The main purpose of this study is to extend the microscopic investigations of the pecten oculi in the quail in order to add some information on the unresolved functional anatomy of this unique avian organ. The pecten oculi of the quail was studied by scanning electron microscopy. Eighteen- to-twenty two highly vascularised accordion-like folds were joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. The structure of the double layered limiting membrane was recorded. The presence of hyalocytes with macrophage-like appearance was illustrated. It is assumed that the pecten oculi of the quail resembles that of the chicken. Illustrated morphological features of this species may add information on the active physiological role of the pecten. But still, the functional significance of this organ is a matter of controversies. 1. Introduction The pecten oculi is a unique anatomical structure of the avian eye. Three types of pecten are recognized: the conical type (pecten oculi conicus) found only in kiwis, the vaned type (pecten oculi vanellus) found in the other extant Struthioniformes, and the tinamous and the pleated type (pecten oculi plicatus) found in all other birds [1]. The pecten has been frequently studied and extensive literature about pecten is available [2, 3]. Consequently, many investigations were carried out by light and transmission electron microscopy, regarding the structure of the pecten in various avian species (Table 1). In the great majority of the studies, light and transmission electron microscopy have been used. Table 1: Research studies of pecten oculi in various avian species. The morphology of the pecten in the quail (Coturnix coturnix japonica) has been studied by scanning (SEM) and transmission (TEM) electron microscopy [4]. Moreover, branching of vessels in pecten oculi has also been investigated by light microscopy and stereomicroscopy [5]. However some morphological features such as the hyalocytes or the structure of the pectin-vitreal limiting membrane have not been recorded. The present work aims to provide some unexplored morphological data of the pecten of the quail with the use of scanning electron microscopy. In addition, a concise review and discussion aim to summarize the up to date knowledge, in order to throw light on the functional structure of this organ. 2. Material and Methods In the present study, six adult healthy quails of both sexes were used. Prior to decapitation, the animals were deeply anesthetized by inhalation of diethyl ether. The ocular
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