Summary
The holothurian testes (as well as ovary) consists of three layers arranged concentrically around a central lumen which contains developing germ cells. The outer coelomic layer measuring 6 μ in thickness contains ciliated squamous epithelial cells, smooth muscle processes, nerve tracts, and occasional pigment cells. Interior to the outer layer is a haemal sinus measuring about 3 μ and consisting of haemal fluid composed of collagenous fibers and electron dense particles. Coelomocytes are embedded in this extracellular fluid matrix. The inner germinal layer, measuring 9 μ at the thickest regions consists of germinal cells, squamous epithelial cells, and coelomocytes. Occasional coelomocytes within the haemal sinus and germinal layer of the testicular wall contain spermatids enclosed within cytoplasmic vacuoles, suggesting phagocytosis as one of their cellular functions.
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This investigation was supported by a National Research Council grant to F. S. Chia.
The author would like to thank Dr. Bruce J. Crawford for his invaluable advice and technical assistance, Dr. F. S. Chia for critically reading the manuscript, and Mr. Bill Adams for preparation of Figure 11.
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Atwood, D.G. Ultrastructure of the gonadal wall of the sea cucumber, Leptosynapta clarki (echinodermata: holothuroidea). Z.Zellforsch 141, 319–330 (1973). https://doi.org/10.1007/BF00307409
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DOI: https://doi.org/10.1007/BF00307409