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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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Related in: MedlinePlus

(A) Relationship between follicle number (per mm3 of tissue) and age. (B) Confocal image of ovarian cortex from a 3-year-old girl immunostained for acetylated tubulin (green) and f-actin (using phalloidin: red). (C) Distribution of follicle classes (as percentage of total) in ovarian tissue from pre-pubertal and pubertal girls, and adults. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. A total of 2672, 1278 and 798 follicles are classified in the three age groups, respectively.
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DET388F1: (A) Relationship between follicle number (per mm3 of tissue) and age. (B) Confocal image of ovarian cortex from a 3-year-old girl immunostained for acetylated tubulin (green) and f-actin (using phalloidin: red). (C) Distribution of follicle classes (as percentage of total) in ovarian tissue from pre-pubertal and pubertal girls, and adults. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. A total of 2672, 1278 and 798 follicles are classified in the three age groups, respectively.

Mentions: To determine the number and developmental stage of follicles in ovarian cortical tissue from children and teenagers, 31 fragments of tissue (2–3 per patient) were fixed fresh or post-thawing and processed for histological examination. A total of 4004 follicles were analysed in uncultured ovarian tissue. Follicle number was much higher in the three youngest girls, at 201–413/mm3, whereas it ranged from 9 to 46/mm3 in the remainder (Fig. 1A). Using whole mount confocal microscopy, it was apparent that the great majority of follicles in uncultured tissue were confined to a region subtending the tunica albuginea, recognizable because of the lower cell density and absence of nerve fibres (Fig. 1B). Most follicles appeared to be of a uniform diameter and non-growing, and embedded in an actin-rich dense stroma. Notably, the acetylated tubulin labelling not only rendered the nerve fibre network but also labelled the follicles themselves. Additionally, the pattern of phalloidin staining showed a dense layer of f-actin at the outer limits of follicles. While a small number of secondary follicles were observed in tissue from the pubertal group, none were found in the pre-pubertal group (Fig. 1C).Figure 1


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) Relationship between follicle number (per mm3 of tissue) and age. (B) Confocal image of ovarian cortex from a 3-year-old girl immunostained for acetylated tubulin (green) and f-actin (using phalloidin: red). (C) Distribution of follicle classes (as percentage of total) in ovarian tissue from pre-pubertal and pubertal girls, and adults. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. A total of 2672, 1278 and 798 follicles are classified in the three age groups, respectively.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3860895&req=5

DET388F1: (A) Relationship between follicle number (per mm3 of tissue) and age. (B) Confocal image of ovarian cortex from a 3-year-old girl immunostained for acetylated tubulin (green) and f-actin (using phalloidin: red). (C) Distribution of follicle classes (as percentage of total) in ovarian tissue from pre-pubertal and pubertal girls, and adults. Blue: non-growing follicles; red: primary follicles; green: secondary follicles. A total of 2672, 1278 and 798 follicles are classified in the three age groups, respectively.
Mentions: To determine the number and developmental stage of follicles in ovarian cortical tissue from children and teenagers, 31 fragments of tissue (2–3 per patient) were fixed fresh or post-thawing and processed for histological examination. A total of 4004 follicles were analysed in uncultured ovarian tissue. Follicle number was much higher in the three youngest girls, at 201–413/mm3, whereas it ranged from 9 to 46/mm3 in the remainder (Fig. 1A). Using whole mount confocal microscopy, it was apparent that the great majority of follicles in uncultured tissue were confined to a region subtending the tunica albuginea, recognizable because of the lower cell density and absence of nerve fibres (Fig. 1B). Most follicles appeared to be of a uniform diameter and non-growing, and embedded in an actin-rich dense stroma. Notably, the acetylated tubulin labelling not only rendered the nerve fibre network but also labelled the follicles themselves. Additionally, the pattern of phalloidin staining showed a dense layer of f-actin at the outer limits of follicles. While a small number of secondary follicles were observed in tissue from the pubertal group, none were found in the pre-pubertal group (Fig. 1C).Figure 1

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