Date of Award:

5-1-1984

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Warren C. Foote

Committee

Warren C. Foote

Committee

Jay W. Call

Committee

Keith L. Dixon

Committee

LeGrande C. Ellis

Committee

Raymond T. Sanders

Abstract

Groups of at least six ewes each during the estrous and anestrous seasons were estrus synchronized using progesterone implants and superovulated using follicle stimulating hormone (FSH) or pregnant mare serum gonadotropin (PMSG), or left as nonsuperovulated controls. Ewes were sacrificed 30 h after removal of implants. The hypothalamus, adenohypophysis and ovaries were removed and frozen in liquid nitrogen. Frozen sections of all tissues were incubated with radiolabeled hormones to determine location and quantity of receptor sites. Slides were dipped in autoradiography emulsion and allowed to self expose 10 days before they were developed and stained. Slides were then examined using a micro-spectrophotometric system, and photometric readingswere taken of various cell types for the tissue sections. Estrus synchronization for all treatments was more successful for animals in the estrous season than during seasonal anestrus. Season, treatment, and season and treatment interaction made a significant difference on the size of follicle. Hypothalamic estrogen receptor sites showed significant differences due to treatment, area; and season-treatment-area interaction. The pituitary showed receptor sites for GnRH, FSH and LH. Significant differences in binding were due to season, treatment and cell type, as well as the season and treatment interaction. It is proposed that FSH and LH receptors are responsible for fine tuning of GnRH receptors and switchover from FSH to LH secretion. Ovarian binding of FSH and LH is influenced by season, the cell type, bilateralness of the ovaries and the interaction of treatment with several other factors. Interactions of these factors followed predictable patterns. A theory involving speed of response due to different treatments is proposed to explain results found in this study.

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .