C. Logan, S. Noble-Topham, M. Hanks, A. Joyner, unpublished results) and the Xenopus En-2 gene (A. Hemmati-Brivanlou, J. de la Torre, C. Holt, R. Harland, Development, in press) and Drosophila en and iv (6, 7). Outside of the conserved domains, only the human and mouse En-1 or En-2 genes show homology. 33. Brains were dissected from 2-month-old En-2^"/ Etn2hd, En-22d/+, and +1+ mice on the 129/Sv background, which had been perfused with 4%