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[Show abstract][Hide abstract] ABSTRACT: The structure of the conus papillaris in an Australian lizard, the bobtail goanna (Tiliqua rugosa) was investigated by light and electron microscopy. In this strongly diurnal species, the conus papillaris consists of a heavily vascularized and pigmented, finger-like structure about 1 mm in diameter and 3-4 mm in length. It is situated over the optic nerve head and projects into the vitreous chamber. Within the conus are numerous capillaries and larger blood vessels, melanocytes and occasional mast cells. Many of the capillaries display prominent luminal and abluminal microfolds. Other capillaries show no microfolds while still others display an intermediate number of microfolds. The larger blood vessels are usually indistinguishable as to being either arterioles or venules. The endothelial cells of all blood vessels show a population of cytoplasmic granules. The melanocytes are large pleomorphic cells usually rich in microfilaments. Unmyelinated nerve processes are plentiful within the conus and the Schwann cells enclosing these nerve fibres are occasionally seen to be pigmented. The morphology of the conus papillaris indicates a heavy involvement in the transport of materials. It is considered to be homologous to the pecten oculi of the avian eye; to the falciform process of the teleost eye; to the supraretinal vessels of amphibians and to the intraretinal vessels of the mammalian eye.
Preview · Article · Aug 1989 · Histology and histopathology
[Show abstract][Hide abstract] ABSTRACT: The pecten oculi of the great blue heron (Ardea herodias) has been examined by both light and electron microscopy. In this species the pecten is large and of the pleated type. It consists of 14-15 acordion folds that are joined apically by a more heavily pigmented bridge of tissue which holds the pecten in a fan-like shape widest at its base. As in other species it is situated over the optic nerve head and projects out into the vitreous. Within each fold are numerous capillaries, larger supply and drainage vessels and many melanocytes. The capillaries are extremely specialized vessels which display extensive microfolds on both their luminal and abluminal borders. The endothelial cell bodies are extremely thin with most organelles present in a paranuclear location. The capillaries are surrounded by thick fibrillar basal laminae which are felt to be structurally useful. Pericytes are a common feature of these capillaries. The numerous pleomorphic melanocytes which form an incomplete sheath around the capillaries and other blood vessels are also felt to be important in structural support of the pecten. The morphology of the pecten of the great blue heron is indicative of a heavy involvement in the transport of materials.
Preview · Article · Aug 1991 · Histology and histopathology
[Show abstract][Hide abstract] ABSTRACT: The pecten oculi of the barred owl (Strix varia) has been examined by light and transmission electron microscopy. The pecten in this species is of the pleated type and is small in comparison to the size of the ocular globe. The pecten consists of 8-10 accordion-like folds that are linked apically by a pigmented tissue bridge. Each fold contains numerous capillaries, larger supply and drainage vessels, and abundant pleomorphic melanocytes. Most of these capillaries are extremely specialized vessels that possess plentiful microfolds on both the luminal and abluminal surfaces. Some capillaries however display only a few microfolds. The endothelial cell bodies are extremely attenuated, with most organelles located near the nucleus. All capillaries are surrounded by a very thick fibrillar basal lamina, which is thought to provide structural support to these small vessels. Pericytes are commonly found within these thickened basal laminae. Numerous melanocytes are also present, with processes that form an incomplete sheath around the capillaries. These processes are also presumed to provide structural support for the capillaries. As in other avian species, the morphology of the barred owl pecten is indicative of extensive involvement in substance transport. When compared to the pecten of more visually-oriented species, this pecten is smaller, has fewer folds, and displays a reduced number of microfolds within the capillaries. In these and other features, the barred owl pecten is similar to the pecten of the great horned owl (Bubo virginianus).
No preview · Article · Feb 1996 · Histology and histopathology