A Multi-Center Study on the Negative Psychological Impact and Associated Factors in Chinese Healthcare Workers 1 Year After the COVID-19 Initial Outbreak

Objectives: The study aimed at analyzing the prevalence of five psychological outcomes (depression, anxiety, stress, post-traumatic stress disorder (PTSD), and suicidal ideation) among Chinese healthcare workers (HCWs), and measured the total possible negative psychological impact 1 year after the COVID-19 initial outbreak. Methods: A cross-sectional nationwide multi-center study was performed between November 2020 and March 2021 in China. A self-report questionnaire was applied, and three psychological scales were used. Binary logistic regression was performed to analyze the risk factors associated with each psychological outcome. Results: The findings demonstrated that the COVID-19 pandemic had a negative psychological impact on HCWs, which was still evident 1 year after the initial outbreak. Nurses showed higher depression and anxiety than other HCWs. Female gender, passive coping, long working hours, having a chronic disease, and experiencing violence, among other factors, were all risk factors for psychological impairment. Conclusion: Developing and promoting programs to improve mental health among HCWs, and identifying those who might need psychological support is still relevant 1 year after the initial outbreak.

[Analysis on cancer incidence and mortality attributed to human papillomavirus infection in China, 2016]

Objective: We aim to evaluate the morbidity and mortality of cancer attributable to human papillomavirus (HPV) infection in China in 2016. Methods: Based on the cancer incidence and mortality rates, national population data, and population attributable fraction (PAF) in China, we calculated the number of incidence and death cases attributed to HPV infection in different areas, age groups, and gender in China in 2016. The standardized incidence and mortality rates for cancer attributed to HPV infection were calculated by using Segi's population. Results: In 2016, a total of 124 772 new cancer cases (6.32 per 100 000) were attributed to HPV infection in China, including 117 118 cases in women and 7 654 cases in men. Of these cancers, cervical cancer was the most common one, followed by anal cancer, oropharyngeal cancer, penile cancer, vaginal cancer, laryngeal cancer, oral cancer, and vulvar cancer. A total of 41 282 (2.03 per 100 000) deaths were attributed to HPV infection, of which 37 417 occurred in women and 3 865 in men. Most deaths were caused by cervical cancer, followed by anal cancer, oropharyngeal cancer, penile cancer, laryngeal cancer, vaginal cancer, oral cancer, and vulvar cancer. The incidence and mortality rates of cervical cancer increased rapidly with age, peaked in age group 50-54 years, then decreased obviously. The morbidity and mortality rates of non-cervical cancer increased with age. The cancer case and death numbers in rural areas (57 089 cases and 19 485 deaths) were lower than those in urban areas (67 683 cases and 21 797 deaths). However, the age-standardized incidence rate (ASIR) and age-standardized mortality rate (ASMR) of cervical cancer were higher in rural areas than in urban areas. There were no significant differences in ASIR and ASMR of non-cervical cancers between urban areas and rural areas. Conclusions: The incidence of cancers attributed to HPV infection in China was lower than the global average, but the number of incidences accounted largely, furthermore there is an increasing trend of morbidity and mortality. The preventions and controls of cervical cancer and male anal cancer are essential to contain the increases in cancer cases and deaths attributed to HPV infection.

[Prognostic evaluation of nutritional indicators in patients with limited-stage small cell lung cancer]

Objective: To explore the effect of nutritional status pre-and during chemoradiotherapy on the prognosis of patients with limited- stage small cell lung cancer (LS-SCLC). Methods: We retrospectively collected medical records of 172 LS-SCLC patients undergoing concurrent chemoradiotherapy in our hospital from 2000 to 2014, with 126 males and 46 females. The data of complete blood count and hepatic and renal function were collected before initial treatment, before radiotherapy, 4 weeks during radiotherapy, and 1 month after complete of treatment. The prognostic nutritional index(PNI)was calculated. Kaplan-Meier method was used to calculate the survival rate. Log-rank test was performed used to compare the survival differences between groups. Multivariate prognostic analysis was performed using Cox regression model. Results: The median overall survival (OS) was 21 months, with median progression-free survival (PFS) of 11 months. At the beginning of treatment, patients with pre-treatment PNI ≥ 53 had significantly superior OS (median 37 vs 15 months, P=0.001) and PFS (median 16 vs 10 months, P=0.017). Patients with pre-treatment hemoglobin ≥140 g/L and <140 g/L had an median OS of 32 months and 17 months (P=0.019), and median PFS of 16 months and 9 months (P=0.040), respectively. During chemoradiation, patients with elevated hemoglobin had similar median OS compared with those had decreased hemoglobin (27 vs 18 months, P=0.063, but superior median PFS (15 vs 9 months, P=0.017). Multivariate analysis revealed that prophylactic cranial irradiation, pre-treatment hemoglobin ≥140 g/L, and pretreatment PNI ≥53 were independent predictors of OS and PFS in patients with LS-SCLC. Conclusion: Pre-treatment nutritional status and the changes of nutritional status during chemoradiotherapy is significantly associated with the prognosis of patients with limited-stage small cell lung cancer. The patients with better pre-treatment nutritional status have a better prognosis.

Dynamic changes of estradiol and progesterone concentrations during in vitro oocyte maturation in cattle

Two culture techniques, an open system using 1.0-ml medium and a covered system using 50-mul droplets of medium covered by paraffin oil, used for in vitro bovine follicular oocyte maturation were compared. Estradiol-17beta (E2) was added to Ham's F-10 medium together with other supplementations. In the absence of oocytes, E2 concentration remained unchanged in the 1.0-ml open system, but it decreased gradually in the 50-mul covered system. In the presence of oocytes, E2 increased significantly in the 1.0-ml open system, but this increase could not be detected in the 50-mul covered system. Progesterone (P4) concentration increased in both systems, but it was much higher in the 1.0-ml culture than in the 50-mul culture. The two culture systems allowed an identical nuclear oocyte maturation rate of 88.6 vs 87.0%, a sperm penetration rate of 54.3 vs 59.6%, and a polyspermy rate of 6.8 vs 11.6% for 1.0-ml and 50-mul systems, respectively. The cleavage rate, however, differed significantly (78.3 vs 41.7% for 1.0-ml and 50-mul systems, respectively). It is concluded that diffusion of steroids into the paraffin oil occurs and may affect the cleavage rate but not the maturation or penetration rate.

A role for MAP kinase in regulating ectodomain shedding of APLP2 in corneal epithelial cells

We previously reported an increased secretion of amyloid precursor-like protein 2 (APLP2) in the healing corneal epithelium. The present study sought to investigate signal transduction pathways involved in APLP2 shedding in vitro. APLP2 was constitutively shed and released into culture medium in SV40-immortalized human corneal epithelial cells as assessed by Western blotting, flow cytometry, and indirect immunofluorescence. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) caused significant increases in APLP2 shedding. This was inhibited by staurosporine and a PKC-epsilon-specific, N-myristoylated peptide inhibitor. Epidermal growth factor (EGF) also induced APLP2 accumulation in culture medium. Basal APLP2 shedding as well as that induced by PMA and EGF was blocked by a mitogen-activated protein kinase (MAPK) kinase inhibitor, U-0126. Our results suggest that MAPK activity accounts for basal as well as PKC- and EGF-induced APLP2 shedding. In addition, PKC-epsilon may be involved in the induction of APLP2 shedding in corneal epithelial cells.

Corneal organ culture model for assessing epithelial responses to surfactants

The main goal of the present study was to investigate the response of cultured bovine corneas to the application of irritant substances and its potential use for predicting ocular irritancy in humans. We hypothesized that chemicals causing eye irritation may induce disruption of epithelial tight junctions and trigger cell stress responses modulated via transcription factors such as AP-1 and NF-kappaB. A simple air-lifted corneal organ culture system was used as an ex vivo model for ocular irritancy test. The effects of two surfactants, sodium dodecyl sulfate (SDS) and benzalkonium chloride (BAK), on corneal epithelial permeability and DNA-binding activity of AP-1 and NF-kappaB were studied in cultured bovine corneas. Both SDS and BAK induced tight junction disruption and increased permeability of corneal epithelium assessed using surface biotinylation in a concentration- and time-dependent manner. An increase in DNA-binding activity measured using electrophoretic mobility shift assay was observed when cultured corneas were treated with surfactants at concentrations causing minimal to mild ocular irritation, indicating epithelial cell stress response. Furthermore, exposure of cultured corneas to SDS or BAK at concentrations causing severe ocular irritancy resulted in a decrease in DNA-binding activity of these transcription factors in epithelial cells. These results indicate that the combination of corneal organ culture and measurements of corneal epithelial permeability and DNA-binding activity of stress-response transcription factors following chemical exposure has the potential to be used as a mechanistically based alternative to in vivo animal testing.

Survival of rabbit limbal stem cell allografts after administration of cyclosporin A

OBJECTIVES

To evaluate the efficacy of systemic or topical administration of cyclosporin A (CsA) after limbal transplantation of stem cell allografts in rabbits.

METHODS

Thirty-six rabbits underwent corneal epithelial debridement and limbal ablation to induce ocular surface disease and were then treated by limbal allograft transplantation. Animals received either systemic CsA (10 mg/kg per day, intramuscularly), 1% CsA eyedrops, or vehicle eyedrops immediately after transplantation and 28 days thereafter. Concentration of CsA in plasma and aqueous humor was determined by fluorescence polarization immunoassay after 4 weeks of therapy. Graft survival was inspected clinically.

RESULTS

Both systemic and topical administration of CsA resulted in a significant prolongation of graft survival. In addition, one of seven of the limbal allografts in either group of systemic and topical CsA survived >60 days on cessation of CsA. There was no significant difference in mean survival time between systemic and topical application, although plasma levels of CsA were significantly higher after systemic administration. However, a significant higher aqueous concentration was found in topical treatment.

CONCLUSIONS

Limbal allografts were stable in maintaining the reconstructed ocular surface under attentive postoperative immunosuppression. Topically administered CsA was as effective as systemic use.

Decrease in corneal sensitivity and change in tear function in dry eye

Our purpose was to investigate the relationship between insufficient tear secretion and decreased corneal sensitivity. We studied 59 patients with dry eye, 15 of whom had Sjögren's syndrome (SS), and 26 healthy subjects. Corneal sensitivity was measured by the esthesiometer of Cochet and Bonnet. Schirmer test with or without anesthesia, tear clearance rate, tear function index, and rose bengal and fluorescein staining were also evaluated. The mean corneal sensitivity of either dry-eye group (4.6 +/- 1.2 and 4.5 +/- 1.2 cm for non-SS and SS dry eye, respectively) was significantly lower than that of the control (5.8 +/- 0.4 cm, p < 0.001). Corneal sensitivity correlated significantly with the Schirmer values with anesthesia and the tear function index in the two dry-eye groups and the control (p < 0.05). There were significant relationships between corneal sensitivity and the rose bengal and fluorescein scores in the three groups (p < 0.05). Hyposecretion of tears in dry eye may lead to pathologic changes in corneal epithelium and a decline in corneal sensitivity. Prompt treatment of dry eye is essential to maintain a normal corneal protective mechanism.

Decreased reflex tearing is associated with lymphocytic infiltration in lacrimal glands

OBJECTIVE

To investigate whether reflex tearing measured by the Schirmer test with nasal stimulation is better correlated with lymphocytic infiltration of the lacrimal gland and is thus a more appropriate test for Sjögren's syndrome (SS).

METHODS

272 patients with dry eye (age 55.5 +/- 13.5 years) with regular Schirmer test results < 10 mm were recruited for the study. They were divided into 2 groups depending on the results of the Schirmer test with nasal stimulation. 24 age and sex matched patients from each group were selected for lacrimal gland biopsy and 10 patients for salivary gland biopsy, and the levels of systemic autoantibodies and degrees of ocular surface staining and lymphocytic infiltration of the lacrimal and salivary glands were compared.

RESULTS

Of the 272 patients, 187 (68.8%) had good reflex tearing (GT) and 85 (31.2%) had poor reflex tearing (PT). There were no significant differences in the age or sex of the 2 groups. Lymphocytic infiltration of the lacrimal gland was observed in 7 GT cases and 22 PT cases out of 24 cases. Lymphocytic infiltration of the salivary gland was also higher in the PT (6 of 10) than the GT group (2 of 10).

CONCLUSION

Evaluation of reflex tearing by the Schirmer test with nasal stimulation identifies 2 groups of patients with dry eye. Those with poor reflex tearing were more likely to have autoantibodies and lymphocytic infiltration of the exocrine glands consistent with SS.

Biopsy of labial salivary glands and lacrimal glands in the diagnosis of Sjögren's syndrome

OBJECTIVE

To determine the diagnostic value in Sjögren's syndrome (SS) of evaluating the presence of focal adenitis in labial salivary gland (LSG) and lacrimal gland (LG) biopsy specimens.

METHODS

We studied 105 cases with suspected SS and performed biopsies prospectively. The diagnostic criteria of Fox, et al were followed. The Chisholm-Mason grading standard and Greenspan focus score were used for evaluation.

RESULTS

Epimyoepithelial islands and severe lymphocyte infiltration with germinal centers were observed only in LG biopsy specimens (5.9 and 3.5%, respectively). The lymphocytic focus scores of LG (2.5 +/- 2.1/4 mm2) were significantly higher than those of LSG specimens (1.3 +/- 1.1/4 mm2) in 23 cases with both biopsy results (p < 0.05). Six of the 32 LSG biopsies were normal while their LG biopsies were significantly higher. Conversely, 5 of the 32 LG biopsies were aided by corresponding LSG biopsies, since in LG biopsies no glandular tissue was obtained. Evaluation of both specimens for the same patient was significantly more effective in diagnosing SS than using either specimen alone (p < 0.01).

CONCLUSION

LG biopsy specimens have a more evident histopathology than LSG biopsy specimens. We recommend that both LSG and LG biopsies be performed in patients with suspected SS to reduce false negative results and improve diagnostic accuracy.

Correlation of tear clearance rate and fluorophotometric assessment of tear turnover

BACKGROUND

The study sought to determine dynamic changes and theoretical bases of a clinical diagnostic test, the tear clearance rate.

METHODS

Thirty four healthy subjects ranging in age from 22 to 84 years underwent examination of tear clearance rate, the Schirmer test with anaesthesia, as well as fluorophotometric measurement of tear turnover, tear volume, and tear flow. By applying 0.5% fluorescein into the conjunctival sac and subsequently measuring colour fades on a Schirmer strip, the tear clearance rate for assessing tear drainage was divided into nine grades. The results of the tear clearance rate were compared with those of the basal tear turnover and tear flow obtained from fluorophotometry.

RESULTS

Significant relations were found between the tear clearance rate and the basal tear turnover or tear flow (r = 0.91 and 0.79, respectively, p = 0.0001). Considering the grades of progression from low to high, each grade of tear clearance rate showed a 12.5% increase in basal tear turnover (3.59%/min) and tear flow (0.38 microliter/min). There was no significant correlation between age and the basal tear turnover, tear volume, tear flow, or the tear clearance rate.

CONCLUSION

The tear clearance rate is proposed as a simple and useful way to estimate basal tear turnover and tear flow, and measure tear drainage indirectly.

Immunohistochemical evidence of neuronal and glial differentiation in retinoblastoma

BACKGROUND

The study sought to investigate the histogenesis of retinoblastoma.

METHODS

One hundred specimens of retinoblastomas were examined along with those of 18 astrocytic gliomas and 15 medulloblastomas to compare similarities of glial differentiation in retinoblastoma and the two types of brain tumour. Employing avidin-biotin immunoperoxidase technique, antibodies were applied against neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP), and S-100 protein (S-100).

RESULTS

Most rosettes and fleurettes, and some undifferentiated cells in retinoblastomas were NSE positive, but GFAP and S-100 negative. GFAP and S-100 positive cells in retinoblastomas were detected mostly in well differentiated glial cells which were interpreted as reactive or non-neoplastic cells. Some of the GFAP and S-100 positive cells in retinoblastomas were defined as tumour cells that resembled neoplastic astrocytes in astrocytic gliomas and medulloblastomas.

CONCLUSION

Retinoblastoma may arise from primitive bipotential or multipotential cells capable of neuronal and glial differentiation.

Extracorporeal development and ultrarapid freezing of human fetal ova

PURPOSE

The present study was performed to culture human fetal ova to determine whether they can be matured and cryopreserved using ultrarapid freezing.

METHODS

Thirty-three pairs of fetal ovaries were obtained from fetuses of 16-20 weeks' gestation following elective abortion. Ovarian tissues were minced into approximately 1-mm sizes and cultured in Waymouth media either before or after ultrarapid freezing. The Waymouth medium was supplemented with 15% (v/v) fetal bovine serum, 0.03 IU/ml FSH and 35 ng/ml insulin. The tissue was cultured at 37 degrees C in 5% CO2 in air for 5-25 days in Falcon dishes and 30-40 days in Costar Transwell-COL membranes prior to induction of final maturation in the presence of LH and human follicular fluid. Minced tissues were also frozen by ultrarapid freezing in M199 with 4.2 M dimethylsulfoxide (DMSO) and 0.35 M sucrose and plunged directly into liquid nitrogen. For thawing, the straws were plunged into a 37 degrees C water bath for 5 s. The contents were then expelled and diluted 1:5 with thawing medium containing 0.42 M sucrose. After washing the thawed tissues were cultured as described for the fresh tissues.

RESULTS

Patches of monolayer consisting of fibroblasts had formed within 2-3 days of culture of fresh tissues. After 1 week of culture, follicles separated out from the ovarian tissue but remained attached to the monolayer. The maximal number of follicles separating out from the tissue appeared about 1 week after initiating the culture (154 follicles per 10 fields at Day 5 and 61 and Day 25). After 40 days of culture in Costar dishes, 34% of the ova reached a diameter of more than 80 microns, which was significantly higher than at the beginning of culture (6%; P < 0.05). Among these ova, 34% were found to be surrounded by the zona pellucida, which was not observed at the beginning of culture. Following induction of final maturation, extrusion of the first polar body was noted in 25% of ova grown in Costar dishes for 40 days. Twelve percent of the oocytes showed the first polar body when they were grown in Costar dishes for less than 30 days. For frozen-thawed tissues, 14% of minced ovarian tissues displayed central necrosis immediately after thawing. Following digestion and Trypan blue staining, 75% of ova and 85% of somatic cells survived ultrapid freezing. Nineteen percent of the ova which have been cultured as described for fresh tissues displayed extrusion of the first polar body, comparing favorably with the 25% maturation rate observed with the fresh tissue (P > 0.05).

CONCLUSION

This study demonstrates that morphologically normal, mature human ova can be obtained from primordial follicles in vitro development. Using a simple, quick ultrarapid freezing method, human fetal ova can be cryopreserved in the form of minced tissue without significantly compromising their ability to grow in vitro.

Tear function index. A new measure of dry eye

OBJECTIVE

To develop an efficient way to evaluate tear dynamics clinically.

PARTICIPANTS

Three hundred fifty-two patients with dry eye, 64 of whom had Sjögren syndrome, and 55 normal subjects.

DESIGN

Because various forces that affect tear drainage are reflected in the values of the Schirmer test with anesthesia and the tear clearance rate, we introduced a new measure of tear dynamics, the tear function index, which is the value obtained from dividing the value of the Schirmer test with anesthesia by the tear clearance rate.

RESULTS

The tear function index was more specific (91.8%) and sensitive (78.9%) in diagnosing dry eye associated with Sjögren syndrome than was the Schirmer or tear clearance rate test alone. Tear function indexes below 96 were consistent with dry eye and those below 34 were seen primarily in patients with Sjögren syndrome.

CONCLUSIONS

The tear function index offers a new method to evaluate tear production with the Schirmer test, introduces an extended way to measure tear flow combining with tear drainage, and gives a practical measure to diagnose dry eye.

Sex-related differences in developmental rates of bovine embryos produced and cultured in vitro

The classical concept of sex determination in mammals is that a Y chromosomal gene controls the development of the indifferent gonad into a testis. Subsequent divergence of sexual phenotypes is secondary to this gonadal determination. The most likely candidate gene is SRY (sex-determining region Y) in humans, and Sry in mouse. However, several lines of evidence indicate that sexual dimorphism occurs even before the indifferent gonad appears. Here we present evidence that bovine male embryos generally develop to more advanced stages than do females during the first 8 days after insemination in vitro. Corresponding relationships between both cell numbers and mitotic indices and sex were also seen. Although it is not clear whether this phenomenon involves factors originating before or after fertilization, these findings suggest that sex-related gene expression affects the development of embryos soon after activation of the embryonic genome and well before gonadal differentiation.

Application of in vitro fertilisation techniques to obtain calves from valuable cows after slaughter

The ovaries of two infertile cows of high breeding value were recovered after slaughter, and a total of 222 oocytes were obtained. Of these, 156 were classified as of good or fair quality and were subjected to in vitro maturation, in vitro fertilisation (using frozen semen from three bulls of high breeding value) and in vitro culture procedures. After eight days, 27 embryos were obtained, of which 13 were transferred fresh, and 14 were frozen. Three recipients of fresh embryos became pregnant; two calved and one aborted at four months. One of eight recipients of frozen-thawed embryos became pregnant but aborted at three months.

Development and viability of bovine embryos derived from oocytes matured and fertilized in vitro and co-cultured with bovine oviducal epithelial cells

A co-culture system using a suspension of detached bovine oviducal epithelial cells (BOEC) has been developed as an effective culture method for supporting the development of bovine embryos derived from oocytes matured and fertilized in vitro. Four commercially available culture media (Waymouth's, Ham's F-10, TCM 199 and Ménézo's B2) supplemented with 10% oestrous cow serum, and a modified Tyrode's medium (TALP) supplemented with 0.6% bovine serum albumin were used. Ménézo's B2 resulted in the highest percentages of total uncleaved presumptive zygotes, and of the cleaved zygotes that reached at least the morula stage (31-46% and 66-74%, respectively). The embryos produced in vitro in B2 with BOEC resembled embryos produced in vivo with regard to numbers of cells (averaging 45.4 in morulae, 101.5 in blastocysts, 174.7 in hatching blastocysts and 195.9 in hatched blastocysts), rate of development (hatching on Day 8-9 of culture in vitro), rate of hatching (66% of cleaved zygotes) and pregnancy rates (63%) resulting from the transcervical transfer of selected embryos.

The sex ratios of bovine embryos produced in vivo and in vitro

The male:female ratio of developing bovine embryos produced and allowed to develop in vitro and in vivo was determined retrospectively from the cytogenetic analysis of 804 embyos. The overall male:female ratio of the 307 (38%) embryos that could be sexed was 162 (52.8%):145 (47.2%) and did not differ (P>0.05) from the expected 1:1 ratio. Among premorula stage embryos produced in vivo (n = 66) and in vitro (n = 30), the ratios were 1.2:1 and 0.76:1, respectively. Among morulae and blastocysts produced in vivo (n = 74), produced and cultured in vitro (n = 106, and produced in vitro and cultured in vivo (n = 31), the ratios were 1.11:1, 1.3:1 and 0.94:1, respectively, none of which differed significantly from 1:1. There was no difference (P>0.05) in the number of cells or mitotic index between male and female morulae and blastocyst, respectively.

Birth of a calf from bovine oocytes matured and fertilized in vitro

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Cytogenetic study of parthenogenetically activated bovine oocytes matured in vivo and in vitro

Three experiments were performed to evaluate the potential for parthenogenetic activation of bovine oocytes in in vitro fertilization systems and to determine the chromosome complement of the resulting parthenogenotes. In the first experiment, immature oocytes from slaughtered cattles were matured in vitro in Defined Medium (DM) for 24 h to simulate in vitro fertilization conditions. Subsequently, a portion was fixed, and the remainder were transferred to rabbit oviducts. Oocytes were then cultured for 6-8 h or for 24 h with Colcemid present during the last 6 to 8 h and fixed on slides and examined. In the second experiment, mature oocytes were collected from the preovulatory follicles, and the oocytes were subjected to the same culture as in experiment I. In the third experiment, oocytes were treated as in experiment II, except that instead of transfer to rabbit oviducts, they were cultured an additional 48 h in vitro. In experiment I, 131 oocytes were fixed after culture in DM. Of the 79 oocytes analyzed in the pre-rabbit group, 71 (90%) were at the second meiotic metaphase (MII), and 8 (10%) were at pre-MII stage; none were activated. After transfer to rabbits, 291 were fixed. Of these, 80 were analyzed; 37 (46.3%) were MII, 7 (8.6%) were pre-MII, and 36 (45%) were activated. Of the 36 activated oocytes, 26 (72.2%) were haploid, 4 (11.1%) were diploid, 1 (12.8%) was tetraploid, and 5 (13.8%) were in the process of endoreduplication. In experiment II, 51 oocytes were fixed after culture in DM of which 36 (70.6%) could be analyzed; 30 (83.3%) were MII, and 6 (16.7%) were pre-MII. After culture in the rabbit, 68 were fixed of which 27 (39.7%) could be analyzed. Of these 27, 20 (74.1%) were MII, and 7 (25.9%) were activated; 6 were haploid, and 1 was endoreduplicating. In experiment III, 30 oocytes were fixed at the end of the culture period; only 10 could be analyzed of which 8 (80%) were MII and 2 (20%) were pre-MII. In all, 46% of in vitro and 26% of in vivo matured oocytes were activated, based on chromosomal analysis. Of those activated, the majority (74.4%) were haploid, suggesting that activation occurs at or after completion of MII. Endoreduplication appears to be one of the mechanisms leading to the formation of diploid and polyploid parthenogenotes.

Scanning electron microscopy of in vitro fertilization in cattle

Cumulus-oocyte complexes were collected from cows at an abattoir by aspiration from small (1-6 mm) follicles. The complexes were matured in vitro for 28 h. Subsequently, the cumulus cells and the zona pellucida were removed by enzyme treatment in a proportion of the complexes (zona-free ova). Both cumulus-enclosed and zona-free ova were inseminated in vitro and processed for scanning electron microscopy after different periods of culture. In the cumulus-enclosed ova the number of spermatozoa attached to and penetrating into the cumulus investment increased with increasing culture time. Practically all spermatozoa displayed intact acrosomes. In the zona-free ova clusters of spermatozoa attached to the ovum surface, and at 5 h a proportion of the spermatozoa had undergone the acrosome reaction, and their internalization into the ooplasma was initiated. The acrosome reaction was characterized by an increasing fenestration of the membrane coverings of the acrosomal region of the sperm head. During the sperm head internalization, where the ovum microvilli appeared to contact especially the equatorial segment and the postacrosomal region, the sperm head gradually disappeared from the ovum surface, and the microvilli at the site of internalization became more bulbous. Simultaneous abstriction of the second polar body was seen in some ova.

Ultrastructural abnormalities of in vitro fertilization of in vitro matured bovine oocytes

Cumulus-oocyte complexes collected from cows at an abattoir by aspiration from small (1-6 mm) antral follicles were matured and inseminated in vitro. At different time intervals after insemination the ova were processed for transmission electron microscopy. Up to and including 6 h after insemination all ova were unfertilized, and their cortical granules were more or less clustered. At 6 h acrosome reaction of spermatozoa was observed on the surface of the zona pellucida. At 8 h the first fertilized ovum appeared and the first fully developed spherical pronucleus was observed, at 20 h the first apposition of pronuclei was seen, and at 40 h divisions were ongoing or completed. More than one third of the fertilized ova showed polyspermic penetration of the zona pellucida, and in most of these ova different developmental stages of supernumerary pronucleus formation were observed in the ooplasm. Abnormal cortical granule release was seen in approximately half of the fertilized ova, and it was more frequent in ova with polyspermic as opposed to monospermic penetration of the zona pellucida.

A detailed analysis of early events during in-vitro fertilization of bovine follicular oocytes

Bovine follicular oocytes collected at slaughter were matured and fertilized in vitro with in-vitro capacitated spermatozoa. Analysis of 621 penetrated ova fixed at various times after in-vitro insemination led to definition of 6 stages of early development. A time sequence for sperm penetration, sperm head decondensation, male pronucleus formation, the activation of second meiotic division, female chromosome decondensation and pronucleus development was established. First sperm penetration into the ooplasm was recorded 6 h after insemination; 1-2 h was required for the sperm head to decondense and another 4-6 h to develop into the opposing pronucleus stage. Synkaryosis and first cleavage occurred 28 h after fertilization. Examination of the early stages revealed four types of abnormalities, i.e. polyspermy, polygyny, asynchrony between male and female pronucleus development, and preactivation of cytokinesis.

Pregnancy resulting from cattle oocytes matured and fertilized in vitro

Follicular oocytes (n = 81) collected from cattle at a local slaughterhouse were matured and fertilized in vitro. Of 27 ova 19 (70%) were penetrated by spermatozoa and 40/54 (74%) inseminated ova transferred surgically to the oviducts of a synchronized heifer were recovered by non-surgical flushing of the uterine horns 6 days later. Of the 40 ova 15 (38%) were at the morula, early blastocyst or diminutive morula stages. Culture in vitro sustained further development of all embryos and 9 were expanding or expanded blastocysts. One pregnancy resulted from non-surgical transfer of 2 blastocysts. The results demonstrate that immature oocytes from cattle can be matured and fertilized in vitro, subsequently develop to the blastocyst stage, and develop into a normal pregnancy after non-surgical transfer.

In vivo development of in vitro fertilized bovine oocytes matured in vivo versus in vitro

In vivo developmental potentials of in vivo and in vitro matured oocytes fertilized in vitro were assessed in cattle. One-cell stages produced from in vivo matured oocytes developed into a pregnancy when transferred to the ampulla part of oviducts of synchronized heifers. In vitro matured oocytes achieved high penetration and cleavage rates but did not develop into pregnancies when transferred to synchronized heifers.

Ultrastructure of the final nuclear maturation of bovine oocytes in vitro

Cumulus-oocyte complexes were obtained from cow ovaries by aspiration from small (1-6 mm in diameter) antral follicles after slaughter. Complexes with a compact multilayered cumulus investment were cultured and subsequently processed for electron microscopy after various periods of culture. By morphological criteria the oocytes could be divided into the following sequence of meiotic stages. The oocyte nucleus I stage was characterized by a spherical nucleus located peripherally in the ooplasm while undulation of the nuclear envelope and initial chromatin condensation was seen at the oocyte nucleus II stage. The oocyte nucleus breakdown stage was characterized by formation of long slender projections from the nuclear envelope in which the envelope doubled back on itself, appearance of dense areas and haphazardly oriented microtubules in the nucleus, marked condensation of the chromatin, and dissolution of the nuclear envelope into irregular vesicles and tubules. The condensed chromatin I stage was characterized by the location of condensed chromatin configuration and uniformly oriented microtubules in a dense area peripherally in the ooplasm while the final condensed chromatin II stage was characterized by a gradual invasion of condensed chromatin configurations into a dense area combined with the presence of the first polar body in the perivitelline space.

Ultrastructure of in-vitro oocyte maturation in cattle

Cumulus-oocyte complexes were collected from cows at an abattoir by aspiration from small (1-6 mm) antral follicles. After different periods of culture the complexes were processed for electron microscopy. Cumulus expansion occurred at 12-18 h of culture and concomitantly enlargement of cumulus cell projections in the perivitelline space was seen. At 48 h the innermost cumulus cells flattened and adhered tightly to the zona pellucida. In the oocyte the following changes occurred: at 0-3 h of culture the perivitelline space developed; at 3-12 h disconnection of the junctions between cumulus cell projections and the oolemma, and the concomitant breakdown of the nucleus was observed; at 12-18 h the mitochondria moved from a peripheral location to a more even spatial distribution and the Golgi complexes decreased in size; at approximately 18 h the smooth endoplasmic reticulum formed large aggregates surrounded by mitochondria; at 18-21 h the first polar body was abstricted; at 24-40 h the cortical granules spread; at 30-40 h the polar body degenerated in some specimens; at 40-48 h the perivitelline space decreased in size; and at 48 h one oocyte was in the process of fragmentation. It is concluded that nuclear and cytoplasmic oocyte maturation is simulated in vitro. However, certain deviations were noticed compared to in-vivo maturation.

Nuclear and cytoplasmic maturation of bovine oocytes cultured with dbc AMP, FSH and hCG

The present investigation was undertaken to study the effect of addition of dbc AMP on bovine oocyte maturation and fertilization in vitro. The bovine oocytes isolated from 2–8 mm follicles were cultured for 26 h in TCM-199. The maturation rate (71.4 %) did not significantly increase after supplementation of the culture medium with dbc AMP (86.3 %.) or FSH + hCG (86.3 %). The in vitro fertilization rate of oocytes based on sperm penetration and presence of sperm tail in the ooplasm increased significantly in the dbc AMP (34.7 %) and the dbc AMP + FSH + hCG (33.9 %) treated groups when compared with untreated controls (17.9 %). However, dbc AMP treated oocytes were not able to secure the formation of male pronucleus 20 h after in vitro fertilization, while in oocytes matured in dbc AMP free medium both pronuclei were present in approximately 15 % of the penetrated oocytes. Also, the sperm head decondensation was blocked or slowed down by the dbc AMP treatment. It is concluded (1) that dbc AMP may improve the condition for the interaction of oocytes with spermatozoa, and (2) that the ooplasm of such dbc AMP treated oocytes apparently is not able to decandense the sperm head and transform it to the male pronucleus.

Chronological changes of bovine follicular oocyte maturation in vitro

Chronological changes of bovine follicular cumulus-oocyte-complexesi were studied after in vitro maturation over a period of 48 h. According to their thickness and compactness of cumulus investments they were classified into 4 groups and cultured in enriched Ham’s F-10 medium with or without human chorionic gonadotrophin (hCG) and estradiolbenzoate (EB) for 0, 6, 12, 18, 21, 24, 27, 30 and 48 h. Representative samples were taken at each time interval for evaluation of nuclear maturation stages, ooplasm quality and size of the peri vitelline space (PVS). The results showed that oocyte nuclear breakdown (ONBD) required 6 to 12 h culture, and the peak of the first polar abstriction occurred at 24 h. The culture period required for ONBD and abstraction of the first polar body were related to the thickness and compactness of cumulus investments with and approximately 6 h delay in heavily compacted complexes. Ooplasm quality evaluation failed to show a clear trend, but the PVS increased in size from 0 h to 30 h and then, retracted again from 30 to 48 h. The overall maturation rate in the presence of hCG and EB was 79.1 %, and a substantial proportion (68.8 %) of nude or partially covered oocytes reached metaphase II stage. In the presence of hCG and EB no block at either metaphase I or at anaphase-telophase I was observed. In the absence of hCG and EB the percentage of oocytes reaching metaphase II was much lower (48.6%) in comparison with oocytes matured in the presence of these hormones (79.1 %). It was concluded a very high proportion of slaughterhouse oocytes could be matured in vitro and that the cumulus investments and addition of certain hormones affected the maturation rate.