Alluchon-Gérard M J
Arch Anat Microsc Morphol Exp. 1982;71(1):51-70.
In embryos and very young dogfish made hypothyroidian by various treatments (radiothyroidectomy, surgical thyroidectomy and PTU treatment), ultrastructural abnormalities have been observed in all tested cartilages : Meckel's, branchial and pelvic cartilages. Many chondrocytes show a dark nucleus, enlarged REG vesicles and very electron dense hyaloplasm giving the cell a very peculiar reticulated aspect. Other chondrocytes appear unaffected. Cartilage ultrastructure is almost fully restored after a 21 days' recovery time. Around abnormal chondrocytes, extracellular matrix components are scarce. Moreover, matrix mineralization occurs around some abnormal chondrocytes by hydroxyapatite crystalization, never seen in normal embryos. During recovery, these crystals are preserved. When the antithyroid effects of PTU are compensated for by a simultaneous thyroxine treatment, cartilage abnormalities are minimized. If radiothyroidectomy is performed on young embryos, chondrocyte differentiation is delayed. It is concluded from these various experiments that thyroid hormones are required for the normal differentiation of cartilage and for the maintenance of its integrity in this fish.
在通过各种处理（放射性甲状腺切除术、手术甲状腺切除术和丙硫氧嘧啶治疗）导致甲状腺功能减退的胚胎和非常年幼的角鲨中，在所有测试的软骨（梅克尔软骨、鳃软骨和骨盆软骨）中都观察到了超微结构异常。许多软骨细胞显示细胞核深色、内质网泡增大且透明质质非常电子致密，使细胞呈现出非常奇特的网状外观。其他软骨细胞似乎未受影响。经过21天的恢复时间后，软骨超微结构几乎完全恢复。在异常软骨细胞周围，细胞外基质成分稀少。此外，在一些异常软骨细胞周围通过羟基磷灰石结晶发生基质矿化，这在正常胚胎中从未见过。在恢复过程中，这些晶体得以保留。当通过同时进行甲状腺素治疗来补偿丙硫氧嘧啶的抗甲状腺作用时，软骨异常会减至最小。如果对幼胚进行放射性甲状腺切除术，软骨细胞分化会延迟。从这些各种实验得出的结论是，甲状腺激素对于这种鱼类软骨的正常分化及其完整性的维持是必需的。
