Robertson G N, McGee C A S, Dumbarton T C, Croll R P, Smith F M
Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, B3H 1X5 Canada.
J Morphol. 2007 Nov;268(11):967-85. doi: 10.1002/jmor.10558.
Many teleosts including zebrafish, Danio rerio, actively regulate buoyancy with a gas-filled swimbladder, the volume of which is controlled by autonomic reflexes acting on vascular, muscular, and secretory effectors. In this study, we investigated the morphological development of the zebrafish swimbladder together with its effectors and innervation. The swimbladder first formed as a single chamber, which inflated at 1-3 days posthatching (dph), 3.5-4 mm body length. Lateral nerves were already present as demonstrated by the antibody zn-12, and blood vessels had formed in parallel on the cranial aspect to supply blood to anastomotic capillary loops as demonstrated by Tie-2 antibody staining. Neuropeptide Y-(NPY-) like immunoreactive (LIR) fibers appeared early in the single-chambered stage, and vasoactive intestinal polypeptide (VIP)-LIR fibers and cell bodies developed by 10 dph (5 mm). By 18 dph (6 mm), the anterior chamber formed by evagination from the cranial end of the original chamber; both chambers then enlarged with the ductus communicans forming a constriction between them. The parallel blood vessels developed into an arteriovenous rete on the cranial aspect of the posterior chamber and this region was innervated by zn-12-reactive fibers. Tyrosine hydroxylase- (TH-), NPY-, and VIP-LIR fibers also innervated this area and the lateral posterior chamber. Innervation of the early anterior chamber was also demonstrated by VIP-LIR fibers. By 25-30 dph (8-9 mm), a band of smooth muscle formed in the lateral wall of the posterior chamber. Although gas in the swimbladder increased buoyancy of young larvae just after first inflation, our results suggest that active control of the swimbladder may not occur until after the formation of the two chambers and subsequent development and maturation of vasculature, musculature and innervation of these structures at about 28-30 dph.
包括斑马鱼（Danio rerio）在内的许多硬骨鱼都通过充满气体的鳔来主动调节浮力，鳔的体积由作用于血管、肌肉和分泌效应器的自主反射控制。在本研究中，我们研究了斑马鱼鳔及其效应器和神经支配的形态发育。鳔最初形成一个单腔室，在孵化后1 - 3天（dph），体长3.5 - 4毫米时充气。如zn - 12抗体所示，侧神经已经存在，并且通过Tie - 2抗体染色表明，在颅侧已经形成了平行的血管，为吻合毛细血管环供血。神经肽Y -（NPY -）样免疫反应性（LIR）纤维在单腔室阶段早期出现，血管活性肠肽（VIP）- LIR纤维和细胞体在10 dph（5毫米）时发育。到18 dph（6毫米）时，前腔室从原始腔室的颅端外翻形成；然后两个腔室都扩大，连通管在它们之间形成一个缩窄。平行的血管在后腔室的颅侧发育成动静脉网，该区域由zn - 12反应性纤维支配。酪氨酸羟化酶 -（TH -）、NPY -和VIP - LIR纤维也支配该区域和侧后腔室。VIP - LIR纤维也证实了早期前腔室的神经支配。到25 - 30 dph（8 - 9毫米）时,后腔室侧壁形成了一条平滑肌带。尽管鳔中的气体在首次充气后立即增加了幼体的浮力，但我们的结果表明，直到两个腔室形成以及这些结构的脉管系统、肌肉组织和神经支配在大约28 - 30 dph随后发育和成熟之后，鳔的主动控制才可能发生。
