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512.
Gabrielle J. Halpern Eliahu G. Stoupel Gad Barkai Rina Chaki Cyril Legum Moshe D. Fejgin Mordechai Shohat 《International journal of biometeorology》1995,39(2):59-63
We studied 2001 foetuses during the period of minimal solar activity of solar cycle 21 and 2265 foetuses during the period of maximal solar activity of solar cycle 22, in all women aged 37 years and over who underwent free prenatal diagnosis in four hospitals in the greater Tel Aviv area. There were no significant differences in the total incidence of chromosomal abnormalities or of trisomy between the two periods (2.15% and 1.8% versus 2.34% and 2.12%, respectively). However, the trend of excessive incidence of chromosomal abnormalities in the period of maximal solar activity suggests that a prospective study in a large population would be required to rule out any possible effect of extreme solar activity. 相似文献
513.
The synthesis of carrier-free β-32P-ribonucleosides triphosphate in almost quantitative yields is described. The procedures are based on a polynucleotide phosphorylase-catalyzed phosphorolysis of either poly- or oligoribonucleotides with carrier-free 32P-inorganic phosphate, coupled with a pyruvate kinase-catalyzed phosphorylation of the resulting β-32P-nucleoside diphosphate. 相似文献
514.
Mordechai Abraham Ezra Rahamim Hélène Tibika Esther Golenser Martin Kieselstein 《Cell and tissue research》1980,211(2):207-214
Summary Thin sections of normal testes from the cyprinodont Aphanius dispar were studied by electron microscopy after intravascular injection of live specimens with horseradish peroxidase. The intercellular space in the spermatogenic cysts is marked differently by the tracer according to the degree of differentiation of the germ cells. Spermatogonia and gonocytes undergoing meiosis are surrounded by a dark band of the marker. This band gradually disappears during spermiogenesis. In cysts containing ripe spermatozoa, the marker penetrates a short distance between the bases of adjoining Sertoli cells bordering the cysts, but is arrested by tight junctional complexes near the lumina of the cysts. The tight junctions between the Sertoli cells provide a permeability barrier between the vascular spaces of the stroma and the lumina of ripe cysts.Abbreviations
BM
basement membrane
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BTB
blood-testis barrier
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HRP
horseradish peroxidase
This research was supported by a grant from the National Council for Research and Development, Israel, and the GKSS Geesthacht-Tesperhude, Federal Republic of Germany 相似文献
515.