PubMed · 160149
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Iu E Berezov, G I Perminova, A I Kovalev. 1979. [Laparoscopy in abdominal surgery].. https://pubmed.ncbi.nlm.nih.gov/160149/
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OBJECTIVE: To establish normal reference intervals for biparietal diameter, head circumference, abdominal circumference, and length of femur, a cross-sectional study. STUDY DESIGN: Five hundred singleton fetuses for each week at gestations between 23 and 41 weeks with a total of 9500 fetuses. Antenatal ultrasound measurements from all consecutive pregnant women referred to the ultrasound unit for scanning of fetal condition are prospectively entered in a data bank. For the purpose of this study, sonographic measurements were collected retrospectively and each fetus contributed just one value to the reference sample. RESULTS: The mean curve of the four biometrical parameters varied with gestational age, with flattening of the curves at the end of gestation and increased width of normal ranges with increasing gestational age. Maximal weekly increases occurred at 24 weeks' gestation for head circumference, abdominal circumference, and length of femur and at 26 weeks' gestation for biparietal diameter. The four biometrical parameters, however, showed 50% increases in size at 33 weeks' gestation. CONCLUSIONS: These fetal size reference intervals are clinically relevant and can be used for populations with epidemiological features and distribution of neonatal birth weights similar to our data.
Many species of the fruitfly Drosophila are either sexually dimorphic for abdominal pigmentation (the posterior segments in males are black and those of females have thin dark stripes) or sexually monomorphic for this pigmentation (both sexes show striping). Kopp et al. report a correlation in two Drosophila clades between the expression of the bric-à-brac (bab) gene, which represses male-specific pigmentation in D. melanogaster females, and the presence of sexually dimorphic pigmentation. They suggest that sexual selection acted to produce sexual dichromatism in Drosophila by altering the regulation of bab, on the grounds that D. melanogaster males show a strong mate preference for females with lightly pigmented abdomens, and that this discrimination helps to maintain sexual dichromatism by preventing males from wasting time by courting other (darkly pigmented) males. Here we show that the mate discrimination observed by Kopp et al. may in fact have resulted from the nature of the strains and comparisons they used in their study and so could be irrelevant to mate choice in nature.