Date of Award:

5-1-1969

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Physiology

Committee Chair(s)

LeGrande C. Ellis

Committee

LeGrande C. Ellis

Abstract

This investigation attempts to determine the relative importance of the two most widely accepted pathways for the biosynthesis of estrogens namely the Δ4 pathway and the Δ5 pathway. These pathways were compared in both normal and transplanted ovarian tissue using the double isotope dilution technique with 7⍺-H3-pregnenolone and 4-C14-progesterone. The effects of ovarian transplants into peripheral tissue on steroid biosynthesis in vitro, uterine weights, adrenal weights, thymus weights, and estrus cycles in vivo were noted. One ovary from each animal was transplanted to the dorsal aspect of the ear while the other ovary was used in normal tissue incubation. The transplanted tissue was left in place for varying lengths of time while the estrus cycles were checked each day by vaginal smear. The cycles were monitored for a minimum of two weeks before the animals were sacrificed and incubations made with the transplanted tissue. The uterine, adrenal, and thymus weights from the animals with transplants were then compared to those for normal organs. Estrus cycles were reestablished in the animals with transplants and remained near normal in length for varying lengths of time. However, after prolonged periods after the operation, the cycles of most animals became irregular and many went into continuous estrus. The uteri of the animals receiving transplants were significantly larger than those of intact animals, while the thymi were smaller in the animals with transplants indicating an increase in estrogen production. This was found to be true in the in vitro incubation studies with labeled precursors. The steroid biotransformations showed significant differences between normal and transplanted ovarian tissue with the transplanted tissue showing a higher percentage of conversion of radioactive precursors to estrogens than normal tissue. There also appeared to be a greater utilization of the Δ5 pathway in the transplanted tissue than in normal tissue.

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