Figure 1.

Growth and development of the Aedes aegypti larval midgut. Midguts from 1^st through 4^th instars were dissected, fixed and stained with Hematoxylin and DAPI. First through 3^rd instar midguts were dissected approximately 12 hours after the molt. Fourth instar midguts were dissected 24 hours after the molt. The left side image of each pair was taken using autofluorescence (green) or bright field (red), to emphasize the boundaries of the cells. The right side image is the same field of view showing DAPI stained nuclei. All images were taken at the same magnification and the scale bar represents 200 µm. Large nuclei are indicated by downward pointing arrow heads. Intermediate sized nuclei are indicated by upward pointing arrow heads. Small oval nuclei are indicated by left pointing arrows, (a) 1^st instar anterior midgut had uniformly spaced large nuclei with interspersed small nuclei, (b) 1^st instar posterior midgut had uniformly spaced large nuclei with interspersed small nuclei, (c) 2^nd instar anterior midgut had uniformly spaced large nuclei and more interspersed smaller and intermediate sized nuclei, (d) 2^nd instar posterior midgut had uniformly spaced large nuclei and numerous interspersed smaller and intermediate sized nuclei, (e) 3^rd instar anterior midgut had uniformly spaced large nuclei that were surrounded by numerous intermediate and small sized nuclei, (f) 3^rd instar posterior midgut had uniformly spaced large nuclei and many intermediate and small sized nuclei surrounding the large nuclei, (g) 4^th instar anterior midgut had large and intermediate sized nuclei surrounded by small elongate nuclei, (h) 4^th instar posterior midgut also had large and intermediate sized nuclei surrounded by elongate small nuclei.