Since both reproduction and immunocompetence are costly, the negative reciprocal relationships between these functions were found in many species. Due to reproductive immunosuppression, some fraction of seasonally breeding populations of small mammals reproduces in the first breeding season, while others reproduce in the next one. Elevation of breeding efforts under the increased risk of mortality and the reproductive delay until recovery are the polar variants of mating behavior of parasitized individuals. However the parasite-induced changes of odor, visual or acoustic signals limit the mating success of the infected hosts. The direct influence of the immune system, regularly activated by infections, to chemicals signals can be answer to the question: why these signals are honest? Decrease of a strange infection risk by kin breeding can be a satisfactory strategy of an isolated population. Nevertheless, many species follow the inbreeding avoidance strategy, where the major histocompatibility complex (MHC) genes play key role in kin recognition. The advantage of MHC heterozygosity was found at the all steps of the breeding cycle; including mating choice, fertilization, pre- and postnatal development. So, the relationships between immune system and neuroendocrine regulation of behavior give proximate explanations of the evolutionary stable strategies of breeding behavior.
The hatching ability was evaluated in diploid parthenogenetic mouse blastocysts based on the hatching rate, the embryonic contraction, the ultrastructure of the zona pellucida, and the activity of trypsin-like proteinase. The hatching rate of parthenogenetic blastocysts was 24.7% (87/350), which was significantly lower than 48.6% (184/383) in control blastocysts developed from fertilized 1-cell embryos (fertilized blastocysts). During observation for 32 h after blastocoel formation, strong contractions (20% or more volume reduction) occurred more frequently in parthenogenetic blastocysts (2.4 times) than in fertilized blastocysts (1.4 times, P<0.01). The lengths of time needed for re-expansion following both weak (less than 20% volume reduction) and strong contractions were significantly longer in parthenogenetic blastocysts (147.7 and 345.0 min) than in fertilized blastocysts (107.7 and 242.6 min). The zona pellucida showed a dense and homogeneous microgranular appearance in both parthenogenetic and fertilized blastocysts, while the zona pellucida of parthenogenetic blastocysts showed a few cracks in the outer surface. A similar morphological change was also observed in fertilized blastocysts developed following ethanol treatment, suggesting that the zona crack may be induced by ethanol treatment. The thickness of the zona pellucida and the activity of trypsin-like proteinase did not differ between parthenogenetic and fertilized blastocysts. These results suggest that the lower rate of hatching in parthenogenetic blastocysts might be due to the large number of strong contractions that require longer duration for re-expansion rather than changes in the structure of the zona pellucida or the activity of trypsin-like proteinase of the embryos.
This was a study on the developmental ability of porcine embryos reconstructed by microinjection of a nucleus of cultured (non-starving culture) cumulus cells directly into the cytoplasm of oocytes matured and enucleated in vitro. Cumulus-oocyte complexes (COCs) derived from slaughterhouse ovaries were matured for 22 h in a modified NCSU23 (mNCSU23) medium supplemented with pFF, cysteine, PMSG, hCG and EGF, and then for another 22 h in the same medium without the hormones. In the meantime, cumulus cells were freed from some COCs and cultured in MEM supplemented with 10% FCS. After 44 h of culture, the smaller cumulus cells (10-12 μm) were injected directly into the cystoplasm of enucleated oocytes. The cell membrane of cumulus cells was broken mechanically prior to the injection. After incubation for 30 min in mNCSU23 supplemented with 4 mg/ml BSA and 0.1 mg/ml cysteine, reconstructed oocytes were activated by exposure to 200 μM thimerosal for 10 min followed by incubation in 8 mM dithiothreitol for 30 min. Oocytes with an intact plasma membrane were then cultured in mNCSU23 supplemented with BSA. The development of reconstructed embryos and the number of nuclei in them were monitored after 48 h and 6 days of culture. As a control group, oocytes were activated parthenogenetically and cultured as described above. The percentage of cleavage in the nuclear transfer (NT) group after 48 h of activation was significantly lower than that in the control group (36.4% vs 83.7%, P<0.05), but the rates of blastocyst were similar in the NT and control groups (5.5% vs 10.9%). The mean numbers of cells in a blastocyst were 19.3 and 30.3 for NT and control groups, respectively. These results indicate that the reconstructed embryos prepared in the system described can develop to the blastocyst stage.
To clarify the endocrinological characteristics of bovine gonadal hypoplasia (XY female), peripheral FSH, LH, inhibin, estradiol-17β (E2), progesterone (P) and testosterone (T) levels were measured before and after the administration of eCG, hCG and GnRH-A in the 3 bovine XY females without the Sry gene. Before the administration of hormonal drugs, the concentrations of FSH and LH were higher than in adult bulls, cows in the luteal phase and castrated bulls. On the other hand, the concentrations of inhibin and E2 were lower than those observed in the follicular phase during the estrous cycle. Concentrations of P and T were much lower than those observed in the luteal phase during the estrous cycle and in bulls. Gonads of our XY females did not respond to eCG or hCG stimulation, whereas the pituitary was highly responsive to GnRH-A in LH secretion.
The influence of allogenic stimulation on pregnancy and the development of progeny was studied in BALB/cLac female mice that were injected with C57BL/6J male (allogenic) red blood cells (AB) on the second day after intrastrain mating. On the 4th day of pregnancy AB-treated females had higher levels of plasma progesterone than syngenic blood (SB) treated females and controls (saline-treated). Administration of allogenic erythrocytes also stimulated embryo development and improved maternal behaviour. On the day of birth the incidence of new-born rejection was much lower in AB-treated mice than in SB-treated mice A battery of physiological and behavioural tests were used to assess the adaptive features of BALB/cLac males born to females injected with AB, SB or saline. These offspring groups did not differ in parameters of maximum aerobic performance, cold resistance or humoral immune response. At the same time, offspring of antigenically challenged mothers had less adrenocortical and behavioural responses to emotional stressors than offspring of SB and saline treated females. AB males also had higher mating success than other male groups.
In the present study, in order to investigate the incidence time of abnormal corpus luteum (CL) in superovulated ewes, CL formation was observed and plasma progesterone (P4) and estradiol-17β(E2) profiles were investigated during the non-breeding and breeding seasons in three breeds of ewes. The ewes were treated with a fluorogesterone acetate (FGA) sponge for 12 days, and a single injection of 20 mg pFSH on Day - 2 and 500 IU eCG on Day - 1 (FGA sponge removal: Day 0), for estrous synchronization and superovulation. All ewes were given an injection of 100 μg gonadotropin releasing hormone analogue (GnRH analogue) at estrous detection and inseminated with frozen-thawed semen by laparoscope on a fixed-time basis (32-36 h after FGA sponge removal). On Day 6.5, the ewes were laparotomized for ovarian response and embryo recovery. Blood was taken from all ewes on Days 0 to 6.5, and the plasma P4 and E2 concentrations were measured by emzyme immunoassay (EIA). According to the ovarian responses on Day 6.5, the ewes were divided into Group N (only normal CL; n=21), Group A (only abnormal CL; n=7) and Group M (both normal and abnormal CL; n=3). The mean P4 profile in Group N continued to rise during the period of blood sampling, and was significantly higher than in Group A which remained under 1 ng/ml and decreased after Days 4 to 4.5. The means E2 levels tended to be higher in Group A than in Group N. In the autumn study, the ewes with abnormal CL on Day 6.5 had already lacked in color on Day 4.5, and the number of large follicles was significantly lower in the ewes with abnormal CL than in those with only normal CL. These results indicate that the phenomenon of abnormal CL formation at 3-3.5 days after estrus is not due to premature luteal regression of functionally complete CL, but to luteal hypoplasia of incomplete CL with a short lifespan, but the cause of abnormal CL was not determined in the study.
This study was conducted to investigate the effects of ooplasm clarification, sperm tail-cutting and reduction of the polyvinylpyrrolidone (PVP) concentration in the sperm injection vehicle solution on ICSI in cattle. In vitro matured oocytes, motile spermatozoa and a piezo system were used for ICSI. In experiment 1, oocytes were centrifuged at 6,000 × g for 7 min to polarize the ooplasm lipid before ICSI. Sperm tail-cutting was carried out and the effect on ICSI was tested in experiment 2. In experiment 3, the effect of the PVP concentration in the sperm injection vehicle solution on ICSI was investigated. After ICSI, oocytes were cultured in vitro in mTALP for 15 h before fixation and observation. It was found that ooplasm clarification and sperm tail-cutting before ICSI significantly enhanced the survival rate of oocytes (92.0% vs. 67.7% and 94.8% vs. 77.3%: p<0.001, respectively) and the pronuclear formation rate (87.6% vs. 57.8% and 86.6% vs. 67.7%: p <0.001, respectively) after ICSI. Reduction of the PVP concentration from 10% to 4% and 0% decreased the survival rate of oocytes (95.0% vs. 89.3% vs. 74.6%: p<0.05-0.001) but increased the pronuclear formation rate (74.5% vs. 84.9% vs. 88.6%: p<0.05-0.001). This study demonstrated that technical improvement by clarifying oocyte cytoplasm, cutting the sperm tail and reducing the PVP concentration can significantly benefit ICSI in cattle.
Although transfers of bovine embryos are mostly technically successful, the production of embryos for transfer remains a major problem. Manipulated embryos have been developed in the ligated oviducts of rabbits or sheep until the morulae or blastocyst stage, but these in vivo culture systems remain highly labor and cost intensive. The present paper describes the possible use of mouse oviducts without ligation in an in vivo culture system of in vitro fertilized (IVF) bovine embryos. IVF-derived 2-cell bovine embryos were transferred to the oviducts of pseudopregnant mice and were recovered by flushing the oviducts and the uteri at 5-7 days after the transfer. In the series of 22 experiments, a large proportion of the transferred 2-cell bovine embryos (180 of 307 embryos or 57.1%) were flushed from the oviducts, whereas a small number of embryos (6 embryos or 2.0%) that nearly degenerated were recovered from the uteri. In the recovered embryos, the mean percentage of the embryos that developed to morula or blastocysts was 71.1 ± 24.3%, whereas the ratio in in vitro culture was 33.8 ± 9.2%. The present results suggest that in vivo culture utilizing murine oviducts for the early stage bovine embryos may be available for efficiently obtaining late-stage embryos from farm animals.
The aim of this study was to evaluate the therapeutic effects and safety of progesterone releasing intravaginal device (PRID) in the treatment of inactive ovaries in dairy cattle. The possible influence of PRID on metabolic and/or health status was also examined. A total of 30 anestrous Holstein-Friesian cows, which on rectal palpation had small, flat and smooth or rounded ovaries were used for the experiment. PRID or placebos were inserted into the vagina and left in place for 12 days. Four animals lost the intravaginal device and one was culled. At the time of PRID insertion, the other 25 animals were divided in two groups: 18 with a progesterone concentration ≤1.0 ng/ml (group A), of which 16 were treated with PRID and 2 with placebos, and 7 with a progesterone concentration >1.0 ng/ml (group B), of which 5 were treated with PRID and 2 with placebos. Of the 16 treated animals in group A, 8 (50%) had a corpus luteum (CL) within 14 days after PRID removal. Of the 5 treated animals in group B, 3(60%) had a CL within 14 days after PRID removal. The mean interval from PRID removal to estrus was 2.7 ± 0.3 and 3.0 ± 1.0 days (± SE) in group A and B, respectively. The conception rate of cows in group A that recovered after treatment with PRID, was 28.6%. No significant changes were observed in hematocrit (Ht), WBC and serum levels of glucose, BUN, AST and ALT at the time of PRID insertion and removal, both within and between animals that recovered and those that did not. PRID is an effective treatment for inactive ovaries in dairy cattle and does not adversely affect metabolic and/or health status of animals. Further study is required to improve conception rate at the induced estrus.