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Embryonic integument and "molts" in Manduca sexta (Insecta, Lepidoptera)
1Institut für Zoologie, Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
Journal of Morphology
|December 11, 2002
Summary
The Manduca sexta embryo forms three protective layers during development, with the second layer differing in structure from those in hemimetabolous insects. This difference may reflect evolutionary adaptation and reduced embryonic covers.
Area of Science:
- Developmental Biology
- Insect Embryology
- Evolutionary Biology
Background:
- The Manduca sexta embryo undergoes significant morphological changes during its development.
- Understanding the formation of embryonic membranes and cuticles is crucial for insect embryology.
Purpose of the Study:
- To examine the deposition of embryonic membranes and cuticles in Manduca sexta using electron microscopy.
- To compare the embryonic covers of Manduca sexta with those of hemimetabolous insects.
Main Methods:
- Electron microscopy was used to observe the ultrastructure of embryonic membranes and cuticles.
- Developmental stages of Manduca sexta embryos were analyzed post-oviposition.
Main Results:
- Manduca sexta embryos secrete three covers during development, similar to hemimetabolous insects.
- The second embryonic cover in Manduca sexta has a membranous, cuticulin-like structure, unlike the cuticular organization in hemimetabolous insects.
- Epidermal cells exhibit distinct features, including yolk uptake, microvilli formation, and organelle changes, correlating with membrane deposition.
Conclusions:
- The structural difference in the second embryonic cover of Manduca sexta may be an evolutionary adaptation related to redundant embryonic covers.
- Embryonic molts are a conserved feature across arthropods, with phylogenetic implications.