Development of the dendrobatid frog Colostethus machalilla

Area of Science:

• Developmental Biology
• Amphibian Embryology
• Comparative Morphology

Background:

• The dendrobatid frog, Colostethus machalilla, reproduces in captivity, laying terrestrial eggs.
• Parental care involves paternal guarding of embryos until tadpole hatching.
• Understanding C. machalilla development provides a correlate for other frog species.

Purpose of the Study:

• To create a normal table of development for Colostethus machalilla.
• To analyze the early embryonic morphology of C. machalilla.
• To compare C. machalilla development with other frog models like Xenopus laevis.

Main Methods:

• In vitro culture of C. machalilla embryos.
• Observation of external and internal morphology (whole mount and sections).
• Immunostaining using neural, notochord, and somite specific antibodies to analyze gene expression.

Main Results:

• Embryonic development of C. machalilla is slow and distinct from Xenopus laevis.
• Notochord, neural plate, and somite formation occur post-blastopore closure, suggesting delayed dorsal convergence.
• Gastrulation deviates, with a small archenteron and accumulation of cells at blastopore lips, forming a thick structure resembling an embryonic disk.

Conclusions:

• Colostethus machalilla exhibits unique developmental stages and gastrulation patterns compared to Xenopus laevis.
• Delayed morphogenetic movements may explain observed developmental deviations.
• The thick blastopore lips of C. machalilla present an interesting alternative to the embryonic disk observed in other species.