In both in vitro and in vivo experiments, polycationic macromolecules, such as poly(L-lysine), inhibited the transport of either surrogate or freshly ovulated cumulus masses across the oviduct epithelial surface without affecting the ciliary beat. Whereas transport across the fimbria in vivo was completely inhibited, transport down the ampulla was 3 to 7 times slower than normal. The effects of these polycations suggest that cilia-mediated ovum transport may involve the formation of transient adhesive bonds between the tip of the cilium and elements of the cumulus mass during each beat cycle of the cilium.Numerous studies have shown that once the ovum with its surrounding cumulus mass is discharged from the ovary, it is rapidly transported over the fimbrial surface of the oviduct and down the ampulla to the ampullar-isthmic junction (1). The ovum remains at the junction for several hours where the cumulus mass is removed; eventually, the denuded ovum travels through the isthmus to the uterus. Until recently, it has been generally accepted that the cilia of the epithelial cells that line the oviduct are responsible for movement of the cumulus over the fimbria into the ampulla and that the contractile activity of the smooth muscle cells in the wall of the ampulla is responsible for transporting the cumulus down the oviduct to the ampullar-isthmic junction (14). However, recent experiments by Halbert et al. (5,6) have shown that pharmacological inhibition of smooth muscle contractility does not impair cumulus transport in the ampulla, which suggests that smooth muscle contractility may not be the primary propulsive force in this region of the oviduct. The effects of muscle activity alone on ovum transport in the ampulla have not been determined because of the unavailability of a method specifically to inhibit cilia activity.The coordinate beating of cilia creates fluid currents over the oviduct epithelial surface, and these fluid movements have been proposed to be involved in moving the ovum (7,8). If this is the mechanism of ovum transport, then the cumulus is a passive agent that i carried in a "stream" of fluid over the epithelial surface. The only way to interfere with this process would be to alter the beating of the cilia severely enough to eliminate the surface fluid currents.Recently we reported that the portion of the rabbit oviduct ciliary membrane that covers the tip of the cilium has a high density of negative charges (9). By using polycationic ferritin as a specific electron-dense probe for anionic sites, we have shown that the probe binds to the tips of the cilia and that this binding is probably due to the presence of sialic acid-containing proteins at this site on the membrane. Evidence from other workers suggests that this might be a general property of ciliary membranes (10).The existence of negative charges on a portion of the ciliary membrane that would most likely interact with elements of the cumulus mass during ovum transport suggests that some type of electrostatic interaction betwee...
Polycationic ferritin (PCF) was used as a visual probe for anionic sites on the oviduct ciliary membrane. The binding of PCF to ciliary membranes was dependent on the concentration of the probe in the incubation media. At low concentrations (0.08-0.16 mg/ml), PCF was bound exclusively to the tip of the cilium whereas at higher concentrations (0.32-0.64 mg/ml), ferritin was located at the tip and at the base around the transition region, with occasional scattered clumps on the remainder of the membrane. The base and tip binding was found to be associated with special surface modifications of the membrane in these regions. At the tip, PCF was bound to a filamentous glycoealyx termed the ciliary crown. Base binding was associated with a system of five to six 140-/~ high ridges, each of which encircled the membrane of the transition region. The ridges were equally spaced (-245/~ spacing) along the length of the transition region. Since pretreatment of oviduct with either neuraminidase or protease blocked the binding of the probe, the PCF-binding sites appear to be negatively charged glycoproteins or mueopolysaccharides.The ciliary membrane is an important component of the cilium that is involved both in the regulation of ionic and metabolic states within the axoneme (7, 22) and in determining specific interactions with its environment (24, 25). Electron microscope studies show that this membrane sometimes has special surface modifications, e.g., hair-like appendages on Chlamydomonas flagella called mastigonemes (16). In addition, most cilia have two to six rows of intramembrane particles that encircle the basal portion of the membrane. These particles, termed the ciliary necklace (11,21,23,28), are thought to be involved in the regulation of ion transport (11). The remainder of the membrane usually has randomly distributed intramembrane particles; however, in some cases, there are rows of particles that run the longitudinal length of the cilium (23), or short longitudinally oriented rows of particles (the ciliary plaque [20,23]) that are located just above the ciliary necklace.The oviduct ciliary membrane has a ciliary necklace consisting of six rows of particles (11), randomly arranged intramembrane particles in the rest of the membrane, and a surface modification at the tip of the cilium called the ciliary crown (5). In a longitudinal view, this crown structure appears to be composed of a tuft of 225-A-long fibers covering the surface of the tip; however, in cross section, it appears to be a system of ridges that cover the membrane. The ciliary crown has also been found on the tips of thymic cyst cilia in "nude" mice (3), and a similar surface modification is found on the tips of oral cilia in Tetrahymena pyriformis (23). 4,82
Both the hormone dependency and the morphological details of estrogen-dependent ciliogenesis in the shell gland of the chick oviduct were investigated. Ciliogenesis was initiated on day 3 of estrogen treatment, and progressively more cells became differentiated until, on day 10, approximately 55% ciliation occurred with 17 beta-estradiol (1 mg/day) and approximately 75% ciliation occurred with diethylstilbestrol (1 mg/day). Simultaneous administration of progesterone with diethylstilbestrol (1 mg each/day for 10 days) caused a 50% depression in the number of ciliated cells on day 10. The rate of ciliogenesis was found to be affected by progesterone and the type of estrogen administered. The minimum stimulatory dose of estradiol was found to be between 0.01 mg/day and 0.05 mg/day. Ciliogenic cells were first recognized by the appearance of pro-basal bodies in the apical portion of the cell. Pro-basal body maturation and cilium formation were the same as those described for the chick trachea. Ciliogenesis in the chick was found to be homologous to estrogen-dependent ciliogenesis in various mammalian oviducts.
Simultaneous measurements of pulmonary oxygen consumption (VO ), carbon dioxide exhalation (VCO ) and phosphorus magnetic resonance spectroscopy ( P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO and VCO whilst simultaneously performing P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer. The use of a non-magnetic pneumotachograph and extension of the sampling line from 3 m to 5 m to place the spirometric device outside the MR scanner room did not affect adversely the measurements of VO and VCO . Response and delay times increased, on average, by at most 0.05 s and 0.79 s, respectively. Overall, we were able to demonstrate a feasible ventilation response (VO = 1.05 ± 0.31 L/min; VCO = 1.11 ± 0.33 L/min) during the exercise of a single calf muscle, as well as a good correlation between local energy metabolism and muscular acidification (τ and pH; R = 0.73, p < 0.005) and global respiration (τ and VO ; R = 0.55, p = 0.01). This provides improved insights into aerobic and anaerobic energy supply during strong muscular performances.
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