Curtis N J, Ringo J M, Dowse H B
Department of Biological Sciences, University of Maine, Orono 04469-5751, USA.
J Morphol. 1999 Jun;240(3):225-35. doi: 10.1002/(SICI)1097-4687(199906)240:3<225::AID-JMOR2>3.0.CO;2-V.
The early pupal heart of the fruit fly Drosophila melanogaster has recently been the subject of intense physiological and molecular work, yet it has not been well described, nor has it been compared with the heart of the adult fly. In the work reported here, the hearts of adults and early pupae of D. melanogaster were studied by scanning and transmission electron microscopy and by light microscopy. The hearts of adults and early pupae both consist of a tube of circular striated muscle one cell in thickness. The alary muscles, which suspend the heart, are more delicate in the adult compared to the early pupa. The pericardial cells in both early pupae and adults are connected to the heart by connective tissue radiating from the alary muscles or dorsal diaphragm. We confirm that four major changes occur in the heart during metamorphosis: 1) a conical chamber is formed de novo in the first and second abdominal segments; 2) the adult heart curves to conform to the contour of the abdomen; 3) a layer of longitudinal striated muscle appears on the ventral surface of the heart; 4) a fourth pair of ostia is added to the three already present in the early pupa; and note additionally that 5) the ostia appear as simple openings in the heart of the early pupa but are valve-like in the adult.
果蝇黑腹果蝇的早期蛹心脏最近成为了深入生理和分子研究的对象，但它尚未得到充分描述，也未与成年果蝇的心脏进行比较。在本文报道的研究中，通过扫描电子显微镜、透射电子显微镜和光学显微镜对黑腹果蝇成虫和早期蛹的心脏进行了研究。成虫和早期蛹的心脏均由一层厚度为一个细胞的环形横纹肌管组成。悬挂心脏的翼肌在成虫中比在早期蛹中更为纤细。早期蛹和成虫的围心细胞均通过从翼肌或背膈辐射出的结缔组织与心脏相连。我们证实，在变态过程中心脏会发生四个主要变化：1）在第一和第二腹节中从头形成一个锥形腔；2）成年心脏弯曲以符合腹部轮廓；3）心脏腹面出现一层纵向横纹肌；4）在早期蛹已有的三个气门之外增加第四对气门；此外还注意到5）早期蛹心脏中的气门表现为简单的开口，而在成虫中则呈瓣膜状。
