Jensen Abbie M
Biology Department, 221 Morrill South, University of Massachusetts, Amherst, MA 01003, USA.
Dev Dyn. 2005 Feb;232(2):385-92. doi: 10.1002/dvdy.20224.
The embryonic optic cup generates four types of tissue: neural retina, pigmented epithelium, ciliary epithelium, and iris smooth muscle. Remarkably little attention has focused on the development of the iris smooth muscle since Lewis ([1903] J. Am. Anat. 2:405-416) described its origins from the anterior rim of the optic cup neuroepithelium. As an initial step toward understanding iris smooth muscle development, I first determined the spatial and temporal pattern of the development of the iris smooth muscle in the chick by using the HNK1 antibody, which labels developing iris smooth muscle. HNK1 labeling shows that iris smooth muscle development is correlated in time and space with the development of the ciliary epithelial folds. Second, because neural crest is the only other neural tissue that has been shown to generate smooth muscle (Le Lievre and Le Douarin [1975] J. Embryo. Exp. Morphol. 34:125-154), I sought to determine whether iris smooth muscle development shares similarities with neural crest development. Two members of the BMP superfamily, BMP4 and BMP7, which may regulate neural crest development, are highly expressed by cells at the site of iris smooth muscle generation. Third, because humans and mice that are heterozygous for Pax6 mutations have no irides (Hill et al. [1991] Nature 354:522-525; Hanson et al. [1994] Nat. Genet. 6:168-173), I determined the expression of Pax6. I also examined the expression of Pax3 in the developing anterior optic cup. The developing iris smooth muscle coexpresses Pax6 and Pax3. I suggest that some of the eye defects caused by mutations in Pax6, BMP4, and BMP7 may be due to abnormal iris smooth muscle.
神经视网膜、色素上皮、睫状上皮和虹膜平滑肌。自刘易斯（[1903]《美国解剖学杂志》2:405 - 416）描述虹膜平滑肌起源于视杯神经上皮的前缘以来，对其发育的关注少之又少。作为理解虹膜平滑肌发育的第一步，我首先通过使用标记发育中的虹膜平滑肌的HNK1抗体，确定了鸡胚中虹膜平滑肌发育的时空模式。HNK1标记显示，虹膜平滑肌的发育在时间和空间上与睫状上皮褶皱的发育相关。其次，由于神经嵴是已被证明能产生平滑肌的唯一其他神经组织（勒利夫尔和勒杜林[1975]《胚胎学与实验形态学杂志》34:125 - 154），我试图确定虹膜平滑肌发育是否与神经嵴发育有相似之处。BMP超家族的两个成员BMP4和BMP7可能调节神经嵴发育，它们在虹膜平滑肌产生部位的细胞中高度表达。第三，由于携带Pax6突变的杂合子人类和小鼠没有虹膜（希尔等人[1991]《自然》354:522 - 525；汉森等人[1994]《自然遗传学》6:168 - 173），我确定了Pax6的表达。我还检测了发育中的视杯前部Pax3的表达。发育中的虹膜平滑肌共表达Pax6和Pax3。我认为，Pax6、BMP4和BMP7突变导致的一些眼部缺陷可能是由于虹膜平滑肌异常所致。
