Bemis W E, Grande L
Department of Zoology, University of Massachusetts, Amherst, Massachusetts 01003.
Department of Geology, Field Museum of Natural History, Chicago, Illinois 60605.
J Morphol. 1992 Jul;213(1):47-83. doi: 10.1002/jmor.1052130106.
A large sample of embryological material of the North American paddlefish Polyodon spathula (Acipenseriformes: Polyodontidae) confirms that early development in Polyodon is very similar to that reported for the sister group of Polyodontidae, the sturgeons (Acipenseridae). Polyodon illustrates many basic aspects of acipenseriform (and actinopterygian) head development that have not been adequately described. In this paper, we provide an overview of external features of cranial development using scanning electron microscopy. The observations are correlated with staging schemes previously proposed for paddlefishes and other acipenseriforms. Events that occur after the start of neurulation (stage 19) to the start of feeding (stage 46) are emphasized. New information on the structure and folding of the mandibular and hyoid segments permits an understanding of the early development of the pharyngeal region. In addition, we offer new descriptions of the hatching gland, the olfactory organ, the sensory barbel, and the initiation of paddle outgrowth. We also comment on the mode of origin of the hypophysis, and refute the notion that it is derived from the lips of the anterior neuropore as suggested in older literature. This information sets the stage for future comparative and experimental studies of the embryology of basal actinopterygians. © 1992 Wiley-Liss, Inc.
对北美匙吻鲟（Polyodon spathula，鲟形目：匙吻鲟科）大量胚胎学材料的研究证实，匙吻鲟的早期发育与匙吻鲟科的姐妹类群鲟科（Acipenseridae）所报道的情况非常相似。匙吻鲟展示了许多尚未得到充分描述的鲟形目（及辐鳍鱼纲）头部发育的基本方面。在本文中，我们利用扫描电子显微镜对颅骨发育的外部特征进行了概述。这些观察结果与先前为匙吻鲟和其他鲟形目动物提出的分期方案相关。重点强调了从神经胚形成开始（第19阶段）到开始摄食（第46阶段）之间发生的事件。关于下颌和舌骨节段的结构及折叠的新信息有助于理解咽区的早期发育。此外，我们提供了关于孵化腺、嗅觉器官、感觉触须以及桨状突起起始的新描述。我们还对垂体的起源方式进行了评论，并驳斥了旧文献中提出的垂体源自前神经孔唇部的观点。这些信息为未来对基干辐鳍鱼胚胎学的比较和实验研究奠定了基础。© 1992威利 - 利斯公司。
