An Observational and Experimental Analysis of Embryonic Development and Cardiac Neural Crest Migration in the Turtle

Date of Completion

5-5-2023

Degree Type

Honors Thesis - Campus Access

Discipline

Biology (BIOL)

First Advisor

Dr. Max Ezin

Abstract

The following project amalgamates observation skills, embryonic development, and cardiac neural crest cell migration to offer a comprehensive presentation of biological analysis. Developmental biology requires sharp observation skills to detect details in images of microscopic features. Yet, current training in developmental biology does not emphasize observation and quantitative analysis of microscopic images, and it is unclear how best to teach students these skills. Here, undergraduate students used representational drawing to enhance skills in observation of fine cellular details in images of microscopic features in chick embryos. Results suggest that visual arts hone and engage students’ observation skills when analyzing images of cells and tissues. With this sharpened observation ability in hand, students then embarked on a descriptive study of the embryonic development of the Trachemys scripta turtle.

Although it holds a unique place in vertebrate evolutionary history, the turtle is rarely used as model organisms due to the scarcity of experimental tools adapted for it. In this project, we created a full developmental staging series of T. scripta from 0 days post-oviposition (dpo) to hatching (~60 dpo), implementing a newly-emerged “standard event system” (SES) model to standardize and compare T. scripta development to other vertebrate species. The completed staging series then served as a tool to guide experimental work with the turtle. SES criteria were first used to establish equivalent stages between turtles and chickens at developmental timepoints relevant to cardiac neural crest migration. HNK1 antibody staining and neural tube injections reveal a similar migration pattern between chickens and turtles, despite differences in the streams of neural crest cells themselves. Altogether, these projects offer insights into the evolutionary significance of the three chambered heart and the role of neural crest cells in its formation.

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