Stages of embryonic development in the live-bearing fish, Gambusia holbrooki
Divergent morphology and placentation of Poeciliids make them suitable model for investigating how evolutionary selection has altered and conserved the developmental mechanisms. However, there is limited description of their embryonic staging, despite representing a key evolutionary node that shares developmental strategy with placental vertebrates. Here we describe the embryonic developmental stages of Gambusia holbrooki from zygote to parturition using freshly harvested embryos.
We defined 40 embryonic stages using a numbered (stages 0-39; zygote to parturition respectively) and named (grouped into seven periods that is, zygote, cleavage, blastula, gastrula, segmentation, pharyngula and parturition) staging system. Two sets of quantitative (ie, egg diameter, embryonic total length, otic vesicle closure index, heart rates, the number of caudal fin rays and elements) and qualitative (ie, three-dimensional analysis of images and key morphological criteria) data were acquired and used in combination to describe each stage. All 40 stages are separated by well-defined morphological traits, revealing developmental novelties that are influenced by narrow perivitelline space, placentation, internal gestation, and sex differentiation.
The principal diagnostic features described are quick, reliable, and easy to apply. This system will benefit researchers investigating molecular ontogeny, particularly sexual differentiation mechanisms in G. holbrooki.
Publication titleDevelopmental Dynamics
Department/SchoolInstitute for Marine and Antarctic Studies
PublisherJohn Wiley & Sons Inc
Place of publicationUnited States
Rights statementCopyright 2021 American Association for Anatomy