Progesterone receptors in the endometrium of normal and repeat-breeder cows

Progesterone receptors were measured in the cytosol and nuclear fractions of endometrial cells from repeat-breeder (RB) and normal (NB) cows on day 6 post-breeding (inseminated group) and on days 3, 6 and 7 after estrus (non-inseminated group). Results were related to both the type of cow and the condition of the embryo present within the uterus in the inseminated groups. Cows carrying morphologically abnormal embryos showed higher concentrations of cytosolic progesterone receptors as compared with the normal group, regardless of the type of cow. Within the normal embryo group, RB cows had higher concentrations of progesterone receptors than NB. The same tendency toward higher concentrations of progesterone receptors in RB cows was observed in the non-inseminated groups. The results of this study suggest the existence of a local hormonal imbalance, which may be related to the repeat-breeding problem.     

Endometrial expression of selected transcripts involved in prostaglandin synthesis in cows with endometritis

Several cytokines and prostaglandins play an important role in preparing the endometrium for implantation and mediating pro-inflammatory events. The aim of the present study was to examine mRNA expression of interleukin 1α (IL-1α), interleukin receptor antagonist (IL-1-RN), cytosolic prostaglandin E synthase (cPGES), microsomal PGES (mPGES-1 and mPGES-2) and lipocalin-type PGDS (L-PGDS) in the bovine endometrium. Endometrial epithelium samples were collected ex vivo from cows with different status of health at day 21-27 postpartum on a dairy farm. Three groups (n = 9 animals each) were defined: (1) healthy cows with no signs of endometritis (control group), (2) cows with subclinical endometritis, and (3) cows with signs of clinical endometritis. Oestrous cycle-dependent mRNA expression pattern was investigated using bovine endometrial epithelial cells from healthy uteri collected at the abattoir. These uteri were classified into post-ovulatory, early-to-mid luteal, late luteal or pre-ovulatory phase (n = 8 animals for each cycle phase). After collecting endometrial epithelium using the cytobrush-method, mRNA analysis was performed by real-time RT-PCR. L-PGDS, IL-1α and IL-1-RN mRNA were expressed significantly higher (P < 0.05) in the endometrium of cows with subclinical or clinical endometritis compared with healthy cows. A twofold lower cPGES mRNA expression (P < 0.05) was detected in cows with subclinical endometritis compared to healthy cows. L-PGDS and IL-1-RN mRNA expression was increased (P < 0.05) after ovulation compared with the pre-ovulatory or luteal phase, respectively. These results support the hypothesis that a dys-regulated cytokine and/or prostaglandin profile in the uterus could be induced by subclinical endometritis or clinical endometritis.     

Lipopolysaccharide (LPS) suppresses follicle development marker expression and enhances cytokine expressions,which results in fail to granulosa cell proliferation in developing follicle in cows

Postpartum endometritis is known to be associated with ovarian dysfunction in cows. Lipopolysaccharide (LPS) generated by Gram-negative bacteria is recognized by toll-like receptor 4 (TLR4), which leads to an inflammatory response by the generation of cytokines such as tumor necrosis factor-α (TNF-α) and interleukins. In this study, we investigated the effect of endometrial LPS on granulosa cell functions during early follicular development in cows. Uteri and follicles were obtained from a slaughterhouse and classified into either clinical endometritis (CE) or normal groups by vaginal mucus test. TLR4 mRNA and protein in normal cows were expressed in granulosa cells collected from follicles measuring 1–3 and 4–7 mm in a diameter, respectively. LPS content in endometrium and follicular fluid of CE cows was significantly higher than that in normal cows. Compared to normal cows, CE cows showed lower expression of follicular development markers (FSHR, CYP19A1, CCND2, and LHCGR) in granulosa cells, lower estradiol-17β concentrations in follicular fluid, and lower granulosa cell proliferation. CE contraction significantly increased cytokine expressions (TNF, IL-1A, and IL-1B) in granulosa cells and suppressed apoptosis of granulosa cells compared to normal cows. LPS significantly suppressed the expression of follicular development markers and the production of estradiol-17β in granulosa cells and reduced granulosa cells proliferation compared to cells cultured without LPS. LPS significantly increased cytokine expressions and suppressed granulosa cell apoptosis. Thus, the present results suggest that the existence of LPS in developing follicles is one of the causes of ovarian quiescence in cows.     

Different expression of PGE synthase,PGF receptor,TNF, Fas and oxytocin in the bovine corpus luteum of the estrous cycle and pregnancy

Functional differences between the corpus luteum (CL) of pregnancy and CL of the cycle in cows were examined. Messenger RNA and protein levels of prostaglandin (PG) E synthase (PGES), PGF2α receptor (PGFR), tumor necrosis factor-α (TNF) and Fas were found to be higher in the CL of pregnancy than in CL of the cycle. Oxytocin (OT) mRNA and protein levels were lower in the CL of pregnancy. Messenger RNA levels of progesterone receptor (PR), luteinizing hormone receptor (LHR), PGE2 receptor (PGER), PGF synthase (PGFS), TNF receptor type I (TNFRI) and TNF receptor type II (TNFRII) did not differ between the cycle and pregnancy. PGE2 and PGF2α production by cultured bovine endometrial tissues was decreased by a supernatant derived from the homogenized CL of pregnancy but not by that of the CL of the cycle, suggesting that specific substances in the CL of pregnancy affect endometrial PG production in cows. Collectively, PGES, PGFR, TNF, Fas or OT may contribute to differences between the CL of pregnancy and CL of the estrous cycle in cows.     

Immunohistochemical assessment of prostaglandin H-synthase in bovine endometrial biopsy samples collected throughout the oestrous cycle

The study was designed to determine the distribution of prostaglandin H-synthase (PGS) also known as cyclooxygenase in specific uterine cell populations during the oestrous cycle. Endometrial biopsy samples were obtained from a total of 10 clinically healthy cows at days 1 (initiation of behavioural oestrus), 8, 15, and 19 of the oestrous cycle. All animals conceived after biopsy regimen. Data of semiquantitatively scored immunoreactivities were analysed using analyses of variance, t-tests for paired data and correlation analyses. Biotin-streptavidin-peroxidase immunostaining technique was employed to localise PGS. Specific staining was consistently present in endothelial cells of arteries but not capillaries and venules. A gradient of staining intensity was clearly apparent within the endometrium: surface epithelial cells and stromal cells located near the endometrial surface are consistently stained more intensely than glandular epithelial cells and stromal cells lying deeper in the endometrium. Days of oestrous cycle also influenced PGS immunoreactivities. Generally, higher immunoreactivities were recorded in surface epithelium, uterine glands and endometrial stromal cells at cycle days 1 and 19 as compared to cycle days 8 and 15. Minimal scoring values were mainly found at cycle day 8. The results of the present study suggest that the amount of bovine endometrial PGS varies considerably with the day of cycle in the above mentioned cell-type- and location-restricted manner. Therefore, the capacity of the bovine uterine mucosa for prostaglandin production may—amongst other factors—depend on the cycle-restricted availability of the respective enzyme systems.     

Ultrastructure of human blastocyst-endometrial interactions in vitro

The interactions of seven human blastocysts with cultured endometrial cells were investigated by light microscopy and transmission electron microscopy. Trophoblastic-endometrial contact was observed at the lateral border of endometrial epithelial cells where trophoblast and endometrial epithelial cells shared apical junctional complexes and desmosomes. The first sign of penetration was invasion of a trophoblastic cytoplasmic protrusion between endometrial epithelial cells. In broad contact areas, lateral displacement of endometrial epithelial cells and formation of a peripheral pseudostratified epithelium were observed. When trophoblastic cells were interposed fully among endometrial epithelial cells, they formed a penetration cone and appeared to dislodge endometrial epithelial cells from the stromal compartment. A single penetration cone only was found in each specimen. Endometrial or trophoblastic degeneration was not observed. Formation of multinucleate (>/= three nuclei per cell) trophoblast cells was not observed, but many cells displayed areas with abrupt disappearance of well-defined plasma membranes, which is indicative of syncytium formation. In this study, adhesion and penetration occurred at the same time. The human blastocysts penetrated the endometrial surface epithelium by intrusive penetration. Epithelial penetration was achieved primarily by cellular syncytiotrophoblast-like cells and the first indications of syncytium formation were observed simultaneously with penetration of the epithelium.     

Postpartum endometrial cytology in beef cows

The objectives were to characterize postpartum endometrial cytology and to determine the prevalence of subclinical endometrial inflammation and its impact on reproduction in beef cows. Samples for endometrial cytology (low-volume uterine lavage) were obtained from 135 of 137 Angus cows (2-87 d postpartum) in northern Minnesota, 26 d before breeding started. Agreement between examiners for subjective inflammation scores was very high (kappa = 0.971); the correlation between these scores and PMN counts was high (r = 0.83; P < 0.001), validating subjective categorization. The proportion of PMN and large mononuclear cells (principally macrophages) declined with postpartum interval (P < 0.001), whereas small mononuclear cells were consistently present (and not significantly affected by postpartum interval). Pregnancy rate to fixed-time AI was 29% and overall pregnancy rate was 89%. There was no association between cell type and ultimate pregnancy status or day of conception (P > 0.10). Although inflammation later in the postpartum period apparently impaired subsequent reproduction in dairy cows, in cows >50 d postpartum at sample collection in the present study, no cytological parameter significantly predicted final pregnancy status or day of conception. Previous twinning increased the risk of subclinical endometritis (P = 0.02), but not the probability of becoming pregnant (P = 0.14). In conclusion, we inferred that beef cows had the ability to clear uterine inflammation after resumption of ovarian cyclicity.     

An RXR-Selective Analog Attenuates the RARα-Selective Analog-Induced Differentiation and Non-G1-Restricted Growth Arrest of NB4 Cells

NB4, a human acute promyelocytic leukemia cell line expressing the promyelocyte–retinoic acid receptor α (PML–RARα) hybrid protein was treated with RAR- and retinoid X receptor (RXR)-selective analogs to determine their effects on cell proliferation, retinoblastoma (RB) tumor-suppressor protein phosphorylation, and differentiation. An RAR- or just RARα-selective analog alone induced similar cell population growth arrest, cell cycle arrest without restriction to G₁, hypophosphorylation of RB, and myelomonocytic cell surface differentiation marker expression (CD11b). In addition, an RARα antagonist could inhibit the effects of the RARα agonist completely. The RARα-selective analog-elicited response was attenuated by simultaneous addition of various RXR-selective analogs. In contrast, each of the RXR-selective analogs was unable to induce any of the cellular responses analyzed. The growth arrest of NB4 cells is not G₁-restricted and occurs at all points in the cell cycle. Cells growth arrested by treatment with an RARα-selective analog show primarily hypophosphorylated RB. When these cells are sorted into G₁or S + G₂/M subpopulations by flow cytometry, hypophosphorylated RB protein was in G₁as well as S + G₂/M cells. This suggests that the hypophosphorylated RB protein may be mediating the growth arrest of NB4 cells at all points in the cell cycle. These results are consistent with an involvement of PML–RARα and/or RARα in the transduction of the retinoid signal in NB4 cells.     

Differential abundance of IGF1, bile acids,and the genes involved in their signaling in the dominant follicle microenvironment of lactating cows and nulliparous heifers

It is well documented that incidence of fertility problems is high in lactating cows but not in heifers of the same genetic merit. Understanding the metabolic and molecular differences between fertile heifers and relatively infertile lactating cows will help us understand the pathogenesis of infertility in dairy cows. Follicular waves in lactating cows (30–50 days in milk; n = 12) and heifers (n = 10) were synchronized by ultrasound-guided follicle ablation. Follicular fluid and granulosa cells of the dominant follicle were collected by ultrasound-guided aspiration along with blood sampling on Day 6 after synchronization. Dominant and subordinate follicles were larger in lactating cows than in heifers. Metabolic stress in lactating cows was evidenced by lower glucose and higher ß-hydroxy butyric acid compared with heifers. Insulin-like growth factor 1 signaling was reduced in the dominant follicle in lactating cows through reduced insulin-like growth factor 1 concentrations in plasma and follicular fluid of the dominant follicle, and reduced expression of pregnancy-associated plasma protein A (PAPPA) in their granulosa cells. We also found increased levels of total bile acids in the follicular fluid of the dominant follicle of lactating cows compared with heifers. Granulosa cells of the dominant follicle had higher expression of SLC10A2 and GPBAR1 (bile acid transporter and receptor, respectively) in lactating cows. These novel data are indicative of increased bile acid signaling within the dominant follicles of lactating cows compared with heifers. Overall, we demonstrate in the present study the metabolic, endocrine, and molecular differences within the microenvironment of the dominant follicles in lactating cows and heifers. These differences in follicular microenvironment may contribute toward abnormal ovarian function in lactating dairy cows.     

N-acetyl-beta-D-glucosaminidase activity in bovine uterine fluid and blood serum during the postpartum period

Uterine fluid and serum N-acetyl-beta-D-glucosaminidase (NAGase) was determined in cows during the first 32 d post partum following normal and abnormal parturitions. Both uterine fluid and serum NAGase activities were elevated after calving and then started to decline gradually toward the 32nd day after calving, when they reached their lowest concentrations. No significant differences were found between the mean NAGase concentrations in uterine fluid of the two groups, although significant differences were found between the mean values of the combined groups between days. With serum NAGase concentrations, significant differences (P<0.01) were found between the mean values of the normal and abnormal puerperium groups. The major part of the enzyme detected in postpartum uterine fluid is probably contributed by epithelial cells present in the fluid. Uterine leucocytes and endometrial cell damage caused by bacterial infection may also contribute to the total NAGase activity in uterine fluid.     

Comparative analysis of some aspects of mitochondrial metabolism in differentiated and undifferentiated neuroblastoma cells

The aim of the present study is to clarify some aspects of the mechanisms of regulation of mitochondrial metabolism in neuroblastoma (NB) cells. Experiments were performed on murine Neuro-2a (N2a) cell line, and the same cells differentiated by all-trans-retinoic acid (dN2a) served as in vitro model of normal neurons. Oxygraphy and Metabolic Control Analysis (MCA) were applied to characterize the function of mitochondrial oxidative phosphorylation (OXPHOS) in NB cells. Flux control coefficients (FCCs) for components of the OXPHOS system were determined using titration studies with specific non-competitive inhibitors in the presence of exogenously added ADP. Respiration rates of undifferentiated Neuro-2a cells (uN2a) and the FCC of Complex-II in these cells were found to be considerably lower than those in dN2a cells. Our results show that NB is not an exclusively glycolytic tumor and could produce a considerable part of ATP via OXPHOS. Two important enzymes - hexokinase-2 and adenylate kinase-2 can play a role in the generation of ATP in NB cells. MCA has shown that in uN2a cells the key sites in the regulation of OXPHOS are complexes I, II and IV, whereas in dN2a cells complexes II and IV. Results obtained for the phosphate and adenine nucleotide carriers showed that in dN2a cells these carriers exerted lower control over the OXPHOS than in undifferentiated cells. The sum of FCCs for both types of NB cells was found to exceed significantly that for normal cells suggesting that in these cells the respiratory chain was somehow reorganized or assembled into large supercomplexes.     

Deletion of autophagy inducer RB1CC1 results in degeneration of the retinal pigment epithelium

Autophagy regulates cellular homeostasis and response to environmental stress. Within the retinal pigment epithelium (RPE) of the eye, the level of autophagy can change with both age and disease. The purpose of this study is to determine the relationship between reduced autophagy and age-related degeneration of the RPE. The gene encoding RB1CC1/FIP200 (RB1-inducible coiled-coil 1), a protein essential for induction of autophagy, was selectively knocked out in the RPE by crossing Best1-Cre mice with mice in which the Rb1cc1 gene was flanked with Lox-P sites (Rb1cc1^flox/flox). Ex vivo and in vivo analyses, including western blot, immunohistochemistry, transmission electron microscopy, fundus photography, optical coherence tomography, fluorescein angiography, and electroretinography were performed to assess the structure and function of the retina as a function of age. Deletion of Rb1cc1 resulted in multiple autophagy defects within the RPE including decreased conversion of LC3-I to LC3-II, accumulation of autophagy-targeted precursors, and increased numbers of mitochondria. Age-dependent degeneration of the RPE occurred, with formation of atrophic patches, subretinal migration of activated microglial cells, subRPE deposition of inflammatory and oxidatively damaged proteins, subretinal drusenoid deposits, and occasional foci of choroidal neovascularization. There was secondary loss of photoreceptors overlying the degenerated RPE and reduction in the electroretinogram. These observations are consistent with a critical role of autophagy in the maintenance of normal homeostasis in the aging RPE, and indicate that disruption of autophagy leads to retinal phenotypes associated with age-related degeneration.     

Automated nuclear image morphometry on fine needle aspiration smears of malignant round cell tumors

OBJECTIVE: To analyze nuclear image morphometry in fine needle aspiration cytology smears of different groups of malignant round cell tumors (MRCTs) to evaluate its diagnostic role. STUDY DESIGN: In this study there were 55 cases of MRCT, consisting of 18 Ewing's sarcoma (EW), 10 neuroblastoma (NB), 5 non-Hodgkin's lymphoma (NHL), 6 rhabdomyosarcoma (RMS), 4 peripheral neuroectodermal tumor (PNET), 8 Wilm's tumor (WT), 2 retinoblastoma (RB) and 2 undifferentiated round cell tumor (URCT). A Leica image cytometer with Quantimet 600 software (Leica, Cambridge, U.K) was used to measure nuclear area, nuclear diameter, nuclear perimeter, nuclear convex perimeter (CP), nuclear roundness and nuclear convex area on hematoxylin and eosin-stained cytologic smears. At least 100 cells were studied in each case. RESULTS: The RB group of tumors showed the highest mean nuclear area (NA), convex area (CA), CP, diameter (D), perimeter (P) and roundness (R). RMS had the highest mean CA, and URCT had the highest mean roundness. ANOVA was performed on the tumors and showed significant differences for all the variables in all the groups (P < .000). All the morphometric data (except roundness) were significantly different in RMS versus all other MRCTs except RB. Similarly, morphometric data on WT were also significantly different from that on NHL. Most of the morphometric data (except CA and R) showed significant differences between RB and all other MRCTs except RMS. PNET, EW and NB could not be differentiated with those variables. CONCLUSION: RMS and RB could successfully be differentiated from all other MRCTs with the help of morphometry. It was not possible to differentiate RMS and RB by image cytometry (ICM) since the ICM data overlapped in those two groups. It was possible to differentiate WT and NHL with ICM. Nuclear ICM was not significantly different in the NB, PNET and ES groups, and probably ICM would not be very helpful to differentiate these groups of MRCT.     

Absence of Inhibin Alpha and Retinoblastoma Protein Leads to Early Sertoli Cell Dysfunction

Sertoli cells, the support cells of mammalian spermatogenesis, are regulated by a number of nuclear factors and express retinoblastoma (RB) tumor suppressor protein. We hypothesized that RB is an important mediator of Sertoli cell tumorigenesis in inhibin α knockout (Inha KO) mice. In our previous mouse studies, we found that conditional knockout (cKO) of Rb in Sertoli cells caused progressive Sertoli cell dysfunction. Initially, loss of RB had no gross effect on Sertoli cell function as the mice were fertile with normal testis weights at 6 weeks of age, but by 10–14 weeks of age, mutant mice demonstrated severe Sertoli cell dysfunction and infertility. Although double knockout (dKO) of Rb and Inha did not result in exacerbation of the tumorigenic phenotype of Inha-null mice, we found that the dKO mice demonstrate an acceleration of Sertoli cell dysfunction compared to Rb cKO mice. Specifically, in contrast to Rb cKO mice, Inha/Rb dKO mice showed signs of Sertoli cell dysfunction as early as 4 weeks of age. These results demonstrate that RB is not essential for Sertoli cell tumorigenesis in Inha KO mice but that loss of Inha accelerates the infertility phenotype of Rb cKO mice.     

Expression of the NSE,SP,NFH and DβH in normal and cryptorchid testes of Bactrian camel

Neuroendocrine substances play essential roles in regulating the normal physiological functions of testicles. The purpose of this study is to explore the localization and effects of four neuroendocrine markers (NSE, SP, NFH and DβH) in normal and cryptorchid testes of Bactrian camels using western blotting, transmission electron microscopy, immunohistochemistry, and immunofluorescence methods. The results showed that cryptorchidism caused a reduction in layers of spermatogenic epithelium and decreased glycogen positivity in the basement membrane. The ultrastructure revealed that macrophages were always found around the Leydig cells, crowded with swelling mitochondria in cryptorchidism. Expression of NSE in the Leydig cells of cryptorchidism was significantly weakened compared to that in the normal group(p<0.01). We found that SP was always distributed along the nerve fibers in normal testes and was expressed in the Leydig cells of cryptorchidism. However, expression of NFH in the cryptorchidic tissue was strongly positive in the spermatogenic epithelium, with limited expression in Leydig cells and no expression in peritubular myoid cells. Therefore, the expression of DβH in the Sertoli cells was comparatively strong in both the normal and cryptorchidism groups. NFH and DβH expression was significantly increased in the cryptorchidism group compared with the normal group (p<0.01). These findings indicated that the underdeveloped seminiferous epithelium and pathological changes in cryptorchid tissue in Bactrian camels were potentially related to a disorder in glycoprotein metabolism. Our results suggest that NSE and SP could help judge the pathological changes of cryptorchidism. The present study provides the first evidence at the protein level for the existence of NFH and DβH in Sertoli and Leydig cells in Bactrian camel cryptorchidism and provides a more in-depth understanding of neuroendocrine regulation is crucial for animal cryptorchidism.     

Ultrasound Targeted Apoptosis Imaging in Monitoring Early Tumor Response of Trastuzumab in a Murine Tumor Xenograft Model of Her-2–Positive Breast Cancer1

OBJECTIVE: Our study aimed to monitor the trastuzumab therapy response of murine tumor xenograft model with human epidermal growth factor receptor 2 (Her-2)–positive breast cancer using ultrasound targeted apoptosis imaging. METHODS: We prepared targeted apoptosis ultrasound probes by nanobubble (NB) binding with Annexin V. In vitro, we investigated the binding rate of NB–Annexin V with breast cancer apoptotic cells after the trastuzumab treatment. In vivo, tumor-bearing mice underwent ultrasound targeted imaging over 7 days. After imaging was completed, the tumors were excised to determine Her-2 and caspase-3 expression by immunohistochemistry (IHC). The correlation between parameters of imaging and histologic results was then analyzed. RESULTS: For seeking the ability of targeted NB binding with apoptotic tumor cells (Her-2 positive), we found that binding rate in the treatment group was higher than that of the control group in vitro (P = .001). There were no differences of tumor sizes in all groups over the treatment process in vivo (P = .98). However, when using ultrasound imaging to visualize tumors by targeted NB in vivo, we observed that the mean and peak intensities from NBs gradually increased in the treatment group after trastuzumab therapy (P = .001). Furthermore, these two parameters were significantly associated with caspase-3 expression of tumor excised samples (P = .0001). CONCLUSION: Ultrasound targeted apoptosis imaging can be a non-invasive technique to evaluate the early breast tumor response to trastuzumab therapy.     

Assessment of Early Postpartum Reproductive Performance in Two High Producing Estonian Dairy Herds

Early postpartum (6 weeks) ovarian activity, hormonal profiles, uterine involution, uterine infections, serum electrolytes, glucose, milk acetoacetate and blood urea nitrogen (BUN) levels were studied in 2 Estonian high producing dairy herd with annual milk production of 7688 (Farm A) and 9425 (Farm B). From each farm 10 cows, with normal calving performance were used. Blood samples for the hormonal (PGF_2α-metabolite, progesterone) analyses were withdrawn. On day 25 PP blood serum samples were taken for the evaluation of metabolic/electrolyte status. On the same day estimation of milk acetoacetate values was done. The ultrasound (US) was started on day 7 PP and was performed every 3^rd day until the end of experiment. Uterine content, follicular activity and sizes of the largest follicle and corpus luteum were monitored and measured. Vaginal discharge and uterine tone were recorded during the rectal palpation. Each animal in the study was sampled for bacteriological examination using endometrial biopsies once a week. Two types of PGF_2α-metabolite patterns were detected: elevated levels during 14 days PP, then decline to the basal level and then a second small elevation at the time of final elimination of the bacteria from the uterus; or elevated levels during first 7 days PP, then decline to the basal level and a second small elevation before the final elimination of bacteria. Endometritis was diagnosed in 5 cows in farm A and in 3 cows in farm B respectively. In farm A, 5 cows out of 10 ovulated during experimental period and in 1 cow cystic ovaries were found. In farm B, 3 cows out of 10 ovulated. In 3 cows cystic ovaries were found. Altogether 40% of cows had their first ovulation during the experimental period. Three cows in farm A and 5 cows in farm B were totally bacteria negative during the experimental period. The most frequent bacteria found were A. pyogenes, Streptococcus spp., E. coli., F. necrophorum and Bacteroides spp. The highest incidence of bacteriological species was found during the first 3 weeks in both farms. All animals were free from bacteria after 5^th week PP in farm A and after 4^th week in farm B respectively. Serum electrolytes and glucose levels were found to be within the reference limits for the cows in both farms. No significant difference was found between farms (p > 0.05). Low phosphorus levels were found in both farms. Significant difference (p < 0.05) was found in BUN levels between farms. In both farms milk acetoacetate values were staying within the reference range given for the used test (<100 μmol/l). The uterine involution and bacterial elimination in the investigated cows could consider as normal but more profound metabolic studies could be needed to find reasons for later resumption of ovarian activity. Some recommendations to changing feeding regimes and strategies should also be given.     

Bacteriological and Histological Investigation of the Postpartum Bovine Uterus in Two Estonian Dairy Herds

Postpartum uterine infections, endometrial histology and resumption of ovarian activity in cows were studied in 2 Estonian dairy herds with different herd sizes, milk yields and management systems. Ten cows at Farm A and 5 cows at Farm B were studied in the experiment. All cows in the study had normal calving performance. Endometrial biopsies for bacteriological and histological examinations were collected once a week starting on the second week postpartum and continuing for 7 weeks postpartum. Milk progesterone samples were collected twice a week during the whole study period. In both herds, the uterine flora contained mainly facultative anaerobic bacteria (Streptococcus spp., E. coli, Staphylococcus spp., Proteus vulgaris). Among obligate anaerobic bacteria only Bacteroides spp. were found. After 7 weeks of collection at farm A, a bacterial uterine flora still persisted in 2 of the cows. At farm B, on the other hand, bacterial elimination was complete after 6 weeks. Presence of inflammatory cells in uterine histology specimens remained higher at the end of collection and resumption of ovarian activity was delayed at farm A. After 7 weeks postpartum, only 6 of the 10 cows at farm A had resumed ovarian cyclicity, while at farm B the first oestrous cycle had occurred in all cows. The study showed that differences regarding uterine infections and their clearance occured between farms and, despite these differences, cows with normal calving performance will effectively recover without any treatment.