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Biomedical subjects

J Fulka

Publications and source records attributed to J Fulka.

At least 91 records · Page 5Linked to original sources
PubMed1986

[Relation between the quality of cattle embryos after thawing and the pregnancy rate after their transfer].

One hundred and forty-two deep-frozen seven days old bovine embryos were, after thawing and stepwise dilution of cryoprotectant, morphologically evaluated under the stereomicroscope. According to the morphology the embryos were divided into four categories as follows: I--fully expanded blastocysts, II--slightly contracted embryos with a minute part of degenerated cells, III--contracted embryos with some degenerated cells, IV--degenerated embryos and those with heavy-damaged zona pellucida, or its complete loss. After surgical transfer of 37 embryos of class I, 16 (43.2%) recipients were pregnant. Transfer of 53 embryos of class II established 20 (37.7%) pregnancies. After transfer of 28 embryos of class III, 10 (35.7%) recipients were pregnant. Twenty four (17%) embryos included in class IV were excluded from transfer. These results indicate that simple morphological evaluation of embryo after freezing and thawing secures relatively objective selection in field conditions. At least this method enables to reveal morphological changes which are not compatible with further development.

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PubMed1985

Inhibition of nuclear maturation in fully grown porcine and mouse oocytes after their fusion with growing porcine oocytes.

Porcine ovarian oocytes, isolated from follicles of 5 mm in diameter (large oocytes), were fused either together or with oocytes isolated from follicles of 0.5 mm in diameter (small oocytes). In giant cells composed of two large oocytes (control) germinal vesicle breakdown (GVBD) occurred and two metaphase I chromosome sets (M I) were observed 24 to 30 h after fusion. By contrast, in giant cells composed of one large and one small porcine oocyte, both germinal vesicles (GVs) remained well conserved after 24-30 h of culture. An identical situation was observed after fusion and cultivation of small porcine and large mouse oocytes isolated from preovulatory follicles. The results demonstrate the presence of inhibiting activity in the ooplasm of small porcine oocytes that prevents nuclear maturation of large porcine and mouse oocytes fused to them. This maturation inhibiting activity can be overcome by preincubating large porcine oocytes for more than 14 h before fusion with small oocytes. During preincubation the ooplasm produces sufficient amount of maturation promoting factor (MPF) to overcome the inhibiting activity present in small porcine oocytes thus inducing GVBD and chromatin condensation both in small and large oocytes.

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PubMed1985

Maturation-inhibiting activity in growing mouse oocytes.

Growing mouse oocytes incompetent to resume meiosis were fused with fully grown immature mouse oocytes and cultured for 20-24 h. In giant cells that developed, two intact germinal vesicles remained well conserved in all cases. We propose that the cytoplasm of growing oocytes possesses a maturation-inhibiting activity which is able to arrest, after fusion, nuclear maturation in fully grown oocytes competent to mature spontaneously.

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PubMed1984

Meiotic competence in vitro of pig oocytes isolated from early antral follicles.

Pig oocytes were isolated from early antral follicles of different sizes and their abilities to resume and complete meiotic maturation in vitro were compared. After 24 h of culture, more than 80% of the oocytes from follicles 0.3-0.7 mm in diameter remained at the germinal vesicle stage, while 66, 94.3 and 100% oocytes from follicles 0.8-1.6, 1.7-2.2 and 3-5 mm in diameter, respectively, completed germinal vesicle breakdown. After 48 h of culture, 35% of the oocytes in the smallest follicle class progressed to prometaphase and only 4% to metaphase I. Of the oocytes from follicles 0.8-1.6 mm in diameter, 23% reached metaphase I and 17.3% metaphase II. About 50 and 76% of the oocytes from follicles 1.8-2.2 mm and 3-5 mm in diameter, respectively, extruded the first polar body. The ability to resume meiosis (i.e. to undergo germinal vesicle breakdown) is reached by porcine oocytes when they approach their full size in antral follicles greater than 0.8 mm in diameter and before they are capable of completing it (i.e. reaching metaphase II). The ability to complete meiotic maturation acquired in antral follicles of about 2 mm in diameter coincided with a significant decrease in the nucleolar transcriptional activity of the oocytes.

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PubMed1983

Blood types of twin cattle after embryo transfer to inseminated recipients.

The blood types, together with erythrocyte and plasma protein types were determined in 10 pairs of twins born after embryo transfer to the contralateral uterine horns of previously inseminated recipients. These estimations were carried out at the age of nine weeks. According to the haemolytic test, most of these pairs of twins had identical blood types, ie, no erythrocyte mosaic could be demonstrated and the blood type corresponded to that of the recipient's calf. In the cases where mosaicism could be demonstrated, the recipient calf's blood type predominated. The reason for this bias remains unclear although the suggestion that the recipient's calf had developed further and was thus able to influence the haematopoietic tissues of its co-twin is worth considering.

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PubMed1983

Nuclear maturation in pig and rabbit oocytes after interspecific fusion.

Porcine ovarian oocytes were fused with either homologous (porcine) or heterologous (rabbit) oocytes, both at different stages of maturation. The maturation-promoting factor (MPF) present in maturing porcine oocytes or ovulated rabbit oocytes induced rapid chromosome condensation of the oocytes with intact germinal vesicles (GVs). In the case of activation of ovulated rabbit oocyte, germinal vesicle breakdown (GVBD) of porcine oocytes was incomplete or did not occur. In the giant cells consisting of two immature porcine oocytes, meiotic maturation proceeded in the same manner as in unfused oocytes. However, in cells derived from fusion of immature porcine and rabbit oocytes, two metaphase groups of chromosomes were observed 6 h after fusion. It may be concluded that GVBD is governed after fusion by the cytoplasm originating from the oocytes of more advanced stages of maturation or from those which mature faster.

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PubMed1982

In-vitro fertilization of zona-free bovine oocytes matured in culture.

Bovine oocytes removed from 3-5 mm follicles were matured in vitro for 22-24 h. The zonae pellucidae were then dissolved by pronase and the eggs were transferred to droplets of preincubated bovine epididymal spermatozoa. Of 575 oocytes, 510 (88.7%) were fertilized and in 261 (45.4%) of them normal male and female pronuclei were present. In the rest male pronucleus formations were arrested or were undetermined (9.7%). Approximately half of the oocytes were fertilized by greater than or equal to 2 spermatozoa. In some of the polyspermic cells male pronuclei of normal size were accompanied by less advanced stages, including sperm heads at the beginning of decondensation. We conclude that a cytoplasmic substance responsible for male pronucleus formation is present in about 50% of randomly selected bovine oocytes.

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PubMed1982

[Transfer of cattle embryos in the induction of twinning].

The superovulation of donors, heifers and cows, was induced by means of gonadotropin PMSG (Antex Leo) in combination with the synthetic prostaglandin analogue--PGF2 alpha (Estrumate, ICI) applied 48 hours later. The response of donors to this treatment was variable. The average number of ovulating follicles from one heifer was fourteen, and the number of embryos to be used was four. In cows the average number of ovulating follicles amounted to six, and on the average three embryos from one donor could be used. Seventy-four embryos were transferred to thirty-seven recipients, into each horn of uterus one embryo. Twenty-six (70%) cows were pregnant, out of this number seventeen (65%) recipients gave birth to twins. In some cases the isolated embryos were kept in the oviduct of female rabbit for 72 hours. It was proved that this deposition did not exert any negative influence on further development of embryos.

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PubMed1981

Culture of horse oocytes in vitro.

Oocytes were removed from follicles 5-30 mm in diameter. The germinal vesicle was present in 69.6% (23/33) of the oocytes at the start of culture, but after 20-24 and 40 h 70.5% (12/17) and 68.2% (43/63) of the oocytes were in metaphase I and metaphase II with first polar body extruded, respectively.

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PubMed1981

Fertilization of rabbit oocytes co-cultured with granulosa cells.

Rabbit ovarian oocytes co-cultured with granulosa cells were transferred for fertilization to the oviducts of recipient does. Oocytes with cumulus cells and membrana granulosa cells were isolated before or 3 h after hCG injection. Granulosa cells did not prevent the resumption of meiosis but the time sequence of nuclear maturation was retarded by about 3 h. When oocytes were isolated from FSH-stimulated ovaries and cultured with only their cumulus cells or with cumulus and granulosa cells of the same origin, non-decondensed sperm heads were detected in about 30% oocytes after fertilization. Culture of FSH-stimulated oocytes with granulosa cells isolated 3 h after hCG injection substantially enhanced the development of male pronuclei to 88.2% and regular cleavage to 85.2% 10 h and 20 h after transfer, respectively. Further improvement was observed if the oocytes and their co-cultured granulosa cells had been exposed to hCG for 3 h.

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PubMed1981

[In vitro maturation of mammalian oocytes].

A review of authors' and published data on maturation of mammalian oocytes in vitro. The following problems are considered: conditions of in vitro oocyte maturation, morphological changes of oocytes during maturation, duration and synchrony of oocyte maturation, RNA and protein synthesis during oocyte maturation, fertilization of oocytes matured in vitro. The oocytes matured in vivo and vitro were shown not to differ morphologically but their ability of subsequent development differed even if meiosis proceeded in the normal way. Upon the resumption of meiosis after the effect of LH in vivo, there appear to occur some substantial changes in the oocytes which are absent during their in vitro maturation.

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PubMed1980

Distribution of proteins labelled during meiotic maturation in rabbit and pig eggs at fertilization.

The fate of proteins formed during meiotic maturation was examined after fertilization. Rabbit ovarian oocytes were labelled in vitro with [3H]lysine and fertilized after transfer to recipients. A significant accumulatin of the label was detected autoradiographically only in fully grown male and female pronuclei. Pig oocytes at the germinal vesicle and metaphase I stages were labelled with [3H]lysine, [3H]methionine or [3H]tryptophan and fertilized. Pronuclei were labelled by all 3 precursors. During cleavage, eggs labelled with [3H]lysine lost the nuclear label by the 4-cell stage. However the [3H]methionine label was present in the cytoplasm and marked in the nuclei at the 4-cell stage, while the [3H]tryptophan label was still clear in 8-cell embryos.

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PubMed1978

Heat and conception rate after synchronisation of oestrus with cloprostenol.

The intensity of induced oestrus in heifers on high and low nutritional planes was graded according to the degree of uterine contraction and cervical relaxation and the volume of oestrous mucus, and correlated with the pregnancy rates after insemination. In the heifers on a high nutritional plane, the heat was more intensely expressed and the conception rates were greater than in the poorly fed animals. In both groups the conception rate was lower in treated heifers than in untreated controls but this difference was minimal on a high plane of nutrition.

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PubMed1978

Breakdown of the germinal vesicle in bovine oocytes cultivated in vitro.

Breakdown of the germinal vesicle (GV) was studied in bovine follicular oocytes cultivated in vitro. The intact GV of control oocytes did not correspond to the findings in porcine oocytes (GV I). Instead it was characterized by a nuclear membrane and a few chromocenters in finely granular nucleoplasm (GV II). After two and three hours of cultivation, GV III predominated (50% and 64% respectively). Faintly-staining chromatin and after a longer interval in the form of filaments also appeared round the chromocenters. After four hours, 35.8% of the oocytes were still at stage GV III but the GV of 46.6% of the oocytes already contained filamentous bivalents (GV IV). After five hours, GV IV (59.7%) was typical, with a less distinct nuclear membrane and condensing bivalents. GV breakdown was completed in 30.4% of the oocytes after five hours of cultivation and in 92.5% after six hours.

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PubMed1976

Breakdown of the germinal vesicle in pig oocytes in vivo and in vitro.

The breakdown of the pig germinal vesicle (GV) was studied in follicular oocytes matured in vivo and in vitro. For better characterization, the whole process was divided into four well-defined stages, based on the chromatin changes, and on nucleolus and nuclear membrane disappearance. In the intact germinal vesicle (GV I) nuclear membrane and nucleolus are clearly visible and chromatin forms a ring or horseshoe around the nucleolus. In the GV II a fre orceinpositive structures (chromocenters) on the nuclear membrane can be detected. For the GV III slightly stained chromatin clumps, localized especially around the nucleolus, and the beginning of strand formation are typical. In the last stage - GV IV - the nuclear membrane is less distinct and the nucleolus disappears completely. Chromatin is seen as an irregular network or as individual bivalents. According to these criteria GV breakdown in vivo was completed in most oocytes between 20 to 24 hours after HCG injection. In culture a similar stage of development was reached between 16 to 20 hours. This difference in the progress of nuclear changes appeared at the beginning of nuclear maturation and remained unchanged throughout the whole period studied.

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PubMed1975

Unimpaired fertilization with thymidine-3H-labelled spermatozoa in the mouse.

Thymidine-3H-labelled spermatozoa were obtained in the sixth week after injection of males with a single or repeated doses of thymidine-3H, in amounts of 3.5 to 50 muCi per gramme body weight. Mouse ova were fertilized in vivo or in vitro by such labelled spermatozoa. It was found by means of autoradiography that heavily labelled spermatozoa compete successfully with non-labelled ones in performing fertilization. The distribution of relative levels of activity in fertilizing spermatozoa was similar to that in the population of inseminated spermatozoa. The early development of ova fertilized by generally labelled spermatozoa (followed up to the first cleavage) was not impaired. It is concluded that spermatozoa labelled with thymidine-3H in their DNA to a level sufficient for autoradiographic detection may be probably used in the studies of the cytology of fertilization without greater precautions regarding possible radiation-induced artefacts.

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