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L C Stephens T E Schultheiss K J Vargas D M Cromeens K N Gray K K Ang 《Journal of medical primatology》1989,18(5):383-396
The various glands of rhesus monkey eyelids and human eyelids are similar. Numerous modified sebaceous glands are located along the tarsus. These conform with the meibomian glands, while typical sebaceous glands associated with the hair follicles of the lashes are consistent with the glands of Zeis. Lobules of accessory lacrimal tissue, corresponding to the glands of Krause and Wolfring, are located in the conjunctiva of the fornix and along the orbital border of the tarsal plate. Goblet cells are plentiful in the mucosa of the palpebral and bulbar conjunctiva, and along the lid margin are the sweat glands of Moll. 相似文献
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The evolution of the mouse immunoglobulin heavy chain variable region (Igh-V) locus was investigated by the comprehensive analysis of variable region (Vh) gene family content and restriction fragment polymorphism in the genusMus. The examination of naturalMus domesticus populations suggests an important role for recombination in the generation of the considerable restriction fragment polymorphism
found at theIgh-V locus. Although the sizes of individualVh gene families vary widely both within and between differentMus species, evolutionary trends ofVh gene family copy number are revealed by the analysis of homologues of mouseVh gene families inRattus andPeromyscus. Processes of duplication, deletion, and sequence divergence all contribute to the evolution ofVh gene copy number. CertainVh gene families have expanded or contracted differently in the various muroid lineages examined. Collectively, these findings
suggest that the evolution of individualVh family size is not driven by strong selective pressure but is relatively neutral, and that gene flow, rather than selection,
serves to maintain the high level of restriction fragment polymorphism seen inM. domesticus. 相似文献
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Adele Post 《Polar Biology》1990,10(4):241-245
Summary Variation in leaf pigmentation from green to ginger is observed for Ceratodon purpureus (Hedw.) Brid. in Antarctica. Electron microscopy of ginger and green leaves reveals less thylakoid stacking, a response to greater light exposure, in the ginger leaves. In extremely exposed sites C. purpureus has low chlorophyll a/b ratios which correlate with decreased 77K chlorophyll fluorescence, indicating damage to chlorophyll a. Pigment analysis of ginger moss shows that even when the chlorophyll a/b ratio has not decreased the pigment composition differs from green moss. The increase in anthocyanin and decrease in chlorophyll concentrations largely account for the visual change from green to ginger. The ratio of total carotenoid to chlorophyll varies from 0.35 in green moss to 0.55 in the ginger moss, with violaxanthin increased preferentially. Since these changes in pigmentation are consistent with photoprotection and they are linked to light dependent variations in chloroplast structure, it appears that photoprotective pigments are a useful adaptation for the bright Antarctic environment. 相似文献
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Paulo E. Oliveira Peter E. Gibbs Ana Angélica Barbosa Salvador Talavera 《Plant Systematics and Evolution》1992,179(3-4):207-219
The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens. 相似文献
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The repopulation kinetics of the irradiated lip mucosa of mice has been investigated. Split-dose experiments showed that, in this tissue, repopulation starts within 3 days after the first irradiation and increases exponentially within 10 days. To assess the relative importance of protraction and distribution of irradiations as a function of time, 10 fractions were given in (1) 3 days (three irradiations per day with a 4-hr interval), (2) 11 days (daily fractions), or (3) two short courses, each consisting of five fractions given in 1.5 days separated by a rest period of 8 days, with an overall time of 11 days. The results show that by protracting the treatment from 3 to 11 days (with daily irradiations) repopulation accounts for recovery of approximately 13 Gy. Delivering the radiation in two short courses separated by a rest period leads to an additional recovery of approximately 5 Gy. The most plausible explanation for this observation is that repopulation is much more efficient during the rest period between the two courses than during continuous daily irradiation. Although the regimen of two short courses with a rest period spares the acute reaction, it will not enhance the late tolerance. Before thorough knowledge about the repopulation kinetics of the tumors can be gained, caution should be observed for indiscriminate use of split-course multiple-fraction-per-day (MFD) regimens for treating various tumors. 相似文献
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The effect of posture on maternal capillary blood Po2 and Pco2 was studied in pregnant and non-pregnant women. There was a significant decrease of Po2 (mean 13·0 mm. Hg) and significant decrease of Pco2 (mean 2·4 mm. Hg) when pregnant women sat up, but these changes did not occur in the non-pregnant. These findings may be relevant to debate on the optimum posture for labour. 相似文献