Henen Brian T, Hofmeyr Margaretha D
Department of Zoology, University of the Western Cape, Bellville 7535, South Africa.
J Exp Zool A Comp Exp Biol. 2003 May 1;297(1):88-104. doi: 10.1002/jez.a.10234.
Ultrasonography is a powerful new tool in reproductive physiology and ecology but quantitative evaluations of acoustic window efficacies are necessary to assess methodological accuracy. We evaluated the efficacy of the left inguinal, right inguinal and cranial acoustic windows for detecting ovarian follicles and oviducal eggs in three tortoise species. Incorporating cranial results improved upon inguinal efficacies for detecting follicles in the three species, and for detecting eggs in Chersina angulata, which had small inguinal apertures for its body size. The cranial window provided the best follicle results (highest numbers detected) but the left inguinal window provided the best egg results. This asymmetry was probably due to the primarily posterior position of the oviducts (eggs) and the pliable ovarian sheets allowing follicles to move cranially. The left-right asymmetry may result from intestinal asymmetry (i.e., between the cecum and descending colon) in obscuring ultrasound transmission or displacing follicles and eggs. Seasonal influences upon efficacies varied with species, partially due to species differences in a) reproductive cycles and b) size and number of follicles and eggs. We attributed other efficacy differences among species to differences in body size and shell morphology, especially the inguinal apertures. Correlation analyses revealed strong individual influences upon window efficacy, suggesting that individuals varied in the position of follicles and eggs and the degree of obfuscation by nonreproductive structures. The paucity of correlations between efficacies and body size reflects the complex interactions of body size, shell morphology, reproductive structures and reproductive cycles on efficacies.
超声检查是生殖生理学和生态学中一种强大的新工具，但对声学窗口效能进行定量评估对于评估方法的准确性是必要的。我们评估了左腹股沟、右腹股沟和颅部声学窗口在三种龟类中检测卵巢卵泡和输卵管卵的效能。纳入颅部检查结果后，在检测三种龟类的卵泡以及检测安哥洛卡象龟（因其体型腹股沟开口较小）的卵时，腹股沟检查的效能有所提高。颅部窗口在检测卵泡方面效果最佳（检测到的数量最多），但左腹股沟窗口在检测卵方面效果最佳。这种不对称可能是由于输卵管（卵）主要位于后方，以及柔韧的卵巢片使卵泡能够向颅部移动。左右不对称可能是由于肠道不对称（即盲肠和降结肠之间）遮挡超声传播或使卵泡和卵移位所致。效能的季节性影响因物种而异，部分原因是物种在以下方面存在差异：a）生殖周期，b）卵泡和卵的大小及数量。我们将物种间其他效能差异归因于体型和壳形态的差异，尤其是腹股沟开口。相关性分析揭示了个体对窗口效能有强烈影响，这表明个体在卵泡和卵的位置以及非生殖结构的遮挡程度方面存在差异。效能与体型之间缺乏相关性反映了体型、壳形态、生殖结构和生殖周期对效能的复杂相互作用。
