Embryonic Structures Commons^™

The Effects Of 17Α-Ethynylestradiol (Ee2) On Gonadal Development And Differentiation In The Estuarine Killifish, Fundulus Heteroclitus, Ibrahim Chehade

Theses and Dissertations (Comprehensive)

Endocrine disrupting substances (EDSs) comprise a wide variety of chemicals that perturb normal endocrine function including developmental and reproductive processes in vertebrates. The synthetic estrogen 17α-ethynylestradiol (EE₂) is a commonly-used model EDS because of its environmental relevance and its effects on the reproductive endocrine system. Early life-stage exposure of fish to estrogenic EDSs causes effects such as intersex (ovotestes in males) and feminization. This study aims to confirm the period of gonadal differentiation in the estuarine killifish or mummichog (Fundulus heteroclitus) and to determine the sensitivity of gonadal development to EE₂. Artificially-regressed mummichog were spawned, and fertilized eggs ...

The Role Of Sonic Hedgehog In The Hypothalamus, Solsire E. Zevallos

Publicly Accessible Penn Dissertations

ABSTRACT

THE REQUIREMENT OF SONIC HEDGEHOG IN THE HYPOTHALAMUS

Solsire E. Zevallos

Douglas J. Epstein

Sonic hedgehog (Shh) is a morphogen secreted during early development that is required for the formation of the ventral neural tube, including the ventral forebrain. The prechordal source of Shh underlying the forebrain is required early to bifurcate the cerebral hemispheres and eye vesicles as well as to specify a rostroventral forebrain region, the hypothalamus. We hypothesized that Shh expressed later in the hypothalamus may be required for other known functions of Shh, such as patterning within a region, cell proliferation, cell specification, and axon ...