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Different Reproductive Stages (different + reproductive_stage)
Selected AbstractsHistology, histochemistry and morphometry of the ovary of the adult plains viscacha (Lagostomus maximus) in different reproductive stagesACTA ZOOLOGICA, Issue 4 2009Mirta Alicia Flamini Abstract Lagostomus maximus is a South American Hystricognathi rodent whose reproductive behaviour shows characteristics unusual for mammals, such as polyovulation (200,800 oocytes) and a high rate of embryo mortality. Thirty-six mature females captured in the province of Buenos Aires showed different physiological reproductive stages. Most of them presented a postpartum oestrus in August,September. This characteristic is different from that reported in other geographical areas. The stages considered were: anoestrus, follicular phase, early pregnancy and late pregnancy. The ovaries were light-pink and smooth and presented a tortuous cord-like aspect. Many primordial follicles were found in all the females studied. Follicles in different states of maturation and primary and accessory corpora lutea were observed in the cortex. These structures were smaller than those present in other related species. Follicles did not project into the surface of the organ. Calcified follicles of diverse size were found in all the ovaries. Atretic follicles were found in all the stages analysed. Interstitial tissue surrounding the follicles and the corpora lutea was also observed. The number and proportion of different cortical structures varied in the physiological stages analysed. The ovaries of the viscacha have differential characteristics in comparison to other Hystricognathi, some of them related to polyovulation. [source] Stress-induced dynamic adjustments of reproduction differentially affect fitness components of a semi-arid plantJOURNAL OF ECOLOGY, Issue 1 2008Cristina F. Aragón Summary 1Summer drought stress is considered the primary constraint to plant performance in Mediterranean ecosystems. However, little is known about the implications of summer stress for plant reproduction under real field conditions and, particularly, for the regulatory mechanisms of maternal investment in reproduction. 2The relationship between plant physiological status at different reproductive stages over the course of the summer drought period and final reproductive output was modelled in the Mediterranean semi-arid specialist Helianthemum squamatum. 3Plant physiological status, assessed by the chlorophyll fluorescence-based parameter Fv/Fm, and soil moisture content beneath each plant, were determined in the field at five key phenological moments in a total of 88 plants. We used Generalized Linear Mixed Models to evaluate the effect of plant physiological status at those different dates on several components of reproduction (number of flowers and seeds per plant, fruit-set and intra-fruit seed abortion). We included soil moisture as an additional predictor to statistically control its potential effect on reproduction. 4Fv/Fm measured at midday was a significant predictor of reproductive output, but its significance varied over time and with the specific reproductive response variable. Fv/Fm measured at the onset of flowering was positively related to the number of flowers and seeds per plant, whereas Fv/Fm at the fruiting peak positively affected fruit-set. Soil moisture content was only significant when measured before flowering, being positively related to total flowers and seeds. The effect of stress on reproductive output acted either at an early stage of the reproductive season, by varying the number of flowers produced and seed primordia initiated, or at a later stage, by adjusting the number or ripe fruits. 5Synthesis. Our results show a direct relationship between physiological status and reproduction, and highlight the importance of the timing of stress for reproductive success. They also show that small departures from the physiological optimum at specific reproductive stages may cause significant decreases in the reproductive output. We suggest that the dynamic adjustment of reproduction in response to stress is adaptive in fluctuating and unpredictable Mediterranean semi-arid environments, where an adequate temporal distribution of maternal resources determines the species' ability to withstand severe environmental conditions. [source] Effects of thiol compounds on in vitro maturation of canine oocytes collected from different reproductive stagesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2007Mohammad Shamim Hossein Abstract Various thiol compounds are known to improve cytoplasmic and/or nuclear maturation of oocytes in vitro. The present study examined the effects of two thiol compounds, cysteine (0.1, 0.5, and 1.0 mM) and cysteamine (50, 100, and 200 µM), on cytoplasmic and nuclear maturation of canine oocytes. Oocytes collected from different reproductive stages were cultured in TCM-199 supplemented with 10% fetal bovine serum, 2.2 mg/ml sodium carbonate, 2.0 µg/ml estrogen, 0.5 µg/ml FSH, 0.03 IU/ml hCG, and 1% penicillin,streptomycin solution for 72 h. Data were analyzed by two-way ANOVA after arcscine transformation and protected by Bonferroni post hoc test. The effects of cysteine and cysteamine on canine IVM were varied depending on the reproductive stage of oocyte donor bitches. In the follicular stage, significantly more oocytes reached the metaphase II (M II) stage when cultured with 0.5 or 1.0 mM cysteine (16.7% and 16.9%, respectively) compared to the control (6.2%). In the follicular stage, cysteamine increased oocyte maturation rate upto the M II stage (15.1% to 17.0%) compared to the control (4.4%). Both the 0.5 mM cysteine and 100 µM cysteamine, alone or together, increased the intracellular GSH level of canine oocytes compared to the control. Irrespective of reproductive stage, no further beneficial effects on nuclear or cytoplasmic maturation were observed when 0.5 mM cysteine and 100 µM cysteamine were supplemented together. In conclusion, addition of 0.5 mM cysteine and 100 µM cysteamine to the maturation medium improved IVM of canine oocytes. Mol. Reprod. Dev. 74: 1213,1220, 2007. © 2007 Wiley-Liss, Inc. [source] Anatomicohistological Characteristics of the Female Genital Organs of the White-lipped Peccary (Tayassu pecari) in the Peruvian AmazonANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2009P. Mayor Summary This study examined the anatomical and histological characteristics of the genital organs of the female white-lipped peccary in the wild in different reproductive stages, collected by rural hunters in the North-eastern Peruvian Amazon. Mean ovulation rate was 2.12 ± 0.83 follicles and litter size was 1.78 ± 0.41 embryos or fetuses per pregnant female, resulting in a low rate of reproductive wastage, averaging 0.33 ± 0.66 (16.04%) oocytes or embryos per pregnancy. The ovulation rate and the anatomical performance of the uterus could limit the prolificacy of this species. Females in follicular phase showed follicular waves suggesting the synchronous growth of a cohort of follicles. Different uterine and vaginal epithelium features changed in accordance with the reproductive state of the female. Pregnant females and females in the luteal phase presented a significant proliferation of endometrial uterine glands, characterized by hyperplasia and branching of endometrial glands, and increase in the proportion of cervical epithelial cells with periodic acid-schiff (PAS)-positive granules compared with that in females in the follicular phase. Females in the follicular phase showed a more developed vaginal epithelium (in thickness and in layer composition) than females in the luteal phase and pregnant females. [source] | ||||||||||