. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RETINOIC ACID DEFECTS IN FUNDULUS EMBRYOS 289 Table II Analysis of relinoic acid effects on cartilage fonnation in the head and pectoral girdle Concentration of retinoic acid Ongin Skeletal element Ahv' 5 X 10 ' M 10-" A/ 10-' M lO-'M Neural" Crest Mandibular Arch Hyoid Arch Branchial Arches Neurocranium Non-Neural" Crest Pectoral Girdle Quadrate (q) Pterygoid (p) Meckel's (mc) Hyosymplectic (hs) Basihyal (bh) Ceratohyals (ch) Epibranchials â Pharyngobranchials â Basibranchials Hypohranchials Ceratobranchials
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RETINOIC ACID DEFECTS IN FUNDULUS EMBRYOS 289 Table II Analysis of relinoic acid effects on cartilage fonnation in the head and pectoral girdle Concentration of retinoic acid Ongin Skeletal element Ahv' 5 X 10 ' M 10-" A/ 10-' M lO-'M Neural" Crest Mandibular Arch Hyoid Arch Branchial Arches Neurocranium Non-Neural" Crest Pectoral Girdle Quadrate (q) Pterygoid (p) Meckel's (mc) Hyosymplectic (hs) Basihyal (bh) Ceratohyals (ch) Epibranchials â Pharyngobranchials â Basibranchials Hypohranchials Ceratobranchials Ethmoid plate (ep) Lamina orbitonasahs (lo) Trabeculae (t) Epiphyseal bar (eb) Anterior orbital (ao) Posterior orbital (po) Polar cartilage (pi) Hypophyseal plate (hp) Auditory capsule (ac) Parachordals (pc) Coracoscapulae (cs) Proximal radials (pr) P P M P P P M/A M/A - , ^^^^ M M M M. p -^â jj^^l p A ;>^|||^^^^^H M ('')^^^^^^^H ^^^^^1 ' Abbreviations used in Figure 4. ^ Based on Langille and Hall. 1988; Schilling and Kimmel. 1997. Key: P = Present and normal; M = Malformed; i^ = Reduced m number; Absent; Q = Duplicated; | = Unidentified cartilage. absent (not shown). Most larvae of embryos exposed to 10"' M RA lack pharyngeal cartilage, but 94% of these larvae possess multiple fins with two or more pairs of coracoscapulae and proximal radials (Fig. 4L, and Van- dersea et ai, in press). Table II lists the cartilaginous skeletal elements that are present in control larvae and in larvae that were ex- posed, as gastrulating embryos, to increasing concentra- tions of RA. To aid in the analysis of RA-induced defects, skeletal elements have been grouped according to their embryological origin and their position within the neuro- cranium or the pharyngeal skeleton. The presence (P) or absence (A) of individual elements is noted, as well as whether the cartilages are malformed (M) or reduced in number (RN). Duplications (D) and unidentified cartilage (?) are also indicated.
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