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Measurement of flow speed in the channels of novel threadlike structures on the surfaces of mammalian organs 总被引:1,自引:0,他引:1
There have been several reports on novel threadlike structures (NTSs) on the surfaces of the internal organs of rats and rabbits
since their first observation by Bonghan Kim in 1963. To confirm this novel circulatory function, it is necessary to observe
the flow of liquid through the NTS as well as the structurally corroborating channels in the NTS. In this article, we report
on the measurement of the flow speed of Alcian blue solution in the NTSs on the organ surfaces of rabbits, and we present
electron microscopic images depicting the cribrous cross-section with channels. The speed was measured as 0.3 ± 0.1 mm/s,
and the flow distance was up to 12 cm. The flow was unidirectional, and the phase contrast microscopic images showed that
the NTSs were strongly stained with Alcian blue. The ultrastructure of the NTSs revealed by cryo-scanning electron microscopy
and high-voltage electron microscopy showed that (1) there were cell-like bodies and globular clumps of matter inside the
sinus of the channel with thin strands of segregated zones which is a microscopic evidence of the liquid flow, (2) the sinuses
have wall structures surrounded with extracellular matrices of collagenous fibers, and (3) there exists a cribriform structure
of sinuses. To understand the mechanism for the circulation, a quantitative analysis of the flow speed has been undertaken
applying a simplified windkessel model. In this analysis, it was shown that the liquid flow through the NTSs could be due
to peristaltic motion of the NTS itself.
Baeckkyoung Sung and Min Su Kim contributed equally to this work. 相似文献
277.
Wendy Fjellstad Klaus Mittenzwei Wenche Dramstad Eva Øvren 《Environmental Science & Policy》2009,12(8):1144-1152
Norwegian Protected Landscapes aim to preserve landscape character. As most of the agricultural land in Protected Landscapes is privately owned, the attitudes and behaviour of farmers are crucial in achieving this goal. We present results of a nationwide questionnaire to farmers who owned or managed farmland in Protected Landscapes. Thirty-eight percent of the respondents claimed that their farm business had been changed as a consequence of landscape protection. Niche products and alternative income possibilities, commonly forwarded as potential benefits of landscape protection status, had generally not been realised. Although we found that most farmers agreed on the importance of taking care of cultural landscapes, 76% felt that this was best done by using rather than protecting the landscape. The study revealed negative attitudes towards municipal authorities. A quarter of respondents were strongly against the establishment of new Protected Landscapes, even if they were compensated for economic losses. Based on results of the study we suggest that major improvements to the protection system could be made by improving communication between management authorities and farmers, and ensuring real involvement of farmers in making and carrying out management plans. 相似文献
278.
Most studies on insect sperm motility have been conducted in vitro using artificial environments outside the animal’s body.
Only little is known about the function of motile insect sperm at different sites within the male or female genital tracts.
We dissected genital tracts of female rove beetles (Drusilla canaliculata) to show that spermatozoa use their own motility to migrate from the spermatophore into the spermatheca. Our dissection method
allowed direct observation and filming of the spermathecal filling process inside the female’s genital tract. Spermatozoa
were found to enter the spermatheca individually, sometimes in groups of two or three. Although exhibiting only weak motility
and no progressive motion in buffer solution, the spermatozoa inside the female show vigorous lashing and reach an average
velocity of 47.5 μm s−1. To gain mobility and speed, the spermatozoa likely utilize the relatively small diameter of the spermathecal duct to push
themselves off the duct walls, rather than swimming freely in seminal fluid. The spermatozoa (approximately 1,250 μm) are
considerably longer than the distance they have to travel along the spermathecal duct (approximately 800 μm). Our study provides
the first direct observation of active sperm migration within the female of an insect stressing the importance of the genital
tract as a prerequisite for functional sperm motility. 相似文献
279.
By reducing the attractiveness of their mating partner via an anti-aphrodisiac pheromone, males can prevent a remating of the female and thus reduce the risk of sperm competition. For females, the main benefit from allowing the chemical manipulation of their attractiveness is probably the avoidance of sexual harassments from rival males. While mating plugs generally constitute a physical barrier which hinders male mating attempts, chemical manipulations must trustfully inform the responding male of the female's reluctance to mate; otherwise, it would be beneficial to ignore the repellent information. In our experiments, males of the polyandrous rove beetle Aleochara curtula chemically manipulated the attractiveness of their mating partner. Coincident with the deposition of a spermatophore into the female genital chamber, an anti-aphrodisiac pheromone was transferred and readily spread onto the female surface, where it was subsequently perceived by rival males via parameres, the claspers of the male genitalia. Males aborted contact with the mated female to avoid further time- and energy-consuming elements of the mating sequence. The chemical mode of action was demonstrated inter alia by spicing virgin females with spermatophore extracts. The action of the anti-aphrodisiac correlated with the persistence of the spermatophore in the female genital chamber and corresponded to the length of stay of the mated female at a carcass, where the density of rival males is highest. The ensuing benefits for all three parties involved in this communication system, which render this post-copulatory mate guarding strategy evolutionary stable, are discussed. 相似文献
280.
Jong-Beom Seo Soo-Bin Jeon Je-Young Kim Gang-Woo Lee Jong-Hyeon Jung Kwang-Joong Oh 《环境科学学报(英文版)》2012,24(3):494-498
Aqueous ammonia (NH3) solution can be used as an alternative absorption for the control of CO2 emitted from flue gases due to its high absorption capacity, fast absorption rate and low corrosion problem. The emission of CO2 from iron and steel plants requires much attention, as they are higher than those emitted from power plants at a single point source. In the present work, low concentration ammonia liquor, 9 wt.%, was used with various additives to obtain the kinetic properties using the blast furnace gas model. Although a solution with a high ammonia concentration enables high CO2 absorption efficiency, ammonium ions are lost as ammonia vapor, resulting in reduced CO2 absorption due to the lower concentration of the ammonia absorbent. To decrease the vaporization of ammonia, ethylene glycol, glycerol and glycine, which contain more than one hydroxyl radical, were chosen. The experiments were conducted at 313 K similar to the CO2 absorption conditions for the blast furnace gas model. 相似文献