Search Results
You are looking at 1 - 10 of 29 items for
- Author: R. G. Gosden x
- Refine by access: All content x
Search for other papers by R. G. GOSDEN in
Google Scholar
PubMed
Summary.
The principal cause of reduced fertility in 10- to 12-month-old female CBA/H-T6 and CBA mice was found to be loss of embryos at the time of, or soon after, implantation. Treatment with exogenous progesterone, but not with oestradiol benzoate, increased the number of old females having implantation sites but did not increase either the average number of implantations/female or postimplantation survival to Day 10. When bovine prolactin or HCG was administered to pregnant old mice, the implantation rate was not increased. It was concluded that the function of the CL of pregnancy in old mice may have been impaired because the lutein cells were failing to respond adequately to the luteotrophic stimulus.
Search for other papers by R. G. GOSDEN in
Google Scholar
PubMed
Summary.
A total of 168 air-dried chromosome preparations of preimplantation mouse embryos were examined. The embryos were taken from CBA/H-T6 female mice of 1 to 12 months of age. The majority in all age groups were found to be diploid. The incidence of triploidembryos was independent of, and that of other hyperdiploid embryos dependent on, maternal age.
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
Summary. Although removal of one ovary from young CBA/Ca mice and CFLP mice did not reduce the overall numbers of ova shed at ovulation, the total number of live offspring delivered during the lifespan was reduced to 65% and 50%, respectively, of control values. This reduction was due to fewer and smaller litters. The capacity of intact and unilaterally ovariectomized animals to support gestation of embryos transferred from young donors was tested to determine whether premature exhaustion of uterine function had occurred as a result of embryo overloading. An effect of breeding history on embryo survival to Day 19 of pregnancy was found after unilateral transfer, the least favourable sites for survival being the primigravid horns of ageing intact and unilaterally ovariectomized mice (0% and 1% survival, respectively, in CBA/Ca mice). The proportion of embryos surviving in multiparous horns of the one-ovary animals (24%) was greater than in horns of primigravidae and less than in horns of intact multigravidae of similar age and parity (48%). A larger proportion of ova survived in young uteri than in any of these aged horns. The results suggested that the normal decline with age in breeding potential is due to decreased uterine capacity and that the rate of loss is accelerated by both repeated embryo overloading and prolonged nulliparity, probably as a result of local factors. The decidual response was reduced in older animals, although there was no clear-cut variation with parity. Ageing uteri accumulated mast cells and macrophages, but the latter were abundant only in multiparous horns and were probably related to puerperal involutionary activities. There was no evidence that these changes in cell number or response were responsible for decreased gestational potential in ageing animals.
Search for other papers by N. I. Boland in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
The aim of this investigation was to determine the influence of epidermal growth factor (EGF) on follicular growth and steroidogenesis in mice. Follicles were cultured in medium containing human recombinant EGF at concentrations of 1–20 ng ml−1. Oestradiol production was assayed immunoenzymatically, and growth was measured by recording follicle diameter daily and by analysing the total DNA content of follicles. The effect of EGF on cumulus–oocyte complexes isolated from cultured follicles was also assessed. Results showed that EGF inhibited oestradiol production in a dose-dependent manner, but had no mitogenic effect. Despite almost complete inhibition of oestradiol production at concentrations of EGF ≥ 10 ng ml−1, follicles were still able to achieve preovulatory size and morphology, although the incidence of atresia was increased over controls. Conversely, at a concentration of only 1 ng EGF ml−1, a significantly greater number of follicles reached the Graafian stage compared with control follicles. Cumulus expansion and meiotic maturation by isolated cumulus–oocyte complexes from cultured follicles was dramatically stimulated in the presence of EGF and FSH, but not by FSH alone. These findings suggest that EGF may have a modulatory effect on oestradiol production in vivo, and that follicular growth and differentiation may be uncoupled from steroidogenesis. Finally, ovulatory changes in the cumulus–oocyte complex may require the presence of this factor.
Search for other papers by N. I. Boland in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
Analysis of chimaeric mouse ovaries using DNA in situ hybridization was undertaken to (i) investigate the morphogenesis of follicular cell clonal expansion, (ii) evaluate whether the different cell populations within the ovary are derived from the same or unrelated progenitor cells and (iii) estimate the number of progenitor cells giving rise to the different types of ovarian cell. Chimaeras were produced by aggregation of eight-cell morulae from normal mice and those transgenic for the β-globin gene. Chimaeric blastocysts were transferred to pseudopregnant hosts and the ovaries of resultant adult offspring were prepared for in situ hybridization using a digoxigenin-labelled cDNA probe to the β-globin gene. Results showed that follicles are constructed by the non-random, radial proliferation of granulosa cell clones, which form long, thin, unbranched columns across the follicle wall. Qualitative and quantitative studies revealed that both peripheral and central granulosa cells are derived from the same progenitor cells. Phenotypic differences may therefore be due to positional cues within the follicle rather than being cell lineage dependent. It is suggested that granulosa cells and germinal epithelium may be partly derived from the same progenitor cells and that theca externa is probably derived from interstitial tissue. However, results from this study did not support the contention that theca interna and theca externa–interstitial tissue have the same origin, and it is suggested that the former cell type may exist in an undifferentiated state from early stages of follicle development. Furthermore, granulosa and germinal epithelium appear to be derived from different progenitor cells from either theca interna or theca externa–interstitial cells. Evidently, all types of ovarian cell, including the somatic cells of individual follicles, are derived from more than one progenitor cell.
Search for other papers by Evelyn Telfer in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
Summary. The incidence of polyovular types in the growing follicle population was estimated using quantitative cytology. Of 15 species studied, polyovular follicles were recorded in the following species and in ascending order of abundance: rabbits, rhesus monkeys, humans, cats, dogs. The incidence in bitches was 14% in animals aged 1–2 years but only 5% at 7–11 years old. The frequency of the various types of polyovular preantral follicle varied inversely with the numbers of oocytes per follicle and the probability of finding a follicle with more than 5 oocytes was remote. In young ovaries the frequency was constant in the early stages of growth but decreased in the largest preantral stage. The pattern in ageing ovaries was, by contrast, one of declining frequency such that few if any polyovular types completed development. The ovary of the ageing bitch was also characterized by a higher incidence of degenerating follicles and a much smaller pool of primordial stages. Polyovular follicles were larger than uniovular types at comparable stages which were defined by the number of granulosa cell layers. Their oocytes were smaller but the overall ooplasmic mass was increased with a corresponding increase in the mass of granulosa cells.
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
Search for other papers by N. Brown in
Google Scholar
PubMed
Search for other papers by Kay Grant in
Google Scholar
PubMed
Summary. In a histological survey of 19 mammalian species, Call–Exner bodies of conventional size and appearance were found in only 5, namely, human, rhesus monkey, rabbit, guinea-pig and sheep. Rabbit ovaries were used for characterizing these bodies using quantitative histochemistry, lectin binding and electron microscopy. Call–Exner bodies were topographically distinct lacunae of the extracellular space probably containing hyaluronic acid with proteoglycan complexes. The staining characteristics of the antrum and Call–Exner bodies were generally similar. However, in contrast to the antrum, the smaller lacunae contained suspended filaments with a distinctive peripheral membrane upon which a rosette of granulosa cells was resting. The membrane and narrow intercellular clefts probably prevent much exchange of large glycosaminoglycan complexes with the antrum. The origin and significance of Call–Exner bodies require further study, but it is clear that they are associated with secretion rather than with necrosis as sometimes suggested.
Keywords: Call–Exner bodies; glycosaminoglycans; Graafian follicle; granulosa cell; lectin; rabbit
Search for other papers by C. Torrance in
Google Scholar
PubMed
Search for other papers by Evelyn Telfer in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
Summary. Follicles were isolated from the ovaries of 10-day-old C57BL6/CBA F1 hybrids by mechanical and enzymic treatment, embedded in a collagen-gel matrix to maintain the 3 dimensional integrity of the follicle and cultured for up to 14 days. Gels were removed at various times during the culture period and prepared for histology. Follicles grew from unilaminar to multilaminar stages within 6 days of the culture period. A more detailed assessment of growth by counting follicles at different stages and measuring oocyte and follicle diameters showed that follicle growth was maintained for up to 14 days in culture. Initially the proportion of unhealthy follicles was high but this declined after 6 days in culture.
Keywords: pre-antral follicles; collagen gel; culture; mouse
Search for other papers by Evelyn Telfer in
Google Scholar
PubMed
Search for other papers by C. Torrance in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
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
Search for other papers by H. Newton in
Google Scholar
PubMed
Search for other papers by H. Picton in
Google Scholar
PubMed
Search for other papers by R. G. Gosden in
Google Scholar
PubMed
A culture system has been designed in which enzymatically isolated oocyte–granulosa cell complexes from fresh and frozen–thawed ovine ovarian tissue can be grown to antral size in vitro. Oocyte–granulosa complexes ranging from 100 to 240 μm in diameter were dissected from stromal tissue and grown individually in serum-free medium for 30 days. Complexes < 190 pm generally excluded their oocytes or lost three-dimensional structure early in the culture period. In contrast, complexes isolated from fresh or frozen–thawed tissue and measuring 190–240 μm on the day of isolation formed antral cavities in 25 ± 9% and 18 ± 6% (mean ± sem) of cases, respectively. The effect of gonadotrophin supplementation to the culture medium was tested on frozen–thawed oocyte–granulosa cell complexes only. In cultures supplemented with both FSH and LH or FSH alone, there was no significant difference in the number of oocyte–granulosa cell complexes that formed antral cavities (18 ± 7%). However, antrum formation was significantly less frequent in cultures lacking gonadotrophin stimulation (7 ± 4%). All oocyte–granulosa cell complexes maintained a three-dimensional structure throughout culture and developed a functional P450 aromatase enzyme complex, as revealed by the induction of oestradiol production during 8 days of culture after antrum formation in serum-free medium containing testosterone. Oocytes recovered after 30 days of culture were viable and had increased in diameter from 78 ± 2 μm on the day of isolation, to 131 ± 3 pm at the end of culture. These results show that oocyte–granulosa cell complexes isolated from cryopreserved ovarian tissue can be grown to antral size in vitro with similar efficiency to those isolated from fresh tissue.
