Search Results

You are looking at 21 - 30 of 334 items for

  • Abstract: Fertility preservation x
  • Abstract: cryopreservation x
  • Abstract: chemotherapy x
  • Abstract: ovary transplantation x
  • Abstract: cancer treatment x
  • Abstract: ovarian transposition x
  • Abstract: testicular transplantation x
  • Abstract: xenograft x
  • Abstract: oncofertility x
  • Abstract: sperm banking x
  • Abstract: in vitro follicle culture x
Clear All Modify Search
Free access

Xiaoqian Wang, Sally Catt, Mulyoto Pangestu and Peter Temple-Smith

Ovarian tissue cryopreservation and transplantation can be used to preserve fertility for cancer patients. In this study, we assessed the viability and function of ovarian tissue from adult mice that was cryopreserved by solid surface vitrification or traditional slow-cooling using various in vitro and in vivo techniques, including allotransplantation, in vitro oocyte maturation, embryo culture in vitro, blastocyst cryopreservation, embryo transfer, and development. The importance of cumulus cells for oocyte maturation, fertilization, and embryo development was investigated. Graft recovery, follicle survival, and oocyte retrieval was similar in control, vitrified, and slow-cooled groups. High rates of oocyte maturation, cleavage, and blastocyst formation were achieved, with no significant differences between the control, vitrified or slow-cooled ovarian tissue grafts. The presence of cumulus cells was important for oocyte maturation, fertilization, and subsequent development. Cumulus–oocyte complexes with no surrounding cumulus cells (N-COCs) or with an incomplete layer (P-COCs) had significantly lower rates of oocyte maturation and blastocyst formation than cumulus–oocyte complexes with at least one complete layer of cumulus cells (F-COCs; maturation rate: 63, 78 vs 94%; blastocyst rate: 29, 49 vs 80%). Live births were achieved using vitrified blastocysts derived from oocytes taken from vitrified and slow-cooled ovarian tissue heterotypic allografts. Successful production of healthy offspring from these vitrified blastocysts suggests that this technique should be considered as a useful stage to pause in the assisted reproduction pathway. This provides an alternative protocol for restoring fertility and offering cancer patients a better indication of their chances of pregnancy and live birth.

Free access

FH Thomas, R Leask, V Srsen, SC Riley, N Spears and EE Telfer

During ovarian folliculogenesis, ascorbic acid may be involved in collagen biosynthesis, steroidogenesis and apoptosis. The aims of this study were to determine the effects of ascorbic acid on bovine follicle development in vitro. Preantral follicles were cultured for 12 days in serum-free medium containing ascorbic acid (50 microg ml(-1)). Half of the medium was replaced every 2 days, and conditioned medium was analysed for oestradiol and matrix metalloproteinase 2 (MMP-2) and MMP-9 secretion. On day 12, cell death was assessed by TdT-mediated dUTP-biotin nick end labelling (TUNEL). In the absence of serum, there was significant (P < 0.05) follicle growth and oestradiol secretion over the 12 day culture period. Ascorbic acid had no effect on these parameters. The addition of serum from day 0 stimulated follicle growth (P < 0.05), but compromised follicle integrity. By day 12 of culture, a higher proportion of follicles remained intact in the presence of ascorbic acid in serum-free conditions (P < 0.05), and significantly (P < 0.01) less granulosa and theca cell death was observed in these follicles than in control follicles. Moreover, ascorbic acid significantly (P < 0.05) increased production of MMP-9, an enzyme involved in basement membrane remodelling. In conclusion, this culture system was capable of supporting follicle differentiation over the 12 day culture period. Furthermore, ascorbic acid maintains bovine follicle health and basement membrane remodelling in vitro.

Free access

L. D. Johnson, D. F. Albertini, L. K. McGinnis and J. D. Biggers

Changes in chromatin organization, meiotic status and the development of meiotic competence in oocytes retained within mouse ovarian follicles from day 0 to day 6 in culture were examined. The effects of exposure for 24 h to human luteinizing hormone (hLH) during the last day in culture was also determined. Preantral follicles from 22- to 24-day-old (prepubertal) mice develop antra and undergo significant growth from day 0 to day 4 in culture, after which the growth rates slow. The statistical significance of meiotic progression was examined using exact logistical regression analysis, which is particularly useful when the data are sparse and unbalanced. The transition from rimmed to unrimmed germinal vesicle stages was found to occur between day 2 and day 4 of follicle culture and was not influenced by exposure to hLH. Treatment with hLH caused a significant increase in the proportion of intrafollicular oocytes resuming meiosis. Assays of meiotic competence performed in vitro in oocytes retrieved from cultured follicles demonstrated that the transition from an unrimmed to a rimmed state is closely coincident with the acquisition and expression of meiotic competence. Forty-six per cent of competent oocytes from follicle cultures at day 3 progressed to metaphase II. These results indicate that the follicle culture system used in these studies supports the transformation of enclosed oocytes from a precompetent to a competent state and can maintain meiotic arrest for up to 6 days in culture. However, an increasing proportion of oocytes exhibit abnormal meiotic progression with continued follicle culture beyond 4 days.

Free access

Nahoko Mochida, Akiko Akatani-Hasegawa, Kayo Saka, Mai Ogino, Yoko Hosoda, Ryu Wada, Hideaki Sawai and Hiroaki Shibahara

Although the ovary has a large store of germ cells, most of them do not reach mature stages. If a culture system could be developed from early growing follicles to mature oocytes, it would be useful for biological research as well as for reproductive medicine. This study was conducted to establish a multistep culture system from isolated early growing follicles to mature oocytes using a mouse model. Early growing follicles with diameters of 60–95 μm corresponding to primary and early secondary follicles were isolated from 6-day-old mice and classified into three groups by diameter. These follicles contained oocytes with diameters of ∼45 μm and one or a few layered granulosa cells on the basal lamina. Embedding in collagen gel was followed by first-step culture. After 9-day culture, the growing follicles were transferred onto collagen-coated membrane in the second step. At day 17 of the culture series, the oocyte–granulosa cell complexes were subjected to in vitro maturation. Around 90% of the oocytes in follicles surviving at day 17 resumed second meiosis (metaphase II oocytes: 49.0–58.7%), regardless of the size when the follicle culture started. To assess developmental competence to live birth, the eggs were used for IVF and implantation in pseudopregnant mice. We successfully obtained two live offspring that produced next generations after puberty. We thus conclude that the culture system reported here was able to induce the growth of small follicles and the resultant mature oocytes were able to develop into normal mice.

Free access

Noriyuki Takahashi, Wataru Tarumi and Bunpei Ishizuka

Most of the previous studies on ovarian hyaluronan (HA) have focused on mature antral follicles or corpora lutea, but scarcely on small preantral follicles. Moreover, the origin of follicular HA is unknown. To clarify the localization of HA and its synthases in small growing follicles, involvement of HA in follicle growth, and gonadotropin regulation of HA synthase (Has) gene expression, in this study, perinatal, immature, and adult ovaries of Wistar-Imamichi rats were examined histologically and biochemically and by in vitro follicle culture. HA was detected in the extracellular matrix of granulosa and theca cell layers of primary follicles and more advanced follicles. Ovarian HA accumulation ontogenetically started in the sex cords of perinatal rats, and its primary site shifted to the intrafollicular region of primary follicles within 5 days of birth. The Has1 3 mRNAs were expressed in the ovaries of perinatal, prepubertal, and adult rats, and the expression levels of Has1 and Has2 genes were modulated during the estrous cycle in adult rats and following administration of exogenous gonadotropins in immature acyclic rats. The Has1 and Has2 mRNAs were predominantly localized in the theca and granulosa cell layers of growing follicles respectively. Treatments with chemicals known to reduce ovarian HA synthesis induced follicular atresia. More directly, the addition of Streptomyces hyaluronidase, which specifically degrades HA, induced the arrest of follicle growth in an in vitro culture system. These results indicate that gonadotropin-regulated HA synthesis is involved in normal follicle growth.

Free access

I Demeestere, J Centner, C Gervy, Y Englert and A Delbaere

Folliculogenesis is a complex process regulated by various paracrine and autocrine factors. In vitro growth systems of primordial and preantral follicles have been developed for future use of immature oocytes, as sources of fertilizable oocytes and for studying follicular growth and oocyte maturation mechanisms. Rodents were often chosen for in vitro follicular culture research and a lot of factors implicated in folliculogenesis have been identified using this model. To date, the mouse is the only species in which the whole process of follicular growth, oocyte maturation, fertilization and embryo transfer into recipient females was successfully performed. However, the efficiency of in vitro culture systems must still be considerably improved. Within the follicle, numerous events affect cell proliferation and the acquisition of oocyte developmental competency in vitro, including interactions between the follicular cells and the oocyte, and the composition of the culture medium. Effects of the acting factors depend on the stage of follicle development, the culture system used and the species. This paper reviews the action of endocrine, paracrine factors and other components of culture medium on in vitro growth of preantral follicles in rodents.

Free access

M. A. Driancourt, R. Webb and R. C. Fry

Summary. The process by which a single follicle is selected to ovulate while others regress is unknown in ewes. If the dominant follicle secretes substances that directly inhibit the growth of other follicles, the superovulatory response to the administration of exogenous gonadotrophins may be blunted. Administration of 1250 iu pregnant mares' serum gonadotrophin (PMSG) before or after the emergence of the dominant follicle in the follicular phase, or 1000 iu PMSG in the presence or absence of a large healthy or atretic follicle during the luteal phase did not affect the induced ovulatory response. Comparisons between the ovary with or without the dominant follicle did not reveal any differences in ovulatory response to PMSG. The in-vitro features (i.e. mitotic index, oestradiol and testosterone production) of follicles ipsilateral or contralateral to the dominant follicle during the early and late follicular phases were also similar.

If the dominant follicle secretes substances detrimental to the other follicles, this could be mimicked in vitro. Co-culture of small follicles with the largest follicles in a closed system did not reduce their incorporation of 3H thymidine in granulosa cells, compared with small follicles cultured alone.

These data suggest that dominance is probably not operative in sheep. The administration of 500 iu of PMSG during the midfollicular phase increased ovulation rate in Merino ewes, indicating that dominance is essentially passive in ewes and can easily be overcome by raising gonadotrophin concentration.

Keywords: follicle; ovulation; gonadotrophin; paracrine regulation; sheep

Free access

Inger B Carlsson, Mika P E Laitinen, Jennifer E Scott, Henna Louhio, Louiza Velentzis, Timo Tuuri, Johanna Aaltonen, Olli Ritvos, Robert M L Winston and Outi Hovatta

The receptor tyrosine c-Kit and its cognate ligand, c-Kit ligand (KL, stem cell factor, SCF), are involved in ovarian follicular development in several animal species. We studied the expression of KL and c-Kit using in situ hybridization and immunohistochemistry in donated human ovarian cortical tissue. The KL transcripts were expressed in granulosa cells of primary follicles, whereas the expression of c-Kit was confined to the oocyte and granulosa cells in primary and secondary follicles. We employed an ovarian organ culture using firstly serum-containing and then serum-free medium to study the effects of KL and an anti-c-Kit antibody, ACK2, on the development and survival of ovarian follicles in vitro. Culture of ovarian cortical slices for 7 days resulted in a 37% increase in the number of primary follicles and a 6% increase in secondary follicles. The proportion of viable follicles decreased in all cultures. The addition of KL (1, 10 and 100 ng/ml) into the culture media did not affect the developmental stages of the follicles or the proportion of atretic follicles. Inclusion of ACK2 (800 ng/ml) in the culture medium significantly increased the proportion of atretic follicles on days 7 (49 vs 28% in control cultures) and 14 (62 vs 38%) of culture. In conclusion, c-Kit and KL are expressed in human ovaries during follicular development. Blocking the c-Kit receptor induces follicular atresia. The KL/c-Kit signaling system is likely to control the survival of human ovarian follicles during early follicular development.

Free access

N. Crozet, M. Ahmed-Ali and M. P. Dubos

The aim of the present study was to investigate the effect of size of follicle from which goat oocytes originate on their subsequent ability to be fertilized and to undergo early embryonic development in vitro. Nonatretic follicles larger than 2 mm in diameter were dissected and distributed into three groups according to size (small: 2–3 mm; medium: 3.1–5 mm; large: > 5 mm). Cumulus–oocyte complexes were isolated from the follicles and only those with a compact multilayered cumulus were selected for in vitro maturation. After maturation, 70%, 83% and 97% of oocytes from small, medium and large follicles, respectively, were at metaphase II. After in vitro fertilization, no significant difference was observed in the cleavage rate 40 h after insemination between oocytes from small (46%) and medium (55%) follicles, and between oocytes from large follicles (69%) and ovulated oocytes (75%). After in vitro culture, significantly more embryos from small follicles arrested before or at the 8–16 cell stage (84% compared with 53%, 45% and 39% of embryos from medium and large follicles and ovulated oocytes, respectively). The proportion of morulae and blastocysts obtained was 10% and 6% from small follicles, 35% and 12% from medium follicles, 29% and 26% from large follicles and 20% and 41% from ovulated oocytes. Oocytes from small and medium follicles yielded a significantly lower proportion of hatched blastocysts (0% and 3%, respectively) than did those from large follicles and from ovulated oocytes (15% and 34%, respectively). These results indicate that developmental competence of goat oocytes is acquired progressively during follicular growth and that only a small proportion of oocytes, those isolated from large antral follicles, have the capacity to progress to the blastocyst stage following in vitro maturation, fertilization and culture.

Free access

Evelyn Telfer, C. Torrance and R. G. Gosden

Summary. Isolated ovarian follicles taken from 10-day-old mice and cultured in collagen gel for 5 days, in the presence or absence of serum, were transplanted under the kidney capsule of ovariectomized mice. Hosts showed vaginal opening within 5 days and cornified vaginal smears by 9 days. Follicles proceeded to Graafian stages and luteinization occurred. Ovulation was not observed and oocytes degenerated within the luteinized follicle. Theca formation was preceded by the appearance of blood vessels within the graft. In-vitro fertilisation of harvested oocytes resulted in embryos.

Keywords: preantral follicles; collagen gel; culture; in vivo; mouse