Browsing by Author "Stricker, Stephen A."

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    Tetracycline Labeling Studies of Calcification in Nemertean Worms
    (Blackwell Publishing, 1985) Cavey, Michael J.; Stricker, Stephen A.; Cloney, Richard A.; Biological Sciences; Faculty of Science; University of Calgary
    Calcification of the stylet apparatus in nemertean worms was investigated by fluorescence microscopy following incubation of living specimens in sea water solutions of tetracycline. the synthesis of nail-shaped stylets that contain calcium phosphate, and the composition of the granular basis that anchors the central stylet tot he worm's pro-boscis, wer examined in five species of nemerteans belonging to the order Hoplonemertea. After a two-week treatment with either tetracycline-HCI or chlortetracycline, the basis appeared intensely fluorescent in all specimens. Such observations, coupled with results from electron microprobe analyses, indicate that the basis is calcified. None of the developing stylets, however, exhibited fluorescence after incubation in tetracycline. Hypotheses acounting for the lack of tetracycline labeling by stylets are discussed.
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    Ultrastructure of transrectal coelomoducts in the sea cucumber Parastichopus californicus (Echinodermata, Holothuroida)
    (Springer-Verlag, 1990) Cavey, Michael J.; Shinn, George L.; Stricker, Stephen A.; Biological Sciences; Faculty of Science; University of Calgary
    The perivisceral coelom of the sea cucumber Parastichopus californicus is connected to the lumen of the hindgut by as many as 200 short transrectal ducts. Each duct is lined by a pseudostratified epithelium composed of: (i) monociliated, tonofilament-containing cells, (ii) myoepithelial cells, (iii) bundles of neurites, and (iv) granule-containing cells. In most places the lumen of each duct is lined by the monociliated, tonofilament-containing cells. The myoepithelial cells are predominantly basal in position and circular in orientation, but some border the lumen and parallel the long axis of the duct. The epithelium of a duct consists of the same types of cells as occur in the peritoneum covering the rectum and differs markedly from the nonciliated, cuticularized epithelium that lines the lumen of the rectum. Based on ultrastructural characteristics, the transrectal ducts represent evaginations of the peritoneum overlying the rectum and are thus "coelomoducts" sensu Goodrich. The possibility is discussed that perivisceral coelomoducts of holothuroids function in regulating coelomic volumes.