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Dissertation Information for Stephen Michael Downs

NAME:
- Stephen Michael Downs
- (Alias) Stephen Downs

DEGREE:
- Ph.D.

DISCIPLINE:
- [No Discipline Recorded]

SCHOOL:
- University of Iowa (USA) (1982)

ADVISORS:
- None

COMMITTEE MEMBERS:
- None

MPACT Status: Incomplete - Not_Inspected

Title: PREOVULATORY FOLLICULAR DEVELOPMENT IN IMMATURE SUPEROVULATED MICE: A STUDY OF THE POSSIBLE ROLE OF PROSTAGLANDINS

Abstract: "In this study, the possible role of prostaglandins in preovulatory follicular development was examined. Prostaglandins (PGs) have been implicated as essential mediators of follicular rupture. It was hypothesized that treatment of immature superovulated mice with the PG synthetase inhibitor, indomethacin, would suppress ovulation and, coincidentally, alter preovulatory follicular morphology. The resultant changes brought about by this agent would, it was reasoned, be attributable to its inhibitory action on PG synthetase and provide evidence for the role of PGs in specific developmental processes occurring prior to ovulation.

Indomethacin most effectively inhibited ovulation when administered in a dose of 10 mg/kg within 2 hours of the ovulatory gonadotropin. That this inhibition was due to suppressed PG formation is supported by successful inhibition of ovulation following treatment with PG antisera.

Follicles from superovulated mice demonstrated identical preovulatory morphology whether or not the indomethacin vehicle was administered. The apical wall underwent marked dissociation and degradation which resulted in thinning of the tissue layers. Eventually an opening appeared through which the oocyte was expressed. Germinal vesicle breakdown (GVBD) occurred in over 92% of the oocytes and the ovum developed to metaphase II. The surrounding cumulus oophorus exhibited progressive dispersion, blebbing and mucification; by 12 hours after the ovulatory gonadotropin, little contact was observed between cumulus cells and the oocyte.

Indomethacin treatment suppressed many of the morphological changes normally occurring during preovulatory follicular development. The apex failed to undergo the dramatic thinning requisite for ovulation. Maturation of the oocyte/cumulus complex was likewise inhibited; only about 30% of the oocytes demonstrated GVBD and the cumulus oophorus remained compact and tightly adherent to the oocyte. Culture experiments confirmed the observed in vivo inhibitory effect of indomethacin on the resumption of meiosis and further suggested an indirect effect on the oocyte/cumulus complex. In addition, reversal of this inhibition was achieved by treatment with exogenous PGE(,2). The results of these studies suggest a role for PGs in the morphological changes attending preovulatory development of both the follicular apex and oocyte/cumulus complex."

MPACT Scores for Stephen Michael Downs

A = 0
C = 2
A+C = 2
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-01-31 06:20:44

Advisors and Advisees Graph

Directed Graph

Students under Stephen Michael Downs

ADVISEES:
- None

COMMITTEESHIPS:
- Keith Wilson Cogdill - University of North Carolina, Chapel Hill (1998)
- Karen Michelle O'Keefe - University of North Carolina, Chapel Hill (2000)