Rectal Gland Cells Research Articles

Actin polymerization and its regulation by proteins from nonmuscle cells.

Actin polymerization and its regulation by proteins from nonmuscle cells.

Ultrastructure of the tail region of the second stage preparasitic larva of the root-knot nematode

Studies on the tail of second-stage infective larvae (L 2s) of Meloidogyne javanica, M. incognita and M. hapla from a region anterior to the rectal gland to the tail tip have revealed the presence of a previously undescribed sensory organ, the caudal sensory organ, in the posterior region of the tail. The extreme tip of the tail consists of solid cuticle and the different zones of this structure are described throughout the tail region. Longitudinal sections through the anus and rectum have revealed that the cortical (external cortical, epicuticle) layer gradually decreases in thickness until its outermost layer appears to merge with the plasma membrane of the rectal inflation or gland. This gland appears to be similar in all three species studied. The two phasmidial glands and their canals are described from transverse sections. Somatic muscle is first found in the region of the anus and it extends anteriorly throughout most of the length of the L 2. Depressor ani muscles which insert on the dorsal surface of the rectum are also described. The rectal gland in the dilated state occupies about three quarters of the diameter of the L 2. It contains a matrix which resembles that extruded from the adult female rectal gland cells. The rectal gland cells contain large amounts of rough endoplasmic reticulum and desmosomes are found close to the junction of these cells and the plasma membrane of the gland itself. More anteriorly in the L 2 most of the area is taken up by large lipid droplets which function as an energy reserve. It is suggested that the rectal gland should not be used as a taxonomic criterion for separating the La 2 S of Meloidogyne because it can vary so much in appearance within the same species.

Physiological and morphological studies on secretion of a protein-carbohydrate complex by a nematode

Dropkin V. H. and Bird Alan F. 1978. Physiological and morphological studies on secretion of a protein-carbohydrate complex by a nematode. International Journal for Parcsitology 8: 225–232. Secretion of the gelatinous matrix by females of Meloidogyne javanica was induced by compounds extracted from the roots of either susceptible or resistant plants. The stimulus that induced this secretion was not specific but analysis of root extracts implicated the nucleic acids. DNA was the most active substance tested (minimum concentration = 0·0075 mg/ml). The response was rapid, usually within 10 min and did not appear to be nerve mediated. The shape of the exudate in vitro was conditioned by the composition of the medium in which the nematodes were tested. Stimulation brought about significant changes in the nuclei of the rectal gland cells which enlarged, in the nucleoli, which tended to become more granular and vacuolated, and in the cytoplasm, where there was an increase in the number of Golgi bodies per unit area.

Measurements of the bioelectric potentials in the rectum of Locusta migratoria and Carausius morosus in in vitro preparations

The potential profiles across the rectal gland epithelium in in vitro preparations of Locusta migratoria and Carausius morosus are investigated. The potential of the interior of the rectal gland cells lies in the range −45 mV ± 11 mV ( Locusta) and −37 mV ± 7 mV ( Carausius) with respect to the bathing medium, shortly after preparation. This potential remains relatively constant over several hours of experimental observation. The transepithelial potentials, however, have initial values of + 20 mV ± 5 mV ( Locusta) and + 5 mV ± 3 mV ( Carausius), the lumen of the rectum being positive with respect to the bathing medium. These potentials decrease to zero (or negative values in Carausius) over several hours' observation.

Electron microscopic histochemical studies on salt-excreting glands in elasmobranchs and marine catfish

Rectal glands of sharks ( Heterodontus ) and stringrays ( Urolophus ) and dendritic organs of marine catfish (Plotosidae) have been studied, using potassium antimonate for the demonstration of sodium, colloidal iron for acid mucopolysaccharides, the Wachstein-Meisel method for ATPase, and the lanthanum hydroxide method for the demonstration of extracellular spaces. It is shown that in these salt-excreting glands sodium is transported against a chemical gradient through the lateral plasma membranes of rectal gland cells and through the membranes of the tubules in the principal cells of the dendritic organ. Sodium ions are thus concentrated in the cytoplasm of the glandular cells. Contrary to sodium-absorbing epithelia where the cells are joined by zonulae occludentes, the salt excreting glands studied lack such tight junctions.