A correlative scanning and transmission electron microscope study of the pecten oculi of Japanese quail

Abstract

A correlative morphological study of the pecten oculi of Japanese quail was performed by scanning (SEM) and transmission (TEM) electron microscopy. A three-dimensional profile was obtained by preparing solid resin corrosion casts. SEM examination revealed its trapezoidal shape and a laminar surface that is thrown into 18 vertical pleats. A surface view of the tips of pleats and transverse sections demonstrated a close continuity between all pectineal folds. The folded vascular membrane is arranged such that the base of each fold is attached to the retina, while the other end is embedded in a bridge, the whole organ protruding into vitreous body. The vascular supply to the pecten pursues a slightly tortuous course along its attached border and a complete system of vascular branches was demonstrated; terminal arterioles form a dense capillary network. The pectineal laminae consist predominantly of modified blood capillaries and interstitial pigment cells. Both basal and luminal surfaces of the endothelial cells are covered with microfolds which are tall, erect, and compact luminally and, in contrast, short and irregularly oriented basally. The intervascular tissue contains pigment cells and moderately sized intercellular spaces. The pigment cells are polymorphic with vesicular nuclei, abundant mitochondria, and numerous melanin granules.