ULTRASTRUCTURE OF COELOMIC EPITHELIUM AND COELOMOCYTES OF INTACT AND WOUNDED STARFISH ASTERIAS RUBENS L.
A. N. Gorshkov,1 M. I. Blinova, G. P. Pinaev
Institute of Cytology RAS, St. Petersburg;
1 e-mail: angorsh@yahoo.com
Samples of coelomic epithelium and coelomocytes suspension of intact and wounded starfishes Asterias rubens
L. were analyzed by electron microcopy. It has been demonstrated that coelomic epithelium is composed
of three types of cells: flagellar (approx. 60 %), secretory (approx. 3 %) and myoepithelial (approx. 37 %). Flagellar
and secretory cells form the apical surface of coelomic epithelium. Secretory cells are represented by two
subtypes: granular and mucous secretory cells. Myoepithelial cells are located in the basal zone of the epithelium.
Adjacent flagellar cells are separated by intercellular gaps of various size in 4—5 % of cases. These gaps
are apparently the lacunae left by the flagellar cells after their departure to the coelomic cavity. The morphological
pattern of transition of coelomic epithelium flagellar cells to the coelomocytes has been characterized. No
significant structural alterations in organization of the coelomic epithelium were revealed after moderate wounding
used in the present study. Small round-shaped young coelomycytes (approx. 3 %) and bigger mature coelomocytes
(approx. 97 %) were found in coelomocytes suspension. A flagellum was revealed on the surface of one
of the young coelomocytes. Surface of the mature coelomocytes forms the processes of various size and structure;
their cytoplasm contains lysosomes and fagocytic vacuoles of different size. After wounding, activation of
coelomocytes was noted finding expression in the sharp rise in the number and the length of their surface filopodia,
and in the multicellular aggregates formation. By the sum of the ultrastructural data, histogenesis of coelomocytes
from the flagellar cells of the coelomic epithelium is supposed to be a process of cellular transdifferentiation.
Key words: Asterias rubens, coelomic epithelium, coelomocytes, regeneration
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