Advancing the health and well-being of animals and people

Fellow: Kristen Roosa
Mentor: Ned Place

Department of Population Medicine and Diagnostic Sciences
Contact Information: Email:; Phone: 607-253-3796
Sponsor: Sigma Xi
Grant Number: G20111015157499
Title: In vitro Analysis of Seasonal Differences in Ovarian Primordial Follicle Recruitment Rate
Annual Direct Cost: $400
Project Period: 01/01/2012-12/31/2012

DESCRIPTION (provided by applicant): The factors that modulate the recruitment of non-growing (primordial) ovarian follicles into the growing pool are poorly understood.  Recruitment is a non-reversible process that ends in follicular atresia in the majority of follicles, though a select few progress to ovulation. Recruitment rate is directly related to reproductive senescence, as exhaustion of primordial follicles results in the end of the female reproductive lifespan, i.e. menopause in women.  Our lab’s investigations of female reproductive aging in the Siberian hamster suggest that primordial follicle recruitment is modulated by day length. Females raised in short days (SD) retain significantly more primordial follicles in old age than females in long days, consistent with inhibited primordial follicle recruitment. This study will use whole ovary culture to determine if day length indeed modulates primordial follicle recruitment rate and if SD is associated with inhibited recruitment. When placed in culture at post natal day 6 (PND6), the Siberian hamster ovary is dominated by primordial follicles. Two days in culture results in spontaneous primordial follicle recruitment into the growing pool. To test the hypothesis that SD inhibits recruitment, PND6 ovaries will be co-cultured with ovaries from adults raised in SD.  After culture both primordial and growing follicles will be counted as a representation of follicular recruitment.  It is expected that neonatal ovaries co-cultured with adult SD ovaries will have fewer growing follicles and more primordial follicles than controls, indicating inhibited recruitment.