Sanyal S, Jansen H G, de Grip W J, Nevo E, de Jong W W
Department of Anatomy, Erasmus University, Rotterdam, The Netherlands.
Invest Ophthalmol Vis Sci. 1990 Jul;31(7):1398-404.
The rudimentary eyes of the mole rat (Spalax ehrenbergi) are located under the skin and do not respond to light stimuli. However, removal of the eyes disturbs photoperiod perception in these animals. To help clarify the possibly remaining function of the eyes in this species, the authors studied their development and ultrastructure. In the early embryos the presumptive eye regions--the epithelium, lens vesicle, and optic cup--appear initially normal. As development progresses, the iris-ciliary body complex originates prematurely from the margin of the optic cup and shows a very rapid and massive growth. This pigment-laden tissue mass remains attached to the corneal stroma, obliterates the anterior chamber, and prevents the formation of the corneal endothelium and Descemet's membrane. In the developing lens the elongation of the lens fibers leads to the formation of a rudimentary lens nucleus that becomes disorganized and vacuolated and eventually also becomes vascularized. The optic fissure fails to close, the eyes remain colobomatous, and the optic disc appears atrophic. In contrast, retinal histogenesis progresses relatively normally, resulting in structurally reduced but well-differentiated photoreceptor, neuronal, and ganglion cell layers in the adult eye. Immunohistochemically, the presence of opsin could be demonstrated in the photoreceptor cells. The latter features may indicate that these rudimentary eyes are still functioning in the complex neuroendocrine pathways mediating photoperiodicity.
瞎鼹鼠（Spalax ehrenbergi）的原始眼睛位于皮肤之下，对光刺激无反应。然而，摘除眼睛会扰乱这些动物的光周期感知。为了帮助阐明该物种眼睛可能剩余的功能，作者研究了其发育和超微结构。在早期胚胎中，假定的眼区——上皮、晶状体泡和视杯——最初看起来正常。随着发育的进行，虹膜 - 睫状体复合体过早地从视杯边缘起源，并呈现出非常快速且大量的生长。这个充满色素的组织块附着于角膜基质，闭塞前房，并阻止角膜内皮和Descemet膜的形成。在发育中的晶状体中，晶状体纤维的伸长导致形成一个原始的晶状体核，该核变得紊乱、空泡化，最终也发生血管化。视裂未能闭合，眼睛仍有脉络膜缺损，视盘出现萎缩。相比之下，视网膜组织发生相对正常进行，导致成年眼睛中结构上有所减少但分化良好的光感受器、神经元和神经节细胞层。免疫组织化学显示，视蛋白存在于光感受器细胞中。后者的特征可能表明这些原始眼睛仍在介导光周期的复杂神经内分泌途径中发挥作用。
