Morse D E, McCann P S
Invest Ophthalmol Vis Sci. 1984 Aug;25(8):899-907.
A more accurate description of the changes that occur in the neuroectodermal portion of the developing eye is possible if the surface ectoderm and its underlying mesectoderm are dissected away prior to scanning electron microscopic analysis. A clean preparation of the basal surface of the neuroectoderm with its basal lamina can be prepared by this method. The primitive eyes form during day 11 as lateral diverticula from the forebrain in the rat embryo. These optic vesicles initially have a broad attachment to the diencephalon. By day 12, a true optic stalk connects the optic vesicle to the brain. As the vesicle approaches the surface ectoderm, it involutes to form the optic cup. During day 13, the cup deepens and creates a prominent rim on all but its ventral side. This cleft in the ventral portion of the optic cup is known as the optic fissure. Three portions of the neuroectodermal eye are apparent at this stage: the optic cup, optic stalk, and a short narrow region that joins these two--the collum. The optic fissure extends into the collum but ends abruptly at the junction of the collum with the stalk. The fissure closes on day 14. Its only remnants at this time are a shallow groove in the optic cup and a small patent portion in the collum that permits passage of the intraocular vessels.
如果在扫描电子显微镜分析之前将表面外胚层及其下方的中胚层分离，就可以更准确地描述发育中的眼睛神经外胚层部分所发生的变化。通过这种方法，可以制备出带有基膜的神经外胚层基底表面的纯净标本。原始眼睛在大鼠胚胎第11天形成，是前脑的侧憩室。这些视泡最初与间脑有广泛的连接。到第12天，一条真正的视柄将视泡与大脑相连。当视泡靠近表面外胚层时，它内卷形成视杯。在第13天，视杯加深，除腹侧外，其余各侧都形成一个明显的边缘。视杯腹侧的这个裂隙称为视裂。在这个阶段，神经外胚层眼睛的三个部分很明显：视杯、视柄以及连接这两者的一个短而窄的区域——颈部。视裂延伸到颈部，但在颈部与视柄的交界处突然终止。裂隙在第14天闭合。此时它唯一的残余部分是视杯中的一条浅沟和颈部一个允许眼内血管通过的小的开放部分。
