Expression of alpha-skeletal actin in mouse and chicken embryos. Results of the in situ hybridization on embryos of mouse, stage E10.5 (A) en stage E11.5 (B). Details of the atrium are shown for the early stage embryo (E) and the later stage embryos (F). The same experiment has been conducted on chicken embryos of stage HH20 (C) and HH25 (D). Again details of the atrium are shown for both stages (G, H). Structures with staining are labeled: atrium (a) branchial arches (ba), diencephalon (di), distal progress zone (dpz), fore limb bud (flb), heart (h), hind limb bud (hlb), hyoid arch (hy), lens (ls), liver (lv), mandible (m), mandibular arch (md), maxillary arch (mx), mesencephalon (ms), metencephalon (met), myelencephalon (mye), nasal pituitary (np), otic vesicle (ov), somite (som), telencephalon (tel), ventricle (v).