"Capacitation is a complex molecular process that results in changes of calcium concentration, protein phosphorylation, acrosomal matrix and membrane rearrangement. As a complex biological process, capacitation can be influenced by many molecular factors in the uterine and oviductal fluid  and the effect of uterine and oviductal fluids depends on the specific stages of the estrous cycle . Although capacitation naturally occurs in the female reproductive tract, it can be also performed in vitro using specific media and physical conditions [6,7]. "
[Show abstract][Hide abstract] ABSTRACT: Mammalian sperm must undergo a series of controlled molecular processes in the female reproductive tract called capacitation before they are capable of penetrating and fertilizing the egg. Capacitation, as a complex biological process, is influenced by many molecular factors, among which steroidal hormone estrogens play their role. Estrogens, present in a high concentration in the female reproductive tract are generally considered as primarily female hormones. However, there is increasing evidence of their important impact on male reproductive parameters. The purpose of this study is to investigate the effect of three natural estrogens such as estrone (E1), 17beta-estradiol (E2) and estriol (E3) as well as the synthetical one, 17 alpha-ethynylestradiol (EE2) on boar sperm capacitation in vitro.
Boar sperm were capacitated in vitro in presence of estrogens. Capacitation progress in control and experimental samples was analyzed by flow cytometry with the anti-acrosin monoclonal antibody (ACR.2) at selected times of incubation. Sperm samples were analyzed at 120 min of capacitation by CTC (chlortetracycline) assay, immunocytochemistry and flow cytometry with anti-acrosin ACR.2 antibody. Furthermore, sperm samples and capacitating media were analyzed by immunocytochemistry, ELISA with the ACR.2 antibody, and the acrosin activity assay after induced acrosomal reaction (AR).
Estrogens stimulate sperm capacitation of boar sperm collected from different individuals. The stimulatory effect depends on capacitation time and is highly influenced by differences in the response to estrogens such as E2 by individual animals. Individual estrogens have relatively same effect on capacitation progress. In the boar samples with high estrogen responsiveness, estrogens stimulate the capacitation progress in a concentration-dependent manner. Furthermore, estrogens significantly increase the number of acrosome-reacted sperm after zona pellucida- induced acrosomal reaction.
We demonstrate here the stimulatory effect of four different estrogens on boar sperm capacitation in vitro. According to our results, there is significant difference in the response to tested estrogens at different capacitation time and among individual animals. In animals with a high response to estrogens, there is a concentration-dependent stimulation of capacitation and individual estrogens have relatively the same effect. Effects of individual estrogens, differences in the response to them by individual animals, their time and concentration-dependent outcomes further contribute to our knowledge about steroidal action in sperm.
"In response to various hormonal conditions the oviduct undergoes changes in the secretory processes of the epithelium, the volume and composition of the fluid, and the activity of the musculature (see review by Hamner, 1973). These environmental changes can influence gamete transport (Boling & Blandau, 1971; Spilman, Shaikh & Harper, 1978), sperm capacitation (Chang, 1958; Bedford, 1970; Brown & Hamner, 1971), and early embryonic development (Chang, 1950; Adams, 1973; Kille & Hamner, 1973). Steroid hormones are also reported to have direct effects on spermatozoa (Mounib, 1964; Ericsson, Cornette & Buthala, 1967; Gwatkin & Williams, 1970; Briggs, 1973; Bleau, Vandenheuwel, Andersen & Gwatkin, 1975) and embryos (Daniel, 1964; Daniel & Levy, 1964; Ketchel & Pincus, 1964; McGaughey & Daniel, 1966). "
[Show abstract][Hide abstract] ABSTRACT: The concentrations of progesterone and oestradiol in the oviducal fluid during oestrus and pseudopregnancy were measured. Progesterone concentrations ranged from 0.55 +/- 0.17 ng/ml during oestrus to a maximum of 2.86 +/- 0.82 ng/ml on Day 12 of pseudopregnancy. Serum progesterone concentrations were similar to those found in oviduct fluid during oestrus, but by Day 12 serum levels had risen to 14.13 +/- 1.97 ng/ml. Daily oviducal fluid oestradiol values ranged from 48.3 +/- 6.4 pg/ml to 119.7 +/- 23.6 pg/ml and were similar to serum concentrations.
[Show abstract][Hide abstract] ABSTRACT: The postovulatory fertile life of mammalian eggs is remarkably short (approximately 6-36h). Anomalies of embryogenesis may result from fertilization of aged, defective eggs. Attempts to study this problem using whole-animal models are complicated by chances in the natural milieu of the gametes. In the present study, postovulatory hamster eggs were allowed to agein vivo then fertilized in vitro. Cumulus-intact eggs recovered from superovulated hamsters either 2 or 9 h after the estiated time of ovulation (12 h postHCG) were incubated for 4 h with preincubated sperm suspentions in a modified Tyrode's solution devised for in vitro fertilization. Eggs were either fixed or cultured for another 20h in fresh medium to allow cleavage to occur, then examined by light microscopy (phase and interference-contrast). No significant difference was found in the ablities of fresh and aged eggs to be penetrated by spermatozoa (94% vs 90%, respectively; 8 replicated experiments), but only 59% of penetrated aged eggs were found to undergo morphologically normally fertilization (2 polar bodies, 2 prounclei) compared with 75% of fresh eggs (difference significant, P< 0.01). About 13% of eggs were polyspermic in both categories. The most common anomaly in aged fertilied egges was failure to extrude the second polor body (23% off eggs vs 8% of fresh eggs, P < 0.01). Only 21% of aged eggs underwent first cleavaage, and only 74% of these appeared morphologically normal, compared with value of 68% and 98%, respectively, for fresh eggs. These data show that in the hamster, abnormal fertilization and cleavage failure can, in part, be directly attributed to postovulatory deterioration of eggs. We also infer that the apparently very short penetrable life of hamster eggs in vivo shown by previous investigators is an indirect effect of postovulatory changes in the female reproductive tract that are unfavorable for sperm-egg interactions.
Gamete Research 01/1983; 8(3):219-230. DOI:10.1002/mrd.1120080303
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