Mouse <i>Wnt</i> genes exhibit discrete domains of expression in the early embryonic CNS and limb buds

TLDR

"Seven Wnt genes show restricted brain expression, with Wnt‑3, Wnt‑3a, and Wnt‑7b forming sharp forebrain boundaries; in the spinal cord, Wnt‑1, Wnt‑3, and Wnt‑3a are dorsal, Wnt‑5a, Wnt‑7a, and Wnt‑7b ventral, and Wnt‑4 is both dorsal and floor‑plate; in forelimb primordia, Wnt‑3, Wnt‑4, Wnt‑6, and Wnt‑7b are uniformly expressed, while Wnt‑5a shows a proximal‑to‑distal gradient and ventral ectoderm expression, and Wnt‑7a is dorsal ectoderm." That's long but one sentence. Need to keep concise but include key patterns. Maybe split? But must be one sentence.

Abstract

ABSTRACT Mutation and expression studies have implicated the Wnt gene family in early developmental decision making in vertebrates and flies. In a detailed comparative analysis, we have used in situ hybridization of 8.0- to 9.5-day mouse embryos to characterize expression of all ten published Wnt genes in the central nervous system (CNS) and limb buds. Seven of the family members show restricted expression patterns in the brain. At least three genes (Wnt-3, Wnt-3a, and Wnt-7b) exhibit sharp bound-aries of expression in the forebrain that may predict sub-divisions of the region later in development. In the spinal cord, Wnt-1, Wnt-3, and Wnt-3a are expressed dorsally, Wnt-5a, Wnt-7a, and Wnt-7b more ventrally, and Wnt-4 both dorsally and in the floor plate. In the forelimb primordia, Wnt-3, Wnt-4, Wnt-6 and Wnt-7b are expressed fairly uniformly throughout the limb ectoderm. Wnt-5a RNA is distributed in a proximal to distal gradient through the limb mesenchyme and ectoderm. Along the limb’s dorsal-ventral axis, Wnt-5a is expressed in the ventral ectoderm and Wnt-7a in the dorsal ectoderm. We discuss the significance of these patterns of restricted and partially overlapping domains of expression with respect to the putative function of Wnt signalling in early CNS and limb development.