The studies described in this thesis have been concerned with several aspects of follicular development in the mammalian ovary. Chapters 2, 3 6 4 deal with mathematical modelling of ovarian follicle dynamics in normal animals and comparisons with experimentally manipulated animals. Chapter 5 describes a novel aethod for estimating the clonal origin of the mouse ovarian follicle. In the final two chapters, the comparative physiology and anatomy of follicular numbers and sizes and the incidence of polyovular follicles are described for a number of species. The unifying theme of these studies is that they reveal patterns existing in follicular development and utllisation by detailed examination of one species, (CBA/ca mouse), and broadly by interspeci,fic comparisons (with relation to scaling). A detailed mathematical description of the follicular dynamics of virgin CBA/ca mice up to 98 days of age has been obtained by the application of compartmental modelling to differential follicle counts. The rates of follicle growth (migration) and death have been estimated for five ?stages of development (primordial to Graafian). The model predicts age changes in follicle growth and death rate, there being transitions in the parameters at 20 days second at 60 days. The parameters for normal animals have been compared with those of anilllals under two experimental conditions: 1) by unilateral ovariectomy at 4-2 days of age, which abruptly halves the numbers of ovarian follicles and alters the ratio of large : small follicles. 2) by blocking ovulation using progesterone implants. The dynamics of follicle growth were altered by both treatments in comparison with the controls. Follicles at all stages of development were affected by unilateral ovariectomy and differences may exist with time. The compensatory response by the remaining ovary was due to a combination of an increased preantral growth rate and a decrease in atresia at antral stages. Earlier stages of follicle development were affected this may have been incidental to the compensatory response. In progesterone treated animals follicles developed through to antral stages when they un~erwent atresia. The effects of treatment were observed at three levels of development: 1) The initiation of growth from the primordial pool, 2) Growth rate of small follicles and 3) deaths at larger stages of follicular development. Longer term observations indicated that these effects may not be constant. The modelling studies have looked at numerical changes in the follicle population with time but a greater understanding of the develomental biology of the follicle is required in order to explain the changes in growth and death rates observed. This problem has been tackled initially by studying the clonal origin of the follicular epithelium. The technique used is based on the principle that cells in females. are generally mosaic as a result of X-chromosome inactivation the use of X linked cell markers phospho-glycerate kinase-1 (PGK-1). Granulosa cells were found to be polyclonal in origin with the number of progenitor cells numbering 5 on average. Analysis of cumulus and mural granulosa cells showed that substantial cell mixing had occurred and cuaulus cells were generally founded by more than one clone. Finally, comparative studies have been conducted to look at scaling of follicle sizes and numbers and of polyovular follicles. Ovarian follicle and oocyte sizes were scaled according to body weight (ranging from .005-500Kg) using data from 22 species. Primordial and Graafian follicle sizes varied with body weight but closer correlations for the latter were obtained when the sum of the surface areas or volUiles for a preovulatory set were considered as opposed to the values for individual follicles. The numbers of nongrowtng follicles 1n reserve at young adult ages were correlated with maximum longevity of the species and related to body weight. The frequency of polyov~lar follicles varied 1n species studied and were most abundant 1n the domestic bitch. The overall incidence of polyovular folUcles 1n young bitches was 14 S, being reduced to 5~ 1n bitches at 7-11 years. The frequency of the various types of polyovular preantral folUcle varied inversely with the numbers of oocytes per follicle.

<p>The objective of this research was to assess ultrasound image attributes of human dominant ovarian follicles in the final stages of development during natural and oral contraceptive (OC) cycles, as well as characterize ovarian follicular and endometrial development during and after continuous versus conventional dosing schemes. We utilized sophisticated computer algorithms to elucidate an association between image attributes and physiologic status of follicles in their final stage of development. We used transvaginal ultrasonography to quantify changes in the numbers and diameters of ovarian follicles and changes in endometrial thickness and pattern during and following discontinuation of two different regimens of OC. Developmental changes in ovarian follicles and corpora lutea were correlated with serum estradiol-17â and progesterone, respectively to provide a comprehensive approach to examining ovarian and uterine function. </p><p>We reported for the first time that follicles which develop during natural and OC cycles have similar image attributes, which provides preliminary evidence that image attributes of human follicles are associated with physiologic status during the growth phase. Further research should be performed to elucidate the exact correlation between image attributes during all stages of follicular development throughout the menstrual cycle, prediction of dysfunctional follicular development (i.e., hemorrhagic anovulatory follicles) and the effects of different OC formulations on follicle development. Once the association between image attributes and various scenarios of follicular development are determined, a computer program could be developed to assess follicular health with a single ultrasound examination, obviating many ethical constraints that currently prevent large scale progress in ovarian follicular research. We further documented that continuous OC administration schemes provide greater follicular suppression than conventional dosing schemes. No dominant follicles developed during three consecutive 28 day cycles of continuous OC use, whereas eight dominant follicles developed during the same time period of conventional OC use. We interpreted these findings to mean that continuous OC dosing schemes provide a more effective contraceptive with a decreased risk of escape ovulation compared to conventional dosing schemes. Most follicles ovulated in the immediate cycle following discontinuation of OC. We suggest that the delay to fertility following cessation of OC is not due to anovulation but other yet, unknown, biological factors. </p>

<p>The objective of this research was to assess ultrasound image attributes of human dominant ovarian follicles in the final stages of development during natural and oral contraceptive (OC) cycles, as well as characterize ovarian follicular and endometrial development during and after continuous versus conventional dosing schemes. We utilized sophisticated computer algorithms to elucidate an association between image attributes and physiologic status of follicles in their final stage of development. We used transvaginal ultrasonography to quantify changes in the numbers and diameters of ovarian follicles and changes in endometrial thickness and pattern during and following discontinuation of two different regimens of OC. Developmental changes in ovarian follicles and corpora lutea were correlated with serum estradiol-17â and progesterone, respectively to provide a comprehensive approach to examining ovarian and uterine function. </p><p>We reported for the first time that follicles which develop during natural and OC cycles have similar image attributes, which provides preliminary evidence that image attributes of human follicles are associated with physiologic status during the growth phase. Further research should be performed to elucidate the exact correlation between image attributes during all stages of follicular development throughout the menstrual cycle, prediction of dysfunctional follicular development (i.e., hemorrhagic anovulatory follicles) and the effects of different OC formulations on follicle development. Once the association between image attributes and various scenarios of follicular development are determined, a computer program could be developed to assess follicular health with a single ultrasound examination, obviating many ethical constraints that currently prevent large scale progress in ovarian follicular research. We further documented that continuous OC administration schemes provide greater follicular suppression than conventional dosing schemes. No dominant follicles developed during three consecutive 28 day cycles of continuous OC use, whereas eight dominant follicles developed during the same time period of conventional OC use. We interpreted these findings to mean that continuous OC dosing schemes provide a more effective contraceptive with a decreased risk of escape ovulation compared to conventional dosing schemes. Most follicles ovulated in the immediate cycle following discontinuation of OC. We suggest that the delay to fertility following cessation of OC is not due to anovulation but other yet, unknown, biological factors. </p>

Two studies were designed to characterize the effects of a non-steroidal aromatase inhibitor, letrozole, on ovarian function in cattle. The specific objective was to test the hypothesis that letrozole will arrest dominant follicle growth resulting in emergence of a new follicular wave at a predictable interval post-treatment. In a first experiment, postpubertal beef heifers were assigned randomly to four treatment groups and given phosphate-buffered saline (controls; n=10), or letrozole at a dose of 500 (n=9), 250 (n=10), or 125 (n=10) µg/kg intravenously 4 days after follicular ablation (~2.5 days after wave emergence). In a second study, postpubertal beef heifers were assigned randomly to four treatment groups. One group received no treatment (control; n=17) and the other groups (n=9-10) were given 85 µg/kg of letrozole per day (250 µg/kg total dose), from Days 1 to 3, Days 3 to 5, or Days 5 to 7 (Day 0 = pre-treatment ovulation,) corresponding to the periods before, during and after selection of the dominant follicle, respectively. Follicular dynamics were monitored ultrasonically and blood samples were collected for endocrine assays. Follicle diameter profiles and plasma LH, FSH, and estradiol concentrations were analyzed. Additionally, during the second trial, CL diameter profiles and plasma progesterone concentrations were measured. In both studies, the diameter profile of the dominant follicle was larger in heifers treated with letrozole than in control heifers (P<0.05) and the intervals to new wave emergence and onset of regression of the extant dominant follicle were longer (P<0.05) in heifers treated with letrozole than in controls, regardless of the dose (high, medium, or low; single vs multiple) and the stage of the follicle wave in which treatments were initiated. Furthermore, during the second experiment, the mean CL diameter was larger in letrozole-treated heifers, although there were no differences in plasma progesterone concentrations between treated and control animals. The effects on dominant follicle and CL diameter profiles appeared to be the result of the significantly increased plasma LH concentrations observed in letrozole-treated animals during both treatment approaches (single vs multiple dose). Incomplete and inconsistent inhibition of estradiol production and the lack of a surge on FSH observed in both experiments may be a result of insufficient circulating levels of letrozole during the treatment period. In summary, a single or multiple dose of letrozole did not induce regression of the extant dominant follicle, nor did it directly affect FSH release. Conversely, letrozole extended the lifespan of the dominant follicle, in association with increased endogenous levels of LH, thereby delaying the next FSH surge and subsequent follicular wave emergence. Results suggest that letrozole has potential as a non-steroidal method for controlling ovarian function in cattle, but further studies are warranted to clarify dosage and timing of treatment to predictably affect follicular wave dynamics in cattle.

Two studies were designed to characterize the effects of a non-steroidal aromatase inhibitor, letrozole, on ovarian function in cattle. The specific objective was to test the hypothesis that letrozole will arrest dominant follicle growth resulting in emergence of a new follicular wave at a predictable interval post-treatment. In a first experiment, postpubertal beef heifers were assigned randomly to four treatment groups and given phosphate-buffered saline (controls; n=10), or letrozole at a dose of 500 (n=9), 250 (n=10), or 125 (n=10) µg/kg intravenously 4 days after follicular ablation (~2.5 days after wave emergence). In a second study, postpubertal beef heifers were assigned randomly to four treatment groups. One group received no treatment (control; n=17) and the other groups (n=9-10) were given 85 µg/kg of letrozole per day (250 µg/kg total dose), from Days 1 to 3, Days 3 to 5, or Days 5 to 7 (Day 0 = pre-treatment ovulation,) corresponding to the periods before, during and after selection of the dominant follicle, respectively. Follicular dynamics were monitored ultrasonically and blood samples were collected for endocrine assays. Follicle diameter profiles and plasma LH, FSH, and estradiol concentrations were analyzed. Additionally, during the second trial, CL diameter profiles and plasma progesterone concentrations were measured. In both studies, the diameter profile of the dominant follicle was larger in heifers treated with letrozole than in control heifers (P<0.05) and the intervals to new wave emergence and onset of regression of the extant dominant follicle were longer (P<0.05) in heifers treated with letrozole than in controls, regardless of the dose (high, medium, or low; single vs multiple) and the stage of the follicle wave in which treatments were initiated. Furthermore, during the second experiment, the mean CL diameter was larger in letrozole-treated heifers, although there were no differences in plasma progesterone concentrations between treated and control animals. The effects on dominant follicle and CL diameter profiles appeared to be the result of the significantly increased plasma LH concentrations observed in letrozole-treated animals during both treatment approaches (single vs multiple dose). Incomplete and inconsistent inhibition of estradiol production and the lack of a surge on FSH observed in both experiments may be a result of insufficient circulating levels of letrozole during the treatment period. In summary, a single or multiple dose of letrozole did not induce regression of the extant dominant follicle, nor did it directly affect FSH release. Conversely, letrozole extended the lifespan of the dominant follicle, in association with increased endogenous levels of LH, thereby delaying the next FSH surge and subsequent follicular wave emergence. Results suggest that letrozole has potential as a non-steroidal method for controlling ovarian function in cattle, but further studies are warranted to clarify dosage and timing of treatment to predictably affect follicular wave dynamics in cattle.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

The porcine antral follicle, which consists of an oocyte and surrounding follicular components, including theca, granulosa, and cumulus cells and follicular fluid, is an essential microenvironment for oocyte development and maturation. Investigating cellular and molecular events in the context of the whole follicle will aid in our understanding of interactions between the oocyte and the follicular components. The objective of this dissertation was to develop a novel bioluminescent imaging model to visualize and measure cellular and molecular events in living intact ovarian follicles in vitro. Bioluminescence imaging was employed to facilitate noninvasive, dynamic, and real-time transgene analysis in living intact follicles. The time courses of luciferase-luciferin reactions, effective plasmid DNA and D-luciferin doses and their combinations were determined as the first step toward developing a new real-time bioluminescence imaging model. In addition, the efficient nonviral gene delivery methods: cationic lipid mediated gene transfer (chemical) and electroporation (physical) for the living intact follicles were determined. For the cationic lipid mediated gene transfer method, the 1:3 DNA lipid ratio was optimal. It was also found that the optimal condition of electroporation (4 electric pulses with 100 ms duration at field strength of 100 V/cm) resulted in 15 times higher luciferase activity and increased granulosa cell viability over the cationic lipid mediated gene transfer method. Moreover, increased granulosa cell viability, increased follicular fluid progesterone content, and oocytes with expanded cumulus cells were observed in intact follicles transfected by electroporation at a field strength of 100 V/cm. Finally, bioluminescence imaging was applied to quantify functional and ligand-activated estrogen receptor (ER) activity within living intact follicles. The functional ERs were differentially activated during the different stages of the estrous cycle in the mature sow; the levels of functional ER activity in cultured granulosa cells and intact follicles in vitro were increased from late luteal phase to early follicular phase and then significantly decreased at late follicular phase. The methodology developed herein can be applicable to further our understanding of oocyte and follicle development and oocyte maturation.

Protocolos de sucesso para a maturação in vitro de oócitos de peixe são importantes, uma vez que é necessário para garantir uma fertilização bem sucedida, formação do zigoto, crescimento do embrião e seu completo desenvolvimento. Em algumas espécies, a eficiência deste processo ainda é muito baixa ou restrita a poucas substâncias que podem ser utilizadas. Assim, pesquisou-se a utilização de hormônios alternativos ao protocolo já existente para maturação in vitro de ovócitos de zebrafish. O objetivo foi avaliar a eficiência do extrato de hipófise de carpa (EHC), dos hormônios folículo estimulante (FSH) e luteinizante (LH) para fazer a maturação dos ovócitos estádio III de zebrafish. Os oócitos estádio III foram colocados em meio de cultivo Leibovitz modificado, suplementado com soro fetal bovino e adicionado o hormônio correspondente a seu tratamento (T1-controle; T2-16 μg/ml de EHC; T3- 32 μg/ml de EHC; T4- 48 μg/ml de EHC; T5- 64 μg/ml de EHC; T6- 80 μg/ml de EHC; T7- 0,5 μg/ml de FSH; T8- 0,5 μg/ml de LH e T9- 0,5 μg/ml de FSH e 0,5 μg/ml de LH). A taxa de maturação foi avaliada através da visualização da quebra da vesícula germinal (GVBD). Em todos os tratamentos houve maturação, embora o EHC tenha demonstrado taxas de maturação muito baixas (T2= 12,8%; T3=24,8%; T4=27%; T5=22,7%; T6=9,7%) e inferiores em relação a maior eficiência dos hormônios gonadotrópicos (T7=16%; T8=35%; T9=50%). Além disso foi possível verificar a viabilidade dos oócito através da fertilização in vitro do melhor tratamento (T9) com uma taxa de eclosão e desenvolvimento em larva de 60%. Os resultados da maturação in vitro utilizando estes indutores hormonais em oócitos estádio III de zebrafish mostraram-se promissores, e reforçam as perspectivas para o aprimoramento e uso desta técnica para produção in vitro de embriões viáveis. / Successful protocols for maturation of oocytes are important, as it is necessary for ensuring successful fertilization, zygote formation, embryo growth and full development. In some species the efficiency of in vitro maturation is still very low or is still restricted to a little amount of substances which can be used for the matter. Thus, we studied the use of alternative hormones to the existing protocol for in vitro maturation of zebrafish oocytes. The aim of this study was to evaluate the efficiency of the use of carp pituitary extract (CPE), the follicle stimulating hormone (FSH) and luteinizing hormone (LH) to oocyte maturation stage III of zebrafish. Oocytes stage III were placed in modified Leibovitz culture medium, suplemented with fetal bovine serum and added to the correnponding hormone treatment (T1-control; T2-16 g / ml of CHE; T3 32 g / ml of CHE, T4 - 48 g / ml of CHE; T5- 64 g / ml of CHE; T6- 80 g / ml of CHE; T7- 0.5 g / ml of FSH, T8 0.5 mg / ml of LH and T9- 0.5 g / ml of FSH and 0.5 mg / ml LH). The maturation rate was assessed by the germinal vesicle break down (GVBD). In all cases there was maturation, though the EHC has demonstrated fairly low maturation rate (T2= 12,8%; T3=24,8%; T4=27%; T5=22,7%; T6=9,7%) and lower in relation of the high efficiency presented by the gonadotropic hormones (T7=16%; T8=35%; T9=50%). In addition it was possible to verify the viability of the oocyte through IVF of the best treatment (T9) with a result of 60% of hatching and larvae development rate. The results of maturation in turn using this hormones in stage III oocytes of zebrafish proved promising, and enhance the prospects for improvement and use of this technique for in vitro production of viable embryos.

Thesis (M.Sc.) Uppsala : Sveriges lantbruksuniversitet.

Protocolos de sucesso para a maturação in vitro de oócitos de peixe são importantes, uma vez que é necessário para garantir uma fertilização bem sucedida, formação do zigoto, crescimento do embrião e seu completo desenvolvimento. Em algumas espécies, a eficiência deste processo ainda é muito baixa ou restrita a poucas substâncias que podem ser utilizadas. Assim, pesquisou-se a utilização de hormônios alternativos ao protocolo já existente para maturação in vitro de ovócitos de zebrafish. O objetivo foi avaliar a eficiência do extrato de hipófise de carpa (EHC), dos hormônios folículo estimulante (FSH) e luteinizante (LH) para fazer a maturação dos ovócitos estádio III de zebrafish. Os oócitos estádio III foram colocados em meio de cultivo Leibovitz modificado, suplementado com soro fetal bovino e adicionado o hormônio correspondente a seu tratamento (T1-controle; T2-16 μg/ml de EHC; T3- 32 μg/ml de EHC; T4- 48 μg/ml de EHC; T5- 64 μg/ml de EHC; T6- 80 μg/ml de EHC; T7- 0,5 μg/ml de FSH; T8- 0,5 μg/ml de LH e T9- 0,5 μg/ml de FSH e 0,5 μg/ml de LH). A taxa de maturação foi avaliada através da visualização da quebra da vesícula germinal (GVBD). Em todos os tratamentos houve maturação, embora o EHC tenha demonstrado taxas de maturação muito baixas (T2= 12,8%; T3=24,8%; T4=27%; T5=22,7%; T6=9,7%) e inferiores em relação a maior eficiência dos hormônios gonadotrópicos (T7=16%; T8=35%; T9=50%). Além disso foi possível verificar a viabilidade dos oócito através da fertilização in vitro do melhor tratamento (T9) com uma taxa de eclosão e desenvolvimento em larva de 60%. Os resultados da maturação in vitro utilizando estes indutores hormonais em oócitos estádio III de zebrafish mostraram-se promissores, e reforçam as perspectivas para o aprimoramento e uso desta técnica para produção in vitro de embriões viáveis. / Successful protocols for maturation of oocytes are important, as it is necessary for ensuring successful fertilization, zygote formation, embryo growth and full development. In some species the efficiency of in vitro maturation is still very low or is still restricted to a little amount of substances which can be used for the matter. Thus, we studied the use of alternative hormones to the existing protocol for in vitro maturation of zebrafish oocytes. The aim of this study was to evaluate the efficiency of the use of carp pituitary extract (CPE), the follicle stimulating hormone (FSH) and luteinizing hormone (LH) to oocyte maturation stage III of zebrafish. Oocytes stage III were placed in modified Leibovitz culture medium, suplemented with fetal bovine serum and added to the correnponding hormone treatment (T1-control; T2-16 g / ml of CHE; T3 32 g / ml of CHE, T4 - 48 g / ml of CHE; T5- 64 g / ml of CHE; T6- 80 g / ml of CHE; T7- 0.5 g / ml of FSH, T8 0.5 mg / ml of LH and T9- 0.5 g / ml of FSH and 0.5 mg / ml LH). The maturation rate was assessed by the germinal vesicle break down (GVBD). In all cases there was maturation, though the EHC has demonstrated fairly low maturation rate (T2= 12,8%; T3=24,8%; T4=27%; T5=22,7%; T6=9,7%) and lower in relation of the high efficiency presented by the gonadotropic hormones (T7=16%; T8=35%; T9=50%). In addition it was possible to verify the viability of the oocyte through IVF of the best treatment (T9) with a result of 60% of hatching and larvae development rate. The results of maturation in turn using this hormones in stage III oocytes of zebrafish proved promising, and enhance the prospects for improvement and use of this technique for in vitro production of viable embryos.