Burns M S, Bellhorn R W, Impellizzeri C W, Aguirre G D, Laties A M
Department of Ophthalmology, School of Medicine, University of California, Davis 95616.
Curr Eye Res. 1988 Feb;7(2):103-14. doi: 10.3109/02713688808995739.
Laboratory beagle dogs with an apparent absence of a tapetum lucidum were identified by ophthalmoscopic examination. Breeding experiments demonstrated a probable autosomal recessive mutation. Studies of the development of the tapetal abnormality showed that up to postnatal day 21 the tapetum was normal by light and ultrastructural morphology. Subsequent to that time the tapetal rodlets failed to accumulate electron-dense material, did not accumulate zinc, and degenerated primarily into spherical inclusion bodies of varying electron density. In the early phases of the degeneration the rough endoplasmic reticulum formed large whorls of membrane denuded of ribosomes. With time, the inclusions became electron lucent, and the entire tapetal cell degenerated, ending with almost total loss of the tapetum lucidum by approximately one to two years of age. The structure of the retina was normal. Retinal function measured by electroretinography was normal except for a slight elevation of dark adapted white light thresholds. It is speculated that the hereditary defect may be defective synthesis of the tapetal rodlet matrix or of the zinc-complexing substance of the tapetum.
通过检眼镜检查确定了明显缺乏明毯的实验比格犬。繁殖实验表明这可能是一种常染色体隐性突变。对明毯异常发育的研究表明，直到出生后第21天，明毯在光学和超微结构形态上都是正常的。在那之后，明毯小棒未能积累电子致密物质，没有积累锌，并且主要退化为具有不同电子密度的球形包涵体。在退化的早期阶段，粗面内质网形成了大量没有核糖体的膜漩涡。随着时间的推移，包涵体变得电子透明，整个明毯细胞退化，到大约一到两岁时明毯几乎完全消失。视网膜结构正常。除了暗适应白光阈值略有升高外，通过视网膜电图测量的视网膜功能正常。据推测，遗传缺陷可能是明毯小棒基质或明毯锌络合物质的合成缺陷。
