Figure 3
From: Distal spinal nerve development and divergence of avian groups
Sclerotome polarity differences between chicken, dove, and emu. (A,B), chicken. (A) Peanut agglutinin (PNA) staining at E7, showing poorly defined sclerotome polarity in the pygostyle region. (B) PNA staining at E10 (HH36). At this stage, PNA staining is diffuse in the pygostyle region, but preferentially stains intervertebral disc domains in the free vertebrae region of the tail. (C) Rock dove, PNA staining at HH36 stage. Like chicken, the rock dove (a neoave) exhibits poorly defined PNA staining in the pygostyle region. (D) Emu, PNA staining at HH36 stage. Unlike chicken and rock dove, emu PNA staining at this stage stains sclerotome and neural arches, with no perceptible staining differences between the pygostyle and free vertebrae tail regions. Also unlike chicken and rock dove, intervertebral discs are unstained. White bars indicate extent of pygostyle region. (E) Chicken pygostyle region, 8 days post-hatching (D8), sagittal view of distal tail, Alcian blue/picrosirius red staining. Intervertebral discs are fully formed between all pygostyle-specific vertebrae. Abbreviations: A: anterior, D: dorsal, IVD: intervertebral disc, P: posterior, V: ventral.
