Morphogenesis of the different types of photoreceptors of the chicken (Gallus domesticus) retina and the effect of amblyopia in neonatal chicken
| Autor: | Maria Sen Mun Wai, Dietrich E. Lorke, Lai Sin Kung, David T. Yew |
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| Rok vydání: | 2006 |
| Předmět: |
Histology
Time Factors genetic structures Morphogenesis Chick Embryo Biology Amblyopia Retina chemistry.chemical_compound Retinal Rod Photoreceptor Cells medicine Animals Cilia Instrumentation Mitosis Ocular Physiological Phenomena Microvilli Cilium Embryo Retinal Anatomy Rod Cell Outer Segment Microvillus eye diseases Medical Laboratory Technology medicine.anatomical_structure chemistry Microscopy Electron Scanning Retinal Cone Photoreceptor Cells sense organs Chickens Photoreceptor inner segment |
| Zdroj: | Microscopy research and technique. 69(2) |
| ISSN: | 1059-910X |
| Popis: | Despite the great variety in chicken photoreceptors, existing morphogenetic studies only deal with two types: rods and cones. We have therefore examined by scanning electron microscopy the first appearance and maturation of different retinal photoreceptors in 36 chicken embryos (Gallus domesticus), aged 5-19 days prehatching. On day 5 of incubation, chicken retinae were only composed of proliferating ventricular cells devoid of photoreceptors. On day 8, outer mitotic cells were separated from inner differentiating photoreceptors, by the transient layer of Chievitz. Ball-like protrusions appeared at the ventricular surface, representing the first signs of photoreceptor inner segment formation. From day 10 onward, double cones, single cones, and rods could be clearly distinguished, and occasional cilia were detected at their tip. On day 12, inner segments had increased in length and diameter, and frequently carried a cilium representing the beginning of outer segment formation. On day 14, most photoreceptors displayed a distinct outer segment. On day 19, photoreceptors had essentially assumed adult morphology. Based on the shape of their outer segments, two subtypes of cones and three subtypes of double cones could be distinguished. Throughout development, we observed microvilli close to maturing photoreceptors, either originating from their lateral sides, from their tip, or from Muller cells. Microvillus density peaked between day 12 and 14, indicating an important role in photoreceptor morphogenesis. Unilateral occlusion of the eyes of posthatching chicken reduced the proportion of double cones to single cones in the retina, indicating dependence of retinal morphogenesis upon functional activity of visual cells. |
| Databáze: | OpenAIRE |
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