Drysdale T A, Crawford M J
Department of Zoology, University of Toronto, Ontario, Canada.
Dev Biol. 1994 Apr;162(2):394-401. doi: 10.1006/dbio.1994.1096.
In order to more accurately determine the mechanism by which retinoic acid causes embryonic defects, we have developed a simple method of locally applying retinoic acid rather than immersing the whole embryo in retinoic acid solutions. Retinoic acid was suspended in corn oil and then injected between the surface and the deep ectodermal layers of an early gastrula Xenopus embryo. When droplets containing retinoic acid were injected into the presumptive head region, the embryos exhibited inhibited development of anterior structures near the injection site. Development of the eye, cement gland, hatching gland, olfactory pits, and expression of engrailed protein were all disrupted near the injection site. Inhibited development of anterior structures was far greater on the injected side of the embryo than on the uninjected side. The retinoic acid droplet did not cause an anterior shift of structures on the injected side relative to the uninjected side. These experiments suggest that retinoic acid does not cause global respecification of axial level in the head, but rather suppresses development of anterior structures. Retinoic acid injected into presumptive trunk regions had no discernible effect.
为了更准确地确定视黄酸导致胚胎缺陷的机制，我们开发了一种局部应用视黄酸的简单方法，而不是将整个胚胎浸入视黄酸溶液中。视黄酸悬浮于玉米油中，然后注射到早期原肠胚非洲爪蟾胚胎的表面和深层外胚层之间。当将含有视黄酸的液滴注射到预定头部区域时，胚胎在注射部位附近表现出前部结构发育受抑制。在注射部位附近，眼睛、黏液腺、孵化腺、嗅窝的发育以及engrailed蛋白的表达均受到破坏。胚胎注射侧前部结构的发育抑制远比未注射侧严重得多。视黄酸液滴并未导致注射侧结构相对于未注射侧向前移位。这些实验表明，视黄酸不会引起头部轴向水平的整体重新指定，而是抑制前部结构的发育。注射到预定躯干区域的视黄酸没有明显作用。
