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The immature human ovary shows loss of abnormal follicles and increasing follicle developmental competence through childhood and adolescence.

Anderson RA, McLaughlin M, Wallace WH, Albertini DF, Telfer EE - Hum. Reprod. (2013)

Bottom Line: Follicles from pubertal ovaries showed increased growth; this was still reduced compared with follicles from adult women (P < 0.05) but oocyte growth was proportionate to follicle size.The reduced growth of isolated follicles indicates that there are true intrafollicular differences in addition to potential differences in their local environment, and that there are maturational processes occurring in the ovary through childhood and adolescence, which involve the loss of abnormal follicles, and increasing follicle developmental competence.No competing interests.

View Article: PubMed Central - PubMed

Affiliation: MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.

ABSTRACT

Study question: Do the ovarian follicles of children and adolescents differ in their morphology and in vitro growth potential from those of adults?

Summary answer: Pre-pubertal ovaries contained a high proportion of morphologically abnormal non-growing follicles, and follicles showed reduced capacity for in vitro growth.

What is known already: The pre-pubertal ovary is known to contain follicles at the early growing stages. How this changes over childhood and through puberty is unknown, and there are no previous data on the in vitro growth potential of follicles from pre-pubertal and pubertal girls.

Study design, size, duration: Ovarian biopsies from five pre-pubertal and seven pubertal girls and 19 adult women were analysed histologically, cultured in vitro for 6 days, with growing follicles then isolated and cultured for a further 6 days.

Participants/materials, setting, methods: Ovarian biopsies were obtained from girls undergoing ovarian tissue cryopreservation for fertility preservation, and compared with biopsies from adult women. Follicle stage and morphology were classified. After 6 days in culture, follicle growth initiation was assessed. The growth of isolated secondary follicles was assessed over a further 6 days, including analysis of oocyte growth.

Main results and the role of chance: Pre-pubertal ovaries contained a high proportion of abnormal non-growing follicles (19.4 versus 4.85% in pubertal ovaries; 4004 follicles analysed; P = 0.02) characterized by indistinct germinal vesicle membrane and absent nucleolus. Follicles with this abnormal morphology were not seen in the adult ovary. During 6 days culture, follicle growth initiation was observed at all ages; in pre-pubertal samples there was very little development to secondary stages, while pubertal samples showed similar growth activation to that seen in adult tissue (pubertal group: P = 0.02 versus pre-pubertal, ns versus adult). Isolated secondary follicles were cultured for a further 6 days. Those from pre-pubertal ovary showed limited growth (P < 0.05 versus both pubertal and adult follicles) and no change in oocyte diameter over that period. Follicles from pubertal ovaries showed increased growth; this was still reduced compared with follicles from adult women (P < 0.05) but oocyte growth was proportionate to follicle size.

Limitations, reasons for caution: These data derive from only a small number of ovarian biopsies, although large numbers of follicles were analysed. It is unclear whether the differences between groups are related to puberty, or just age.

Wider implications of the findings: These findings show that follicles from girls of all ages can be induced to grow in vitro, which has important implications for some patients who are at high risk of malignant contamination of their ovarian tissue. The reduced growth of isolated follicles indicates that there are true intrafollicular differences in addition to potential differences in their local environment, and that there are maturational processes occurring in the ovary through childhood and adolescence, which involve the loss of abnormal follicles, and increasing follicle developmental competence.

Study funding/competing interest(s): Funded by MRC grants G0901839 and G1100357. No competing interests.

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(A) Distribution of follicle stages (as percentage of total) in cultured ovarian tissue in pre-pubertal, pubertal and adult groups, before culture (Day 0) and after 6 days. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. (B) Follicle diameter during culture of isolated secondary follicles. Follicles were isolated from tissue after 6 days of culture, and follicle diameter was determined 2, 4 and 6 days thereafter. Blue triangles, pre-pubertal group; red squares, pubertal group; green circles: adult group (mean ± sem, n = 15, 73 and 44 respectively). *P < 0.05 versus pre-pubertal group, †P < 0.05 versus adult group. (C) Oocyte diameter of isolated secondary follicles after culture for 6 days in tissue, then a further 6 days as isolated follicles, to Day 12. Blue columns: Day 6; yellow columns, Day 12. Mean ± SEM, n = 15 and 77 follicles in pre-pubertal and pubertal groups, respectively, n = 44 follicles in adult group.*P < 0.05 versus Day 6.
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DET388F3: (A) Distribution of follicle stages (as percentage of total) in cultured ovarian tissue in pre-pubertal, pubertal and adult groups, before culture (Day 0) and after 6 days. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. (B) Follicle diameter during culture of isolated secondary follicles. Follicles were isolated from tissue after 6 days of culture, and follicle diameter was determined 2, 4 and 6 days thereafter. Blue triangles, pre-pubertal group; red squares, pubertal group; green circles: adult group (mean ± sem, n = 15, 73 and 44 respectively). *P < 0.05 versus pre-pubertal group, †P < 0.05 versus adult group. (C) Oocyte diameter of isolated secondary follicles after culture for 6 days in tissue, then a further 6 days as isolated follicles, to Day 12. Blue columns: Day 6; yellow columns, Day 12. Mean ± SEM, n = 15 and 77 follicles in pre-pubertal and pubertal groups, respectively, n = 44 follicles in adult group.*P < 0.05 versus Day 6.

Mentions: Non-growing follicles accounted for a mean of 96 and 89% of all the follicles observed in uncultured tissue in pre-pubertal and pubertal groups, respectively (2672 and 1278 follicles examined in each of the groups); these were not significantly different, and was also similar to the proportion in adult ovary (81%, n = 798 follicles examined) (Fig. 1C). After 6 days of incubation, cortical fragments were examined microscopically and the stage of follicle development categorized. A total of 1500 and 1467 follicles were analysed in the pre-pubertal and pubertal groups, respectively, and 592 in the adult group. Initiation of follicle growth was observed in all cultured biopsies. After 6 days of incubation the proportion of non-growing follicles was 73.4% in the pre-pubertal group and 66.9% in the pubertal group (both P < 0.001 versus uncultured) and 57.3% in the adult group (P < 0.001 versus uncultured; Fig. 3A). Development to the secondary stage occurred more frequently in the pubertal group with 9.1% of follicles reaching this stage at Day 6 culture (from 1.6% in uncultured tissue; P = 0.007), whereas only 2.0% of follicles were at that stage in the pre-pubertal group compared with 0% in uncultured (not significant versus uncultured; P = 0.02 versus pubertal group after 6 days; Fig. 3A). In adult tissues, 11.0% of follicles had reached the secondary stage after culture compared with 4.8% at the start (P = 0.03; Fig. 3A). Thus, pre-pubertal and pubertal samples were similar pre-culture, and while the pre-pubertal samples showed limited follicle growth activation in culture, the pubertal samples showed similar activation to that seen in adult tissue.Figure 3


The immature human ovary shows loss of abnormal follicles and increasing follicle developmental competence through childhood and adolescence.

Anderson RA, McLaughlin M, Wallace WH, Albertini DF, Telfer EE - Hum. Reprod. (2013)

(A) Distribution of follicle stages (as percentage of total) in cultured ovarian tissue in pre-pubertal, pubertal and adult groups, before culture (Day 0) and after 6 days. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. (B) Follicle diameter during culture of isolated secondary follicles. Follicles were isolated from tissue after 6 days of culture, and follicle diameter was determined 2, 4 and 6 days thereafter. Blue triangles, pre-pubertal group; red squares, pubertal group; green circles: adult group (mean ± sem, n = 15, 73 and 44 respectively). *P < 0.05 versus pre-pubertal group, †P < 0.05 versus adult group. (C) Oocyte diameter of isolated secondary follicles after culture for 6 days in tissue, then a further 6 days as isolated follicles, to Day 12. Blue columns: Day 6; yellow columns, Day 12. Mean ± SEM, n = 15 and 77 follicles in pre-pubertal and pubertal groups, respectively, n = 44 follicles in adult group.*P < 0.05 versus Day 6.
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Related In: Results  -  Collection

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DET388F3: (A) Distribution of follicle stages (as percentage of total) in cultured ovarian tissue in pre-pubertal, pubertal and adult groups, before culture (Day 0) and after 6 days. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. (B) Follicle diameter during culture of isolated secondary follicles. Follicles were isolated from tissue after 6 days of culture, and follicle diameter was determined 2, 4 and 6 days thereafter. Blue triangles, pre-pubertal group; red squares, pubertal group; green circles: adult group (mean ± sem, n = 15, 73 and 44 respectively). *P < 0.05 versus pre-pubertal group, †P < 0.05 versus adult group. (C) Oocyte diameter of isolated secondary follicles after culture for 6 days in tissue, then a further 6 days as isolated follicles, to Day 12. Blue columns: Day 6; yellow columns, Day 12. Mean ± SEM, n = 15 and 77 follicles in pre-pubertal and pubertal groups, respectively, n = 44 follicles in adult group.*P < 0.05 versus Day 6.
Mentions: Non-growing follicles accounted for a mean of 96 and 89% of all the follicles observed in uncultured tissue in pre-pubertal and pubertal groups, respectively (2672 and 1278 follicles examined in each of the groups); these were not significantly different, and was also similar to the proportion in adult ovary (81%, n = 798 follicles examined) (Fig. 1C). After 6 days of incubation, cortical fragments were examined microscopically and the stage of follicle development categorized. A total of 1500 and 1467 follicles were analysed in the pre-pubertal and pubertal groups, respectively, and 592 in the adult group. Initiation of follicle growth was observed in all cultured biopsies. After 6 days of incubation the proportion of non-growing follicles was 73.4% in the pre-pubertal group and 66.9% in the pubertal group (both P < 0.001 versus uncultured) and 57.3% in the adult group (P < 0.001 versus uncultured; Fig. 3A). Development to the secondary stage occurred more frequently in the pubertal group with 9.1% of follicles reaching this stage at Day 6 culture (from 1.6% in uncultured tissue; P = 0.007), whereas only 2.0% of follicles were at that stage in the pre-pubertal group compared with 0% in uncultured (not significant versus uncultured; P = 0.02 versus pubertal group after 6 days; Fig. 3A). In adult tissues, 11.0% of follicles had reached the secondary stage after culture compared with 4.8% at the start (P = 0.03; Fig. 3A). Thus, pre-pubertal and pubertal samples were similar pre-culture, and while the pre-pubertal samples showed limited follicle growth activation in culture, the pubertal samples showed similar activation to that seen in adult tissue.Figure 3

Bottom Line: Follicles from pubertal ovaries showed increased growth; this was still reduced compared with follicles from adult women (P < 0.05) but oocyte growth was proportionate to follicle size.The reduced growth of isolated follicles indicates that there are true intrafollicular differences in addition to potential differences in their local environment, and that there are maturational processes occurring in the ovary through childhood and adolescence, which involve the loss of abnormal follicles, and increasing follicle developmental competence.No competing interests.

View Article: PubMed Central - PubMed

Affiliation: MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.

ABSTRACT

Study question: Do the ovarian follicles of children and adolescents differ in their morphology and in vitro growth potential from those of adults?

Summary answer: Pre-pubertal ovaries contained a high proportion of morphologically abnormal non-growing follicles, and follicles showed reduced capacity for in vitro growth.

What is known already: The pre-pubertal ovary is known to contain follicles at the early growing stages. How this changes over childhood and through puberty is unknown, and there are no previous data on the in vitro growth potential of follicles from pre-pubertal and pubertal girls.

Study design, size, duration: Ovarian biopsies from five pre-pubertal and seven pubertal girls and 19 adult women were analysed histologically, cultured in vitro for 6 days, with growing follicles then isolated and cultured for a further 6 days.

Participants/materials, setting, methods: Ovarian biopsies were obtained from girls undergoing ovarian tissue cryopreservation for fertility preservation, and compared with biopsies from adult women. Follicle stage and morphology were classified. After 6 days in culture, follicle growth initiation was assessed. The growth of isolated secondary follicles was assessed over a further 6 days, including analysis of oocyte growth.

Main results and the role of chance: Pre-pubertal ovaries contained a high proportion of abnormal non-growing follicles (19.4 versus 4.85% in pubertal ovaries; 4004 follicles analysed; P = 0.02) characterized by indistinct germinal vesicle membrane and absent nucleolus. Follicles with this abnormal morphology were not seen in the adult ovary. During 6 days culture, follicle growth initiation was observed at all ages; in pre-pubertal samples there was very little development to secondary stages, while pubertal samples showed similar growth activation to that seen in adult tissue (pubertal group: P = 0.02 versus pre-pubertal, ns versus adult). Isolated secondary follicles were cultured for a further 6 days. Those from pre-pubertal ovary showed limited growth (P < 0.05 versus both pubertal and adult follicles) and no change in oocyte diameter over that period. Follicles from pubertal ovaries showed increased growth; this was still reduced compared with follicles from adult women (P < 0.05) but oocyte growth was proportionate to follicle size.

Limitations, reasons for caution: These data derive from only a small number of ovarian biopsies, although large numbers of follicles were analysed. It is unclear whether the differences between groups are related to puberty, or just age.

Wider implications of the findings: These findings show that follicles from girls of all ages can be induced to grow in vitro, which has important implications for some patients who are at high risk of malignant contamination of their ovarian tissue. The reduced growth of isolated follicles indicates that there are true intrafollicular differences in addition to potential differences in their local environment, and that there are maturational processes occurring in the ovary through childhood and adolescence, which involve the loss of abnormal follicles, and increasing follicle developmental competence.

Study funding/competing interest(s): Funded by MRC grants G0901839 and G1100357. No competing interests.

Show MeSH
Related in: MedlinePlus