Fig. 2
From: Development of the indirect flight muscles of Aedes aegypti, a main arbovirus vector
Dorso-coronal sections of the thoracic region of late L4 show fascicles corresponding to DLMs. Myotubes in each fascicle are showed in oblique sections. a, b Each DLM fascicle (three each side, right and left, labeled as 1, 2 and 3) is formed by four myotubes. a At this section level fascicles 1 are attached by the anterior side to the thoracic epithelium in upper thorax (black arrowheads). b In this plane attachment of DLM fascicles numbered 2 and 3 to the thoracic epithelium is to the lower thorax (black arrowheads) and fascicles 1 are out of focus in the histological section. c Detail of attachment region of DLM myotubes 3 and 2, where myotendinous junctions (MTJ) are observed (black arrowhead; d and d′, dorsal). d Detail of fascicle 3 where possible fusion competent myoblasts (fcm) are observed between four myotubes. e DLM primordia in the thoracic region of L4 instar. At this oblique section the three fibers per hemithorax are captured (numbered 1, 2, 3), each fascicle formed by four fibers (red asterisks). Those fascicles corresponding to the LOMs or scaffold myotubes, possibly in splitting process. Several myoblasts among fibers are observed (spots among fibers). Myotendinous junctions (MTJ) formed between front side end of myotubes, and thoracic epithelial cells are shown (green arrows). The posterior end of myotube is suspended in the hemocoel and structures suggesting the start of MTJ formation are seen (green arrowheads). Red arrows point to the cephalic side. ct cuticle, ep epidermis, fcm fusion competent myoblasts, fb fat body, gc gastric caeca. Scale bars: a, b, e 500 µm; c 150 µm; d 100 µm