Record Details
The fine structure of the arthrobranch of the crayfish, Pacifastacus leniusculus Dana, with special reference to active ion uptake
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | The fine structure of the arthrobranch of the crayfish, Pacifastacus leniusculus Dana, with special reference to active ion uptake |
| Names |
Morse, Howard Curtis
(creator) Harris, Patricia J. (advisor) Dornfeld, Ernst J. (advisor) |
| Date Issued | 1967-01-27 (iso8601) |
| Note | Graduation date: 1967 |
| Abstract | The gills of an Oregon crayfish, Pacifastacus leniusculus Dana, were examined with histological and histochemical techniques and their fine structure was investigated by electron microscopy. Special attention was given to the structural basis of active ion uptake. The histology of these gills was the same as that of other crayfish species described by earlier workers. There are basically three cell types: hypodermal cells of stalk and tubules, connective tissue cells, and nephrocytes. In addition two cell products are present: the cuticle and connective tissue fibers. The hypodermal cells of the stalk combine into a solid sheet underlying the cuticle while those of the tubules are pear-shaped with a body, neck, and cytoplasmic sheet. The body, containing the nucleus, continues into a smaller neck which flares out into the flattened sheet running perpendicular to the length of the neck but parallel to and closely apposed to the cuticle. Nephrocytes are large, multinucleate phagocytes attached to the walls of efferent vessels of the stalk and tubules as well as the stalk mantle canal. These cells are found to contain much acid phosphatase activity. Electron microscopy reveals that the nephrocytes are covered on the surface with a system of long microvilli which drape over cis-ternae. The plasma membrane delimits the inner surface of the cis-ternae on which numerous micropinocytotic vesicles can be seen in favorable sections. Within the cytoplasm are dense bodies, vesicles resembling micropinocytotic vesicles, peripheral vacuoles, and large central vacuoles. Dictyosomes and large mitochondria with few cristae and of low electron density are occasionally seen. It is suggested that material which is phagocytized by micropinocytosis may be combined with dense bodies, which may contain lytic enzymes, to form peripheral and thence central vacuoles where intracellular digestion would occur. The surface position of the hypodermal cells of the stalk or tubules makes them both likely candidates for a role in active ion uptake. The apparent lesser density of the tubule cuticle and greater abundance of mitochondria in the pear-shaped hypodermal cells of the tubules, compared with the stalk cuticle and hypodermis, indicates that the pear-shaped cells are more likely involved in such a process. Chloride localization with silver salts at the organ level indicates that the cuticle of tubules arising from the base and midsection of a gill stalk are strikingly more ion permeable than tubules from the tip, the stalk, or other parts of the whole body surface. This permeability difference correlates with a fine structure difference in tubular cuticle and pear-shaped cells depending upon their location. The cytoplasmic sheet of pear-shaped cells from the gill tip is thinner and may contain fewer mitochondria while the cuticle in this region has an epicuticle of higher electron density. Chloride localization with silver acetate at the fine structure level somewhat suggests the same base-to-tip differentiation and shows localization of the precipitated silver at the outer membrane of pear-shaped cells and cytoplasmic sheet. This suggests that the chloride pump is located in the outer membrane of the pear-shaped cells and cytoplasmic sheet located in the tubules of the lower half of the gills. |
| Genre | Thesis/Dissertation |
| Topic | Pacifastacus leniusculus |
| Identifier | http://hdl.handle.net/1957/47139 |
