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Effect of follicular components on meiotic arrest and resumption in horse oocytes.
Abstract: Two experiments were conducted to evaluate the effect of follicular components on the maintenance of meiotic arrest in horse oocytes. In Expt 1, oocytes were incubated for 24 h with follicular fluid, or with granulosa cells suspended either in medium or in follicular fluid at 25 x 10(6) cells ml-1. None of the treatments resulted in significant maintenance of the germinal vesicle stage over that of non-suppressive control. Culture with follicular fluid plus granulosa cells resulted in a significantly higher proportion of oocytes at metaphase I compared with controls. In Expt 2, oocytes were divided into those originally having compact or expanded cumuli. Oocytes were cultured with sheets of mural granulosa or sections of follicle wall, or after injection into intact dissected follicles. After incubation, half of the oocytes from each suppressive treatment were matured for 24 h. All three suppressive treatments were effective in maintaining oocytes at the germinal vesicle stage (no significant difference from control oocytes fixed directly after removal from the follicle). However, no treatment maintained normal viability of oocytes, as significantly fewer oocytes were at metaphase II after all the suppression-maturation treatments compared with the maturation control. The highest rate of post-suppression maturation was found in the mural granulosa treatment. Within this treatment, the proportion of oocytes in metaphase II was significantly higher for oocytes with expanded than for oocytes with compact cumuli (31% versus 11%, respectively; P < 0.05). Suppression by injection into an intact follicle was associated with a lack of progression to metaphase II during subsequent maturation.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1995-05-01 PubMed ID: 7636796DOI: 10.1530/jrf.0.1040149Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This study investigates the influence of different parts of the horse ovary on the early development of horse oocytes, or egg cells. The researchers discovered that none of their experimental treatments could effectively maintain the early stage of oocyte development, referred to as the “germinal vesicle” stage, but combinations of these treatments could promote progression into a later developmental stage, “metaphase I”. Though all the treatments tested could keep oocytes at the germinal vesicle stage, these cells failed to maintain viability when allowed to mature, resulting in fewer mature oocytes than expected.
Experiment 1: Effects of Follicular Fluid and Granulosa Cells on Oocyte Development
The study’s first experiment attempted to assess the impact of different components of the ovarian follicle (the functional unit of the ovary that produces oocytes) on the development of horse oocytes. These components included:
- Follicular fluid: the liquid that surrounds and nourishes the developing oocyte inside the follicle.
- Granulosa cells: cells that line the follicle and produce hormones that influence oocyte development.
The researchers discovered that none of the test conditions—incubation with follicular fluid, granulosa cells in medium, or granulosa cells in follicular fluid—could effectively maintain oocytes in the germinal vesicle stage any better than the non-suppressive control. However, combining follicular fluid and granulosa cells resulted in a significantly higher proportion of oocytes progressing to the next stage, metaphase I.
Experiment 2: Effects of Cumuli, Mural Granulosa, and Follicle Wall on Oocyte Development
The second experiment classified oocytes into two categories—those with compact cumuli and those with expanded cumuli—and investigated the impact of different follicular structures on their development. These components included:
- Mural granulosa: a layer of granulosa cells found along the follicle wall.
- Follicle wall: the tissue structure containing all the other mentioned components.
The findings indicated that all three treatments—culturing oocytes with mural granulosa or sections of follicle wall or injecting them into intact dissected follicles—were effective in keeping oocytes at the germinal vesicle stage. Nevertheless, when these oocytes were allowed to mature, a significant portion did not reach metaphase II compared to the maturation control. The highest maturation rate post-suppression was seen in the mural granulosa treatment. Moreover, within this treatment, oocytes with expanded cumuli had a significantly higher chance of reaching metaphase II than those with compact cumuli. Injecting oocytes into a complete follicle resulted in a failure to reach metaphase II during subsequent maturation.
Cite This Article
APA
Hinrichs K, Martin MG, Schmidt AL, Friedman PP.
(1995).
Effect of follicular components on meiotic arrest and resumption in horse oocytes.
J Reprod Fertil, 104(1), 149-156.
https://doi.org/10.1530/jrf.0.1040149 Publication
Researcher Affiliations
- Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA.
MeSH Terms
- Animals
- Cells, Cultured
- Female
- Follicular Fluid / metabolism
- Granulosa Cells / metabolism
- Horses / physiology
- Meiosis / physiology
- Oocytes / cytology
- Oogenesis / physiology
- Ovarian Follicle / metabolism
Grant Funding
- T35 DK07635 / NIDDK NIH HHS
Citations
This article has been cited 1 times.- Martinez de Andino EV, Brom-de-Luna JG, Canesin HS, Rader K, Resende HL, Ripley AM, Love CC, Hinrichs K. Intrafollicular oocyte transfer in the horse: effect of autologous vs. allogeneic transfer and time of administration of ovulatory stimulus before transfer. J Assist Reprod Genet 2019 Jun;36(6):1237-1250.
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