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PubMed1989

Amniotic fluid concentration of 5-hydroxyeicosatetraenoic acid is increased in human parturition at term.

5-hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if spontaneous human labor at term is associated with changes in the concentration of this metabolite in amniotic fluid. Fluid was retrieved from 36 women not in labor and from 30 women in active labor at term. 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE of women in labor was significantly greater than that of women not in labor (3538 pg/ml vs. 1977 pg/ml, respectively; p = 0.05). This observation is consistent with activation of the lipoxygenase pathway of arachidonic acid metabolism during spontaneous human parturition at term.

Amniotic Fluid↗

PubMed1994

Immunohistologic detection of non-pancreatic phospholipase A2 (type II) in human placenta and its possible involvement in normal parturition at term.

Placenta is one of the richest sources of non-pancreatic phospholipase A2 (npPLA2) (type II) in the human body, and the enzyme is the key enzyme releasing unsaturated fatty acids from membrane phospholipids. Prostaglandins (PGs) play a critical role in the initiation and progression of parturition. Cytokines are presumed to play a central role in the initiation of normal labor at term, and cytokines are also found to regulate both synthesis and secretion of npPLA2 enzyme. In an attempt to resolve the physiologic function of the npPLA2 enzyme in placental tissue, immunohistologic localization and enzymatic activity measurements of npPLA2 enzyme were performed. NpPLA2 protein was detected in vascular smooth muscle, endothelial cells and connective tissue cells in placenta and umbilical cord, and the protein was weakly stained in trophoblast cells in placenta. Enzymatic activity was not increased in sera from mother nor child compared to sera from healthy individuals, but the activity in amniotic fluid was considerably higher. Our findings support the candidacy for npPLA2 in enzymatic arachidonic acid release from foetal membranes.

Amniotic Fluid↗

PubMed2006

The transcriptome of the uterine cervix before and after spontaneous term parturition.

OBJECTIVE: This study was designed to identify genes differentially expressed in the human uterine cervix after spontaneous term labor. STUDY DESIGN: The transcriptome of cervical tissue was characterized using Affymetrix HG-U133 plus 2 microarrays. Samples were collected from patients at term not in labor (n = 7) and after spontaneous labor (n = 9). Microarray statistical analysis included robust multiarray average, reduction of invariant probes, and permutation analysis for differential expression. Real-time quantitative reverse transcriptase-polymerase chain reaction assays of selected genes were performed on a new set of samples from term patients without labor (n = 10) and patients after spontaneous labor (n = 9). RESULTS: (1) The cervical transcriptome of term patients without labor was dramatically different from that of patients who underwent labor; (2) unique genes (n = 1192) were differentially expressed in the cervical tissue from patients after spontaneous labor, compared with that of the term patients without labor (false discovery rate less than 0.05, absolute fold change greater than 2); (3) Gene Ontology analysis indicated that multiple "Biological Process" categories were enriched, including "response to biotic stimulus," "apoptosis," "epidermis development," and "steroid metabolism"; (4) of major interest, genes involved in neutrophil chemotaxis were dramatically up-regulated in specimens from women after spontaneous labor; (5) real-time quantitative reverse transcriptase-polymerase chain reaction confirmed the increased expression of interleukin-8, interleukin-6, and vascular endothelial growth factor in patients after spontaneous labor; and (6) Toll-like receptor-3 and Toll-like receptor-5 showed decreased gene expression in patients after spontaneous labor. This was confirmed by real-time quantitative reverse transcriptase-polymerase chain reaction. CONCLUSION: (1) Cervical dilatation in term labor is associated with a stereotypic gene expression pattern determined by microarray, which is characterized by overexpression of genes involved in neutrophil chemotaxis, apoptosis, extracellular matrix regulation, and steroid metabolism; (2) Toll-like receptor-3 and Toll-like receptor-5 are differentially regulated during spontaneous parturition at term; and (3) this study provides an unbiased and comprehensive description of the changes in the cervical transcriptome before and after spontaneous term labor.

Adolescent↗

PubMed2005

Parturition following transfer of embryos produced in two media under two oxygen concentrations.

In vitro-produced blastocysts were transferred singly to 99 Angus crossbred recipients. Culture treatments were a 2 x 2 factorial of medium (KSOM or SOF) and oxygen concentration (5 or 20%). At parturition, birth weight and frame measurement before colostrum intake were recorded. Fetal membranes were collected; distribution and diameter of cotyledons was recorded. Cotyledon surface area was calculated. Culture with 5% O2 tended to yield smaller birth weights than culture with 20% O2 (39.7+/-1.3 kg versus 43.1+/-1.4 kg; P < 0.1); this effect was pronounced in KSOM, suggesting a medium by oxygen interaction (P < 0.1). When expressed on a body weight basis, calves born following culture with 20% O2 had consistently smaller skeletal measurements than those from culture with 5% O2. Culture with 20% O2 significantly increased individual cotyledon areas both overall and in the fetal horn and cotyledon surface area in the fetal horn. Overall, individual cotyledons were 32% larger when culture involved 20% O2 versus 5% O2; in the fetal horn the increase was 49%. Cotyledon surface area was greater for 20% compared to 5% O2 culture, though a medium by oxygen interaction was also significant (P < 0.05). Cotyledon surface area in the nonfetal horn was greater for KSOM fetal membranes than those from culture in SOF. There was a significant medium by oxygen interaction for total cotyledon number. These data demonstrate culture system-specific effects on calf and fetal membrane traits.

Animals↗

PubMed1993

Oxytocin modulates oxytocin neurons in the paraventricular nuclei of female rats throughout pregnancy and parturition.

OBJECTIVE: The physiologic roles of nonphasic firing oxytocin neurons in the paraventricular nucleus of female rats throughout pregnancy and parturition was studied from the viewpoint of changes in the membrane activities. STUDY DESIGN: Thin colonal hypothalamic slices containing the paraventricular nucleus were prepared. Immunohistochemical studies of oxytocin in the paraventricular nucleus were performed to determine the localization of oxytocin-containing neurons. Extracellular single neural activities were recorded with a glass micropipette from the oxytocin-dense area, and physiologic concentrations of oxytocin were applied. RESULTS: Nonphasic firing activity was recorded from 61 neurons in virgin female, pregnant, delivering and lactating rats. After bath application of < 5.0 x 10(-11) mol/L of oxytocin, firing rates of 12 of 17 paraventricular neurons in virgin rats decreased and only one increased, whereas the remaining four showed no response to oxytocin. In pregnancy at day 15 all four neurons decreased in activity, whereas at day 21 rats 20 of 26 neurons decreased, two increased, and four showed no response. On the contrary, in delivering rats seven of eight neurons exhibited excitatory responses, and only one showed no response. This excitation reversed to inhibition again after the lactating period ended. CONCLUSION: Negative feedback by oxytocin in virgin and pregnant rats might reverse to positive feedback in delivering and lactating animals as a result of changes in hormonal conditions. This reverse might be closely related to the initiation of delivery.

Action Potentials↗

PubMed1982

Initiation of human parturition.

Arachidonic acid (the precursor of prostaglandins of the 2-series and related compounds) is released from phosphatidylinositol in a reaction sequence catalyzed by three enzymes, i.e., phospholipase C, diacylglycerol lipase, and monoacylglycerol lipase. Diacylglycerol, an intermediate in this pathway, was found in human amnion tissue. The fatty acid composition of the diacylglycerol fraction of amnion tissue was very similar to that of the phosphatidylinositol fraction. The diacylglycerol content of human amnion tissue obtained during early labor was greater than that of amnion tissue obtained before the onset of labor. These findings are supportive of the proposition that arachidonic acid is released from the phosphatidylinositol of amnion tissue during human parturition.

Amnion↗

PubMed1988

Elevated tissue levels of collagenase during dilation of uterine cervix in human parturition.

Seven biopsy specimens from the cervix and 17 from the lower uterine segment were obtained in 24 women at term (37 to 42 weeks). Collagenase was extracted and assayed on telopeptide-free [3H]collagen; typical collagen cleavage products were found on sodium dodecyl sulfate-gel electrophoresis. There was no significant difference between collagenase levels in the cervix and in the lower uterine segment in women not in labor and with the cervix closed. Levels of active and latent collagenase in 11 such specimens were 0.14 +/- 0.03 and 0.64 +/- 0.90 U/gm wet weight, respectively (mean +/- SEM; 1 U = 1 micrograms collagen digested per minute at 30 degrees C). Thirteen women at term in active labor with cervical dilation of 4 to 8 cm exhibited a thirteenfold increase in mean collagenase activity in the lower uterine segment. Active and latent collagenase increased to 2.06 +/- 0.92 and 8.64 +/- 2.87 U/gm, respectively. This is the first direct evidence that interstitial collagenase increases markedly during cervical dilation in human parturition.

Cervix Uteri↗

PubMed1994

Systemic and local cytokine profiles in endotoxin-induced preterm parturition in mice.

OBJECTIVE: Our purpose was to determine whether endotoxin-induced preterm parturition is preceded by a change in the maternal serum and amniotic fluid concentrations of tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha. STUDY DESIGN: C3H/HeN pregnant mice at 15 days of gestation (70% gestation) were randomized to receive an intraperitoneal injection of phosphate-buffered saline solution or lipopolysaccharide (50 micrograms/mouse). Blood (n = 93) and amniotic fluid (n = 58) were collected at 1, 4, and 10 hours after lipopolysaccharide injection. Tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha were determined with sensitive and specific enzyme-linked immunoassays. RESULTS: The injection-to-delivery interval was shorter in mice injected intraperitoneally with 50 micrograms lipopolysaccharide than in phosphate-buffered saline solution-treated mice (median 15.5 hours, range: 10 to 105 hours vs median 88.5 hours, range: 53 to 105 hours; p < 0.001). In comparison with phosphate-buffered saline solution-treated mice, a distinct serum cytokine pattern was observed in lipopolysaccharide-treated mice. Concentrations of tumor necrosis factor-alpha were detectable 1 and 4 hours after lipopolysaccharide injection (median 874 pg/ml, range: < 100 to 8000 pg/ml, p < 0.001; and median 263 pg/ml, range: < 100 to 927 pg/ml, p < 0.001, respectively). Concentrations of interleukin-6 were elevated at 1, 4, and 10 hours (median 11.8 ng/ml, range: 6 to 500 ng/ml, p < 0.001; median 27.1 ng/ml, range: 4.5 to 192 ng/ml, p < 0.001; median 1.95 ng/ml, range: < 0.05 to 35 ng/ml, p < 0.015, respectively). Concentrations of interleukin-1 alpha were significantly increased 4 hours after lipopolysaccharide injection (median 102 pg/ml, range: < 15 to 306 pg/ml, p < 0.001). A cytokine pattern distinct from serum was observed in amniotic fluid of lipopolysaccharide-treated mice. In comparison with controls, concentrations of interleukin-6 were significantly elevated 4 and 10 hours after treatment with lipopolysaccharide (median 0.88 ng/ml, range: 0.40 to 2.7 ng/ml, p < 0.025; and median 4 ng/ml, range: 1.9 to 33.6 ng/ml, p < 0.001, respectively). Interleukin-1 alpha was elevated 10 hours after lipopolysaccharide treatment (median 185.3 pg/ml, range: 38 to 511 pg/ml, p < 0.015). Tumor necrosis factor-alpha was not significantly increased in amniotic fluid. CONCLUSION: Preterm delivery after lipopolysaccharide administration is preceded by the appearance of dramatic increases in maternal serum concentrations of tumor necrosis factor-alpha, interleukin-6, and interleukin-1 alpha and in amniotic fluid concentrations of interleukin-6 and interleukin-1 alpha.

Amniotic Fluid↗

PubMed1996

Nitric oxide synthase activity in the gravid rat uterus decreases a day before the onset of parturition.

OBJECTIVE: Our purpose was to determine the timing, tissue location, and isoform of the uterine nitric oxide synthase activity decrease at term in gravid rat uteri. STUDY DESIGN: Nitric oxide synthase specific activity was assayed in rat uteri 11 through 22 days' gestation by the difference in radiolabeled arginine to citrulline conversion with and without the cofactor reduced nicotinamide adenine dinucleotide phosphate. Nitric oxide synthase isoform was assessed by calcium sensitivity and subcellular location. RESULTS: Rat uterine nitric oxide synthase activity decreased between days 15 and 21 of gestation but did not decrease further at term (day 22), before and after the onset of labor. Decidual nitric oxide synthase activity exceeded the myometrial activity at 15 days' gestation, but then the two were equal at 18 through 22 days' gestation. The nitric oxide synthase activity was calcium insensitive except for half the decidual cytosolic activity on day 15. CONCLUSION: The decrease in pregnant rat uterine nitric oxide synthase activity coincides with the preparation of the uterus for parturition rather than the final activation of labor.

Animals↗

PubMed1997

Changes in activity of cytosolic phospholipase A2 in human amnion at parturition.

OBJECTIVE: The purpose of this study was to determine whether increased cytosolic phospholipase A2 activity mediated arachidonic acid mobilization for prostaglandin synthesis in amnion at parturition. STUDY DESIGN: Amnion was collected immediately after delivery from four groups of patients: preterm (<37 weeks) with no labor or labor and term (>37 weeks) with no labor or labor and stored at -70 degrees C. Tissues were homogenized and centrifuged for 1 hour at 100,000 g, and cytosol was assayed for cytosolic phospholipase A2 activity with use of carbon 14-labeled 1-stearoyl-2 arachidonyl phosphatidylcholine plus 10 micromol/L unlabeled substrate and 5 mmol/L calcium in 10 mmol/L N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid, pH 7.4. Incubations were performed in duplicate +/- 10 micromol/L arachidonyl trifluoromethyl ketone, a specific inhibitor of cytosolic phospholipase A2 activity, at 30 degrees C for 45 minutes. RESULTS: Total cytosolic phospholipase A2 activity (in picomoles of arachidonic acid per minute per milligram of protein) calculated as the difference between the activity in the presence and absence of arachidonyl trifluoromethyl ketone was (mean +/- SE) as follows: preterm no labor (n = 7) 8.94 +/- 3.08, preterm with labor (n = 6) 6.79 +/- 2.31, term no labor (n = 7) 14.85 +/- 1.66, and term with labor (n = 5) 5.51 +/- 1.52. Enzyme activity increased with gestational age and was highest in the term no labor group. A significant decrease in cytosolic phospholipase A2 activity occurred with labor (p < 0.05). The greatest decrease in activity was in the term group (p < 0.05). CONCLUSION: Total cellular cytosolic phospholipase A2 activity in amnion is highest in anticipation of labor but during labor total activity is depleted, resulting in the low activity measured after delivery of the placenta. The substrate specificity and changes in amnion total cytosolic phospholipase A2 activity with labor strongly suggests a role in mediation of arachidonic acid mobilization and prostaglandin synthesis at labor.

Amnion↗

PubMed1998

A fetal systemic inflammatory response is followed by the spontaneous onset of preterm parturition.

OBJECTIVE: There is no evidence for the participation of the human fetus in the mechanisms responsible for the onset of preterm labor. We propose that preterm labor in the setting of infection results from the actions of proinflammatory cytokines secreted as part of the fetal and/or maternal host response to microbial invasion. The objective of this study was to determine whether a systemic fetal inflammatory response, defined as an elevation of fetal plasma interleukin-6 concentrations, has a temporal relationship with the commencement of labor. STUDY DESIGN: After informed consent was obtained, amniocentesis and cordocentesis were performed in 41 patients with preterm premature rupture of membranes who were not in labor on admission. Amniotic fluid was cultured for both aerobic and anaerobic bacteria, as well as for mycoplasmas. Fetal plasma interleukin-6 was assayed by a sensitive and specific immunoassay. Statistical analyses included contingency tables and survival analysis with time-dependent Cox regression hazard modeling. RESULTS: Microbial invasion of the amniotic cavity was present in 58.5% (24/41) of patients. Fetuses with fetal plasma interleukin-6 concentrations > 11 pg/mL had a higher rate of spontaneous preterm delivery within 48 and 72 hours of the procedure than those with fetal plasma interleukin-6 levels < or = 11 pg/mL (88% vs 29% and 88% vs 35%, respectively; P < .05 for all comparisons). Moreover, patients with initiation of labor and delivery within 48 hours of the procedure had a higher proportion of fetuses with plasma interleukin-6 values > 11 pg/mL than patients delivered > 48 hours (58% [7/12] vs 8% [1/13], respectively; P < .05). Survival analysis indicated that fetuses with elevated fetal plasma interleukin-6 levels had a shorter cordocentesis-to-delivery interval than those without elevated fetal plasma interleukin-6 concentrations (median 0.8 days [range 0.1 to 5] vs median 6 days [range 0.2 to 33.6], respectively; P < .05). Time-dependent Cox regression hazard modeling indicated that fetal plasma interleukin-6 level was the only covariate significantly associated with the duration of pregnancy after we adjusted for gestational age, amniotic fluid interleukin-6 level, and the microbiologic state of the amniotic cavity (P < .01). CONCLUSION: A systemic fetal proinflammatory cytokine response is followed by the onset of spontaneous preterm parturition in patients with preterm premature rupture of membranes.

Acute-Phase Reaction↗

PubMed1999

Urinary trypsin inhibitor levels in amniotic fluid of normal human pregnancy: decreased levels observed at parturition.

OBJECTIVE: Urinary trypsin inhibitor, a light chain of inter-alpha-trypsin inhibitor, is reported to inhibit uterine contractility during pregnancy. The objective was to measure amniotic fluid urinary trypsin inhibitor levels in women throughout pregnancy. STUDY DESIGN: We determined levels of urinary trypsin inhibitor in human amniotic fluid (n = 40) by means of Western blot analysis. For quantification, computerized scanning and densitometry were used. Results were analyzed for statistical significance with the Mann-Whitney U test. RESULTS: During pregnancy, mean amniotic fluid urinary trypsin inhibitor levels (+/-SD) were 1.5 +/- 0.22, 1. 2 +/- 0.18, and 0.58 +/- 0.24 micromol/L at 15 to 22 (n = 10), 30 to 35 (n = 5), and 37 to 40 (n = 10) weeks' gestation, respectively. There was a significant negative correlation of urinary trypsin inhibitor level with gestational age. A significant difference was observed in amniotic fluid urinary trypsin inhibitor levels before and after (0.10 +/- 0.03 micromol/L; n = 15) the onset of labor. CONCLUSION: Amniotic fluid urinary trypsin inhibitor levels decrease significantly at term. These results support the hypothesis that parturition may occur through the down-regulation of urinary trypsin inhibitor, which may decrease uterine contractility and maintain the uterus in a state of quiescence during pregnancy.

Amniotic Fluid↗

PubMed1998

Reversible translocation of CTP:phosphocholine cytidylyltransferase from cytosol to membranes in the adult bovine liver around parturition.

The key regulatory enzyme of phosphatidylcholine (PC) synthesis, CTP:phosphocholine cytidylyltransferase (CT), is known to be activated in vitro by translocation from soluble to particulate fractions of the cell. In the present study the periparturient cow was chosen as a model to investigate whether translocation of CT can contribute to the regulation of PC synthesis in vivo. Between parturition and 1.5 weeks post-partum, the cytosolic CT activity in the liver of the adult animal decreased 1.9-fold, and this correlated with a 1.8-fold increase in microsomal CT activity. At that time, microsomal CT activity started to decline again whereas the cytosolic activity rose concomitantly until both activities reached their pre-partum values at 8 weeks post-partum. The activities of soluble and membrane-bound CTP:phosphoethanolamine cytidylyltransferase (ET), the analogous enzyme in the CDP-ethanolamine pathway, did not change significantly throughout this period. Whereas hepatic PC concentrations declined until about 2 weeks post-partum and thereafter gradually returned to pre-partum levels, the PC levels in very-low-density-lipoproteins, started to rise 2 weeks after the partus reaching a maximum of 219% of the original value at 8 weeks post-partum. These results strongly suggest that there is a reversible redistribution of CT between cytosol and membranes in a physiologically relevant animal model, supporting the concept that translocation of CT is occurring in vivo.

Animals↗

PubMed2000

Parturition hormone in the tsetse Glossina morsitans: activity in reproductive tissues from other species and response of tsetse to identified neuropeptides and other neuroactive compounds.

Parturition hormone (PH) activity is present not only in the uterus of the tsetse Glossina morsitans but also in the oviducts of Bombyx mori and Schistocerca gregaria, as well as the ejaculatory duct of S. gregaria males. Activity thus appears to be present in the reproductive ducts of diverse insect taxa. To determine whether any of the common insect neuropeptides are capable of mimicking the effect of PH, 35 identified neuropeptides and analogs were evaluated for PH activity. Modest PH activity was observed for only high doses of proctolin and a pyrokinin analog, thus suggesting that PH is unlikely to be closely related to any of the identified neuropeptides tested. While proctolin was highly effective in stimulating contractions of the S. gregaria oviduct, the extract from the tsetse uterus elicited only a weak response in this bioassay. PH activity was, however, effectively mimicked with an injection of 8 bromo-cyclic GMP, thus suggesting a potential role for this cyclic nucleotide in mediating the PH response. Pregnant females were responsive to PH, other neuropeptides and cyclic nucleotides only when females were neck-ligated. In intact females, the brain can presumably override the stimulation provided by the active compounds.

Journal Article↗

PubMed1976

Massive renal hemorrhage associated with parturition.

Spontaneous massive renal hemorrhage, during or after parturition, not associated with blood dyscrasias or other recognizable etiology is rare. Two new cases are added to the 7 cases previously reported. The related literature is reviewed.

Adult↗

PubMed1997

Parturition: steroids, prostaglandin E2, and expression of adhesion molecules by endothelial cells.

OBJECTIVE: To determine whether 17 beta-estradiol, progesterone, and prostaglandin (PG) E2, alone or in combination with cytokines, influence the adhesiveness of vascular endothelium and thus play a role in the first stage of leukocyte infiltration of the uterine cervix during parturition. METHODS: Cultured umbilical vein endothelial cells obtained from 11 women after vaginal delivery at term were incubated with 17 beta-estradiol, progesterone, PGE2, tumor necrosis factor alpha (TNF-alpha), and interleukin-8, (IL-8), alone and in combination. The expression of endothelial leukocyte adhesion molecule-1, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was investigated by immunofluorescence and flow cytometry. The Kolmogorov-Smirnov test was used for statistical analysis. RESULTS: We found that 17 beta-estradiol augmented the TNF-alpha-induced expression of endothelial leukocyte adhesion molecule-1, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 by 107, 9, and 39%, respectively. Alone, 17 beta-estradiol induced the expression of only intercellular adhesion molecule-1 (24%), as did PGE2 (13%). Neither progesterone nor IL-8 induced expression of any of these adhesion molecules. CONCLUSIONS: Unlike progesterone, 17 beta-estradiol and PGE2 stimulate the expression of adhesion molecules in vitro and may, therefore, promote adhesion of granulocytes to capillary endothelium.

Cells, Cultured↗

PubMed2001

Physiological roles for the neurosteroid allopregnanolone in the modulation of brain function during pregnancy and parturition.

Allopregnanolone is a well-established allosteric modulator of the GABAA receptor but its physiological roles within the nervous system remain unclear. Derived principally from circulating progesterone, allopregnanolone achieves its highest concentrations within the nervous system during late pregnancy and recent studies have now begun to elucidate its roles at this time in the rat. At the molecular level it is clear that the regulation of GABAA receptor subunit gene expression by progesterone and its derivatives occurs in a subunit- and a neuron-specific manner and that both progesterone and allopregnanolone are involved. At the cellular level, the increasing concentrations of allopregnanolone with advancing pregnancy can be shown to have important physiological actions in repressing the electrical activity of specific neuronal phenotypes such as the magnocellular oxytocin neurons. The marked fall in progesterone and allopregnanolone concentrations prior to parturition equally appears to have a substantial impact upon GABAA receptor signaling in the hippocampus, frontal cortex and oxytocin neurons. Together, studies at a basic level suggest that the rise and fall in allopregnanolone concentrations during pregnancy are likely to exert a powerful regulatory influence upon neurotransmission in a variety of brain networks. The temporal correlation between these events and the observed cognitive, psychiatric and physiological changes associated with pregnancy and the peri-partum period in humans is striking and warrants close attention.

Animals↗

PubMed1996

Techniques developed for the control of estrus, ovulation and parturition in the East German pig industry: a review.

Centralized administration of the nationalized pig industry in the former German Democratic Republic (East Germany), promoted wide-scale use of assisted reproduction of pigs. The objective was to synchronize reproductive events such as estrus, ovulation, breeding and parturition in a way that would allow for quick penetration of desirable genetic information by timed artificial insemination and the routine use of hygienic measures. Methods developed to control these events were based on extensive basic and applied research, but the resulting pool of unique scientific information was heretofore not published in refereed journals in the English language. We present here a comprehensive review of biotechnological procedures and physiological insights gained by basic and applied research and by their application at the large pig production units.

Journal Article↗