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Regulation of oocyte microvilli development in the baboon fetal ovary by estrogen.
Endocrinology. 2004 Feb; 145(2):959-66.E

Abstract

We recently showed that the number of primordial follicles was reduced by 50% in ovaries of near-term fetal baboons deprived of estrogen in utero and restored to normal in animals supplemented with estrogen. Oocytes are avascular and rely on surrounding granulosa cells for nutrients, a process facilitated by microvilli on the oocyte surface. However, our understanding of oocyte microvillus development in the primate fetal ovary is incomplete. Thus, we determined whether estrogen regulates formation of oocyte microvilli in utero. Fetal ovaries were obtained on d 165 gestation (term = d 184) from baboons untreated (n = 3) or treated on d 100-165 with aromatase inhibitor CGS 20267 (estrogen suppressed by 95%; n = 5) or CGS 20267 and estradiol (n = 4). Follicles with intact (homogeneous cytoplasm) or nonintact (cytoplasm vacuolated) oocytes were quantified and the number/height of oocyte microvilli determined by electron microscopy. In untreated baboons, the mean (+/-se) number of follicles/0.08 mm(2) with an intact oocyte (11.5 +/- 0.5) was decreased (P < 0.05) by 70% in fetal ovaries of estrogen-suppressed baboons (3.4 +/- 0.2) and restored (P < 0.05) by CGS 20267 and estradiol (11.2 +/- 1.2). In estrogen-deprived fetuses, the number of microvilli/intact oocyte (23 +/- 3) was 56% lower (P < 0.01) than normal (52 +/- 5) and restored by CGS 20267 and estrogen (62 +/- 4). Moreover, in intact oocytes of estrogen-suppressed baboons, height (nm) of microvilli (105 +/- 11) was 54-62% lower (P < 0.01) than in intact oocytes of fetal ovaries of untreated (228 +/- 13) or estrogen-treated (274 +/- 17) baboons. In estrogen-replete baboons, the number of microvilli in intact oocytes was 2-fold greater (P < 0.01) than in nonintact oocytes. However, in estrogen-deprived baboons, no microvilli were detected in nonintact oocytes and the number of microvilli in intact oocytes was similar to that in nonintact oocytes of untreated fetuses. We conclude that development of microvilli in oocytes of primordial follicles in the primate fetal ovary is regulated by estrogen. Collectively, these results and those of our previous studies indicate that estrogen regulates fetal ovarian folliculogenesis and development of follicles with oocytes composed of microvilli critical for nutrient uptake and presumably long-term survival.

Authors+Show Affiliations

Department of Physiological Sciences, Eastern Virginia Medical School, P.O. Box 1980, Norfolk, VA 23501-1980, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

14592953

Citation

Zachos, Nicholas C., et al. "Regulation of Oocyte Microvilli Development in the Baboon Fetal Ovary By Estrogen." Endocrinology, vol. 145, no. 2, 2004, pp. 959-66.
Zachos NC, Billiar RB, Albrecht ED, et al. Regulation of oocyte microvilli development in the baboon fetal ovary by estrogen. Endocrinology. 2004;145(2):959-66.
Zachos, N. C., Billiar, R. B., Albrecht, E. D., & Pepe, G. J. (2004). Regulation of oocyte microvilli development in the baboon fetal ovary by estrogen. Endocrinology, 145(2), 959-66.
Zachos NC, et al. Regulation of Oocyte Microvilli Development in the Baboon Fetal Ovary By Estrogen. Endocrinology. 2004;145(2):959-66. PubMed PMID: 14592953.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulation of oocyte microvilli development in the baboon fetal ovary by estrogen. AU - Zachos,Nicholas C, AU - Billiar,Reinhart B, AU - Albrecht,Eugene D, AU - Pepe,Gerald J, Y1 - 2003/10/30/ PY - 2003/11/1/pubmed PY - 2004/2/26/medline PY - 2003/11/1/entrez SP - 959 EP - 66 JF - Endocrinology JO - Endocrinology VL - 145 IS - 2 N2 - We recently showed that the number of primordial follicles was reduced by 50% in ovaries of near-term fetal baboons deprived of estrogen in utero and restored to normal in animals supplemented with estrogen. Oocytes are avascular and rely on surrounding granulosa cells for nutrients, a process facilitated by microvilli on the oocyte surface. However, our understanding of oocyte microvillus development in the primate fetal ovary is incomplete. Thus, we determined whether estrogen regulates formation of oocyte microvilli in utero. Fetal ovaries were obtained on d 165 gestation (term = d 184) from baboons untreated (n = 3) or treated on d 100-165 with aromatase inhibitor CGS 20267 (estrogen suppressed by 95%; n = 5) or CGS 20267 and estradiol (n = 4). Follicles with intact (homogeneous cytoplasm) or nonintact (cytoplasm vacuolated) oocytes were quantified and the number/height of oocyte microvilli determined by electron microscopy. In untreated baboons, the mean (+/-se) number of follicles/0.08 mm(2) with an intact oocyte (11.5 +/- 0.5) was decreased (P < 0.05) by 70% in fetal ovaries of estrogen-suppressed baboons (3.4 +/- 0.2) and restored (P < 0.05) by CGS 20267 and estradiol (11.2 +/- 1.2). In estrogen-deprived fetuses, the number of microvilli/intact oocyte (23 +/- 3) was 56% lower (P < 0.01) than normal (52 +/- 5) and restored by CGS 20267 and estrogen (62 +/- 4). Moreover, in intact oocytes of estrogen-suppressed baboons, height (nm) of microvilli (105 +/- 11) was 54-62% lower (P < 0.01) than in intact oocytes of fetal ovaries of untreated (228 +/- 13) or estrogen-treated (274 +/- 17) baboons. In estrogen-replete baboons, the number of microvilli in intact oocytes was 2-fold greater (P < 0.01) than in nonintact oocytes. However, in estrogen-deprived baboons, no microvilli were detected in nonintact oocytes and the number of microvilli in intact oocytes was similar to that in nonintact oocytes of untreated fetuses. We conclude that development of microvilli in oocytes of primordial follicles in the primate fetal ovary is regulated by estrogen. Collectively, these results and those of our previous studies indicate that estrogen regulates fetal ovarian folliculogenesis and development of follicles with oocytes composed of microvilli critical for nutrient uptake and presumably long-term survival. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/14592953/Regulation_of_oocyte_microvilli_development_in_the_baboon_fetal_ovary_by_estrogen_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/en.2003-1078 DB - PRIME DP - Unbound Medicine ER -