P2.76 Thursday, Jan. 5 Development of the Hypothalamus and Pituitary Gland in the Snapping Turtle, Chelydra serpentina GRUCHALLA, K.L.*; RHEN, T.E.; University of North Dakota; University of North Dakota firstname.lastname@example.org
The hypothalamus and pituitary gland regulate the endocrine system in all vertebrates in order to maintain homeostasis. Development of the hypothalamic-pituitary axis has been well-studied in mammals and birds, however documentation in reptiles is lacking. Previous studies have shown the hypothalamus originates early in development from the diencephalon, later differentiating into distinct nuclei. The brain begins as a bipotential organ that will develop either a masculine or feminine phenotype; sex steroids produced by the developing gonads are implicated in establishing sexual dimorphisms. Proper organization of the hypothalamus during early development is important later in life for control of gonadal function as well as activation of sex-appropriate reproductive behavior. The snapping turtle displays temperature-dependent sex determination, which makes it a useful model species to study the development of sexual dimorphisms because it allows for the control of sex. The pituitary gland develops concomitantly, originating from two separate tissues: the anterior pituitary gland arises from oral ectoderm, whereas neural ectoderm forms the posterior lobe. This study aims to establish a developmental record of the hypothalamus and pituitary gland in the snapping turtle and determine areas of sexual dimorphism in both regions. Throughout development we employed a morphological analysis and stereology, an unbiased method to evaluate potential differences in cell number and hypothalamic nuclear volume. This record will act as a starting point for further studies involving hypothalamus and pituitary gland development and characterization of sexual dimorphisms in these regions.