Ultrastructure studies on Retina and Cornea of Octopus macropus from Egyptian Mediterranean Coasts

Document Type : Original Article

Author

Zoology Department, Faculty of Science, Ain Shams University, Cairo, Egypt.

Abstract

Adult animals of Octopus macropus were collected alive from
Abu Quir coasts, Alexandria, Egypt. They were transported to the
laboratory at Faculty of Science, Ain Shams University and dissected to
obtain their eyes and put in suitable fixative. After that, the routine
ultrastructure techniques were applied for examination of the retina and
cornea by the transmission electron microscope. The results revealed that
the retina is formed of two layers; the visual cells and the connective
tissue. The visual cells contain a small amount of a granular endoplasmic
reticulum, rounded mitochondria and oval nuclei with distinct nucleoli.
From each four different visual cells, four rhabdomeres united to form a
prismatic rhabdome. Examination with higher magnification power
showed presence of groups of 8 to 9 lamellated structures that form dense
membranes with different lengths. These lamellated structures are similar
to the myelin membranes and present in all cells but not connected to the
plasma membrane. The cornea is made of three layers; the outer epithelial
layer of hexagonal cells that have small mitochondria and oval nuclei.
The median thick layer of fibrous connective tissue and the inner
endothelium layer of cuboidal cells having small mitochondria and large
rounded nuclei.

Keywords

Egyptian Journal of Aquatic Biology and Fisheries
Volume 22, Issue 2
April 2018
Pages 163-171

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