Microvascular architecture of the rat choroid: Corrosion cast study

Abstract

This study presents the details of the microvasculature of the rat choroid visualized by scanning electron microscopy of vascular corrosion casts. Wistar Kyoto rats were anesthetized with intraperitoneal sodium pentobarbital. The vascular system was perfused with heparinized saline, and Mercox resin was injected into the cannulated carotid arteries. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, washed with water, and freeze dried. The casts were examined with a Hitachi S-2360N scanning electron microscope (SEM). Corrosion casts of the entire choroidal vasculature revealed that the two long posterior ciliary arteries supplied the entire uveal vasculature. In the posterior choroid, these arteries formed five to seven branches on each side supplying the adjacent choriocapillaris. No interarterial or arteriovenous anastomoses were seen. The choriocapillaris appeared as a nonhomogeneous and nonlobular monolayer capillary network, consisting of dense honeycomb and irregular patterns. There are two distinct venous systems in the rat choroid. The venous blood from the central region, peripapillary choroid, and sometimes the optic nerve head drain into the posterior ciliary vein. The venous blood from the iris, ciliary body, anterior choroid, and half of the posterior choroid drain into the vortex veins. Corrosion casts and the SEM have shown details of the choroidal vascular architecture. These three-dimensional observations indicate that the rat choroidal vasculature has different features from those of humans and other primates. Despite these interspecies differences, the establishment of a thorough baseline concept of choroidal vasculature should permit additional studies of the choroidal pathology and enable the proper interpretation of results from rat experimental models for extrapolation to humans. Anat Rec 264: [63][64][65][66][67][68][69][70][71] 2001.

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

“…2(f) and 3(f) are caused by major choroidal vessels. 22,23 To demonstrate further the complementary nature of these three modalities, a PAOM B-scan, 1D FA-SLO profile, and SD-OCT B-scan are compared in Fig. 4.…”

The effect of topical anti-muscarinic agents on subfoveal choroidal thickness in healthy adults

“…The present study showed that although tropicamide had no significant effect on ChT, Eye cyclopentolate caused significant rapid choroidal thickening in healthy adults. Although the choroid is structurally constituted by the branches of ciliary arteries, 13 it also includes non-vascular smooth muscle cells, and a network of spindle-shaped or star-shaped cells. 1,14 These cells are considered to have a role in changing the ChT in proportion to the effects of local mediators and sympathetic and parasympathetic systems.…”

Microvascular Architecture of the Rabbit Eye: A Scanning Electron Microscopic Study of Vascular Corrosion Casts

“…The iris, the cilia and the entire choroid of the rabbit are drained only by the vortex veins. In contrast, the rat eye has two drainage pathways; the posterior choroid is drained by the posterior ciliary vein, and the anterior segment of the eyeball is drained by the vortex veins [2,13]. Rats have been used exclusively in the past in order to study the elevation in intraocular pressure triggered by the cauterization of vortex veins.…”

“…The general distribution of the major vessels in the rabbit eyeball has already been outlined [5,11,12,20]. Scanning electron microscopy (SEM) has been used to study corrosion casts, and comparative descriptions of the rabbit's ocular vasculature have been published [2,5,8,11,12]. These studies indicated marked interspecies variation in vasculature among mammalian eyes.…”