Honors Program Theses


Open Access Honors Program Thesis

First Advisor

Darrell Wiens


During secondary neurulation, the tail bud of the developing chick embryo undergoes a transition from unorganized mesenchymal cells to a structured epithelial tube. Cells undergoing this process must polarize and then assemble specific molecules that allow them to create intercellular junctions. Intercellular junctions contribute to the cells' ability to adhere, communicate with each other, or block the movement of molecules between neighboring cells. Previous studies have suggested cell-to-cell junctions play an important role in cavitation of the tail bud and in organizing the lumina that form. This study aimed to determine if tight junctions and gap junctions develop in this region and, if so, how they contribute to the normal process of secondary neurulation.

Using immunolocalization techniques and microscopy, the gap junction protein connexin-43 was found in early cells of the tail bud mesenchyme, and present in the apical and basal ends of cells of the incipient secondary neural tube. The tight junction protein PAR-3 was localized within the tailbud mesenchyme, with possible intercellular linear arrangements of the protein in the apical ends of the cells surrounding forming lumina. The localization of the tight junction protein Z0-1 at the apical ends of cells surrounding the neural tube lumen was observed. The tight junction immunolocalization results were preliminary and should be further tested. It is suggested that gap junctions play a role in organizing and synchronizing cells during secondary neurulation, while tight junctions likely help establish apical-basal polarity in cells during secondary neurulation. Finally, it was discovered that location oflumina formation varies among individual chick embryos.

Year of Submission



Department of Biology

University Honors Designation

A thesis submitted in partial fulfillment of the requirements for the designation University Honors


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Date Original


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