Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
Dev Biol. 2019 Apr 15;448(2):309-319. doi: 10.1016/j.ydbio.2018.10.013. Epub 2018 Oct 25.
The extracorporeal vasculature of the colonial ascidian Botryllus schlosseri plays a key role in several biological processes: transporting blood, angiogenesis, regeneration, self-nonself recognition, and parabiosis. The vasculature also interconnects all individuals in a colony and is composed of a single layer of ectodermally-derived cells. These cells form a tube with the basal lamina facing the lumen, and the apical side facing an extracellular matrix that consists of cellulose and other proteins, known as the tunic. Vascular tissue is transparent and can cover several square centimeters, which is much larger than any single individual within the colony. It forms a network that ramifies and expands to the perimeter of each colony and terminates into oval-shaped protrusions known as ampullae. Botryllus individuals replace themselves through a weekly budding cycle, and vasculature is added to ensure the interconnection of each new individual, thus there is continuous angiogenesis occurring naturally. The vascular tissue itself is highly regenerative; surgical removal of the ampullae and peripheral vasculature triggers regrowth within 24-48 h, which includes forming new ampullae. When two individuals, whether in the wild or in the lab, come into close contact and their ampullae touch, they can either undergo parabiosis through anastomosing vessels, or reject vascular fusion. The vasculature is easily manipulated by direct means such as microinjections, microsurgeries, and pharmacological reagents. Its transparent nature allows for in vivo analysis by bright field and fluorescence microscopy. Here we review the techniques and approaches developed to study the different biological processes that involve the extracorporeal vasculature.
群体海鞘 Botryllus schlosseri 的体外脉管系统在几个生物学过程中起着关键作用：运输血液、血管生成、再生、自我非自我识别和共生。脉管系统还将群体中的所有个体相互连接，由单层外胚层衍生细胞组成。这些细胞形成一个带有基底层朝向管腔、顶端朝向由纤维素和其他蛋白质组成的细胞外基质的管，称为被囊。血管组织是透明的，可以覆盖几平方厘米，比群体中的任何单个个体都要大得多。它形成一个分支并扩展到每个群体边缘的网络，并终止于称为壶腹的椭圆形突起。Botryllus 个体通过每周的芽生周期进行自我替换，并且增加脉管系统以确保每个新个体的相互连接，从而自然发生持续的血管生成。血管组织本身具有很强的再生能力；对壶腹和周围脉管系统进行手术切除会在 24-48 小时内引发再生，包括形成新的壶腹。当两个个体，无论是在野外还是在实验室中，紧密接触并且它们的壶腹接触时，它们可以通过吻合血管进行共生，或者拒绝血管融合。脉管系统可以通过直接手段（如微注射、显微手术和药理学试剂）进行轻松操作。其透明性质允许通过明场和荧光显微镜进行体内分析。在这里，我们回顾了研究涉及体外脉管系统的不同生物学过程的技术和方法。
