Cow body condition affects the hormonal release of ovarian cells and their responses to gonadotropic and metabolic hormones.

The body condition score (BCS) of cows affects their reproductive efficiency, but the underlying mechanism is unclear. We examined the effect of BCS on the basic ovarian cell functions and their responses to gonadotropic and metabolic hormones. We isolated ovarian cells from cows with a tendency toward emaciation (BCS2) and those with an average body condition (BCS3), and we compared their hormonal release and responses to FSH, leptin, ghrelin, and neuropeptide Y (NPY) added at doses of 0, 1, 10, or 100 ng/mL. Progesterone, testosterone, estradiol, and insulin-like growth factor I (IGF-I) release were evaluated by RIA. No differences were found in progesterone or testosterone release between BCS2 and BCS3 cells; however, ovarian cells from BCS2 cows released more estradiol and IGF-I than cells from BCS3 cows. FSH, ghrelin, and NPY promoted progesterone release in BCS2 cells but had no stimulatory or inhibitory effect on BCS3 cells. In contrast, leptin promoted progesterone release in BCS3 cells and inhibited progesterone release in BCS2 cells. FSH also promoted testosterone release in both BCS2 and BCS3 cells but inhibited progesterone at a low dose in BCS3 cells. Leptin inhibited testosterone release in BCS3 cells but not in BCS2 cells. Estradiol release was promoted by leptin and ghrelin in BCS3 cells; however, it was unaffected by leptin and inhibited by ghrelin in BCS2 cells. IGF-I production was promoted by FSH and inhibited by leptin in both groups. Ghrelin suppressed IGF-I release in BCS2 cells and increased IGF-I release in BCS3 cells. NPY promoted IGF-I release in BCS2 cells but not in BCS3 cells. Our results demonstrate the effects of BCS on ovarian cell estradiol and IGF-I (but not progesterone or testosterone) release, as well as on the responses of ovarian cells to FSH, leptin, ghrelin, and NPY.

Quality of Pinzgau bull spermatozoa following different periods of cryostorage.

The aim of this work was to examine the influence of cryostorage duration of Pinzgau bull's insemination doses (IDs) on some sperm traits. The IDs were frozen by a slow freezing method and stored in liquid nitrogen for different periods: less than 8 years (group 1), 8-13 years (group 2) and 14-18 years (group 3). Motility (CASA), pathological sperm rate (Giemsa staining), apoptotic (Yo-Pro-1-positive) and necrotic (propidium iodide-positive) cell occurrence and fertilizing ability (penetration/fertilization test) of spermatozoa were evaluated post-thaw. The average post-thaw sperm motility in all examined groups was over 40%. No significant influence of storage length either on the sperm total motility or progressive movement was revealed. In each tested group the average rate of malformed spermatozoa did not exceed 20%. No effect of cryostorage length on the occurrence of apoptotic or necrotic sperm was noted. Similarly, penetrating/fertilizing ability of sperm did not differ among the groups, excepting differences in the rate of pronuclei (PN) formation. In group 1, 72.9% of eggs showed two visible PN following 20 h incubation with sperm, whilst in groups 2 and 3 only 67 and 54.5% of zygotes, respectively, had both PN at this time. These results revealed no influence of storage time on the bull spermatozoa in all parameters excepting the rate of PN formation. As high inter-male variability was observed in the susceptibility of bull sperm to cryostorage, individual differences should be taken into account when semen from individual bulls is to be stored for a long time.

Ultrastructure of Cell Organelles in Pre-implantation Embryos from Cows with Different Body Condition Score.

Morphology of important cell organelles (mitochondria, lipid droplets, vacuoles, inclusion bodies and apoptotic bodies) in embryos derived from cows with different body condition score (BCS) was analysed by transmission electron microscopy (TEM). Embryos were recovered on 7th day after the insemination by a standard non-surgical flushing of the uterine horns from superovulated Holstein Friesian cows with BCS 2, 3, 4 and 5. Thereafter, the good quality blastocysts were processed for TEM. The electronograms were evaluated by stereological analysis. The relative volume of lipid droplets in BCS4 and BCS5 embryos increased significantly (18.53 and 22.40%) when compared to BCS3 embryos (5.46%). In the embryos from the BCS4 or BCS5 cows, we observed different morphological patterns of mitochondria, as well as the mitochondria containing vacuoles. BCS4 and BCS5 embryo cell nuclei showed the structure typical for low transcription activity (none or very few reticular nucleoli); also dilated inter-cellular spaces were often observed in these embryos. In conclusion, differences in the ultrastructural morphology of embryos from over-conditioned cows (BCS4 and BCS5), particularly the higher lipid content in the cytoplasm, can be a marker of their low quality, and this fact can be a contributing factor to subfertility in over-conditioned cows.

Quality of preimplantation embryos recovered in vivo from dairy cows in relation to their body condition.

This study examined the impact of cow body condition on the quality of bovine preimplantation embryos. The embryos (n = 107) were flushed from dairy cows and classified according to a five-point scale body condition score (BCS2 n = 17; BCS3 n = 31; BCS4 n = 11) on the 7th day after insemination and then analyzed for development, dead cell index (DCI), cell number and actin cytoskeleton quality. The highest embryo recovery rate (P < 0.05) was recorded in the BCS3 group and the lowest in the BCS4 group. More transferable (morula, blastocyst) embryos were obtained from the BCS4 cows (79%), compared with the BCS2 (64%) or BCS3 (63%) animals. However, cell numbers were higher in the BCS2 and BCS3 groups (P < 0.05) compared with the BCS4 embryos. Conversely, the DCI was lowest in the BCS2 (3.88%; P < 0.05) and highest in the BCS4 (6.56%) embryos. The proportion of embryos with the best actin quality (grade I) was higher in the BCS2 and BCS3 cows compared with the BCS4 group. Almost 25% of all embryos showed fragmented morphology and a higher DCI (5.65%) than normal morulas (1.76%). More fragmented embryos were revealed in the BCS2 (28.6%) and BCS4 (31.25%) groups, and less (19.15%) in the BCS3 group. The cell numbers in such embryos were lower in the BCS4 (22.57) than in the BCS2 (46.25) or BCS3 (42.4) groups. In conclusion, the body condition of dairy cows affects the quality of preimplantation embryos. A BCS over 3.0 resulted in a higher incidence of poor (fragmented) embryos.

Histopathological alterations in the antral ovarian follicles in dairy cows with a tendency to emaciation.

The aim of the study was to define interrelationships between histopathological alterations in ovarian antral follicles and body condition in dairy cows with a tendency to emaciation (BCS 1 and 2) compared with dairy cows with normal body condition (BCS 3). The ovaries were recovered from slaughtered cyclic dairy cows (at the luteal phase of the cycle) of Czech Fleckvieh and Holstein breeds at different times of the post-partum period. The animals were estimated as belonging to certain grade of body condition score (BCS) according to a 5-point scale. Only dairy cows with BCS1 (emaciation; n=6), BCS2 (tendency to emaciation; n=5) and BCS3 (optimal body condition status; n=6) were available for the experiment. The ovarian samples were embedded into Technovit 7100 resin; the tissue sections were stained with buffered basic fuchsine with toluidine blue. For acidic mucopolysaccharides (aMPS) a combination of PAS-technique with Alcian blue was used. Histological analysis showed that emaciation was associated with an increased occurrence of late (cystic) and luteinization-related atresia in granulosa and theca cells and increased levels of aMPS in small atretic follicles. Our observations indicate that dairy cows with a tendency to emaciation (BCS 2) or emaciated (BCS 1) have elevated occurrence of late atresia and atresia with luteinization, while initial atresia is less. This expands our basic knowledge of ovarian histopathology providing new insight into the association of antral follicle atresia and body condition status in dairy cows.

Morphology of testes from transgenic rabbits: histological and ultrastructural aspects.

The aim of this study was to compare morphological characteristics of testes from transgenic (the WAP-hFVIII gene) and non-transgenic rabbits with emphasis on the histological and ultrastructural aspects. Samples of testes from both groups were fixed and embedded into Durcupan ACM for transmission electron microscopy. For histological analysis, semi-thin toluidine blue-stained sections were evaluated under a Jenaval light microscope. Male fertility was tested based on egg fecundity and blastocyst yield; transgene transmission was proved using PCR assay. Spermatogenesis in rabbit testes had not been destroyed both in transgenic and non-transgenic rabbits. No significant differences were found in the occurrence of individual cell organelles of the Sertoli cells in transgenic and non-transgenic rabbits. The ultrastructure of Leydig cells in testes of transgenic and non-transgenic rabbits was rather similar. No differences in the occurrence of individual organelles of Leydig cells between transgenic and non-transgenic males were found. These results were in concert with fertilizing capacity of transgenic spermatozoa. The presented status of organelles in this study indicates functional activity of the analysed cells.

Several aspects of animal embryo cryopreservation: anti-freeze protein (AFP) as a potential cryoprotectant.

With the development of embryo technologies, such as in vitro fertilization, cloning and transgenesis, cryopreservation of mammalian gametes and embryos has acquired a particular interest. Despite a certain success, various cryopreservation techniques often cause significant morphological and biochemical alterations, which lead to the disruption of cell organelles, cytoskeleton damages, cell death and loss of embryo viability. Ultrastructural studies confirm high sensitivity of the cell membrane and organelle membrane to freezing and thawing. It was found that many substances with low molecular weights have a protective action against cold-induced damage. In this concern, an anti-freeze protein (AFP) and anti-freeze glycoproteins (AFGPs), which occur at extremely high concentrations in fish that live in Arctic waters and protect them against freezing, may be of potential interest for cryostorage of animal embryos at ultra-low temperatures. This mini-review briefly describes several models of AFP/AFGP action to preserve cells against chilling-induced damages and indicates several ways to improve post-thaw developmental potential of the embryo.

[Morphological-functional characteristic of periarticular tissue after total hip arthroplasty: histological, cytochemical and electron microscopy aspects]. / Morfologicko-funkcná charakteristika periartikulárneho tkaniva po endoprotéze bedrového klbu: histologické, cytochemické a elektrónmikroskopické aspekty.

PURPOSE OF THE STUDY Analysis of the tissue harvested around the total hip replacement isolated from re-operated patients in order to: (1) characterize complexity of structural processes developing in the region of the total hip replacement and, (2) to define the role and significance of histological structures of this tissue, mainly in relation to implant loosening, from the viewpoint of formal and causal pathogenesis. MATERIAL AND METHODS Biopsied material isolated from periarticular tissue of re-operated patients (n=19) after THR was analyzed using the methods of light optic, fluorescent (TUNEL), and transmission electron microscopy. RESULTS Histological analysis revealed fibroproliferaive processes and epithelioid granulomatosis cell reaction around the implant with the formation of giant multinuclear syncythial (osteoclastlike) structures as a response to foreign bodies. These structures phagocyte fragments of foreign material (polyethylene particles from the implant, cement fragments). All the used methods revealed a range of regressive changes in the layers of foreign microparticles (inside giant multinuclear cells) typical of fibrinoid necrosis in collagen fibres and apoptosis. In certain cases, progressive changes as chondroid and synovial differentiation (metaplasia) were observed. DISCUSSION Total hip replacement, despite all positive aspects for patients, may cause permanent inflammatory processes in its surrounding. This may result in an extensive fibroproduction of a differently thick layer of connective tissue around the implant. An important factor of loosening of THR is probably osteoclastic resorption in the area of "bone-implant" interface, as a result of the interaction between the inflammatory mechanisms around the implant. CONCLUSION In the postoperative period, there occur fibroproliferative changes in the periarticular tissue and large population of multinuclear cells. In our view, these cells play a role in the production of wear particles from the implant and microparticles of bone tissues and bone cement. Fibroproliferative process may be considered as an immune response to the implanted foreign material.

Alteration in ultrastructural morphology of bovine embryos following subzonal microinjection of bovine viral diarrhea virus (BVDV).

The aim of the present study was to evaluate the development and ultrastructure of preimplantation bovine embryos that were exposed to bovine viral diarrhea virus (BVDV) in vitro. The embryos were recovered from superovulated and fertilized Holstein-Friesian donor cows on day 6 of the estrous cycle. Compact morulae were microinjected with 20 pl of BVDV suspension (10(5.16) TCID(50)/ml viral stock diluted 1:4) under the zona pellucida (ZP), then washed in SOF medium and cultured for 24-48 h. Embryos were evaluated for developmental stages and then processed immunocytochemically for the presence of viral particles, using fluorescent anti-BVDV-FITC conjugate. Ultrastructure of cellular organelles was analysed by transmission electron microscopy (TEM).After microinjection of BVDV under the ZP, significantly more (p<0.001) embryos (83.33%) were arrested at the morula stage compared with the intact control (30.33%). Immunocytochemical analysis localized the BVDV-FITC signal inside the microinjected embryos. TEM revealed: (i) the presence of virus-like particles in the dilated endoplasmic reticulum and in cytoplasmic vacuoles of the trophoblast and embryoblast cells; (ii) the loss of microarchitecture: and (iii) abnormal disintegrated nuclei, which lacked reticular structure and the heterochromatin area. In all, the embryo nuclear structure was altered and the microarchitecture of the nucleolus had disappeared when compared with the nuclei from control embryos. Dilatation of the intercellular space and the loss of the intercellular gap junctions were often observed in bovine BVDV-exposed embryos. These findings provide evidence for the adverse effect of BVDV virus on the development of bovine embryos, which is related to irreversible changes in the ultrastructure of cell organelles.

Development and viability of bovine preimplantation embryos after the in vitro infection with bovine herpesvirus-1 (BHV-1): immunocytochemical and ultrastructural studies.

The aim of our study was to examine whether: (1) the exposure of bovine embryos to the BHV-1 virus in vitro can compromise their further development and alter the ultrastructural morphology of cellular organelles; (2) whether the zona pellucida (ZP) can be a barrier protecting embryos against infection; and (3) whether washing with trypsin after viral exposure can prevent virus penetration inside the embryo and subsequent virus-induced damages. The embryos were recovered from superovulated Holstein-Friesian donor cows on day 6 of the estrous cycle. Only compact morulas or early blastocysts were selected for experiments with virus incubation. We used the embryos either with intact ZP (either with or without trypsin washing) or embryos in which the ZP barrier was avoided by using the microinjection of a BHV-1 suspension under the ZP. ZP-intact embryos (n = 153) were exposed to BHV-1 at 10(6.16) TCID(50)/ml for 60 min, then washed in trypsin according to IETS guidelines and postincubated in synthetic oviduct fluid (SOF) medium for 48 h. Some of the embryos (n = 36) were microinjected with 20 pl of BHV-1 suspension under the ZP, the embryos were washed in SOF medium and cultured for 48 h. Embryo development was evaluated by morphological inspection, the presence of viral particles was determined both immunocytochemically, using fluorescent anti-IBR-FITC conjugate and by transmission electron microscopy (TEM) on the basis of the ultrastructure of the cellular organelles. It was found that BHV-1 exposure impairs embryo development to higher preimplantation stages independent of the presence of the ZP or the trypsin treatment step, as most of the embryos were arrested at the morula stage when compared with the control. Immunofluorescence analysis confirmed the presence of BHV-1 particles in about 75% of embryos that were passed through the trypsin treatment and in all the BHV-1-microinjected embryos. Ultrastructural analysis, using TEM, revealed the presence of virus-like particles inside the BHV-1-exposed embryos, where the trypsin washing step was omitted. Conversely, in trypsin-treated BHV-1-exposed embryos, TEM detected only the envelope-free virus-like particles adhered to pores of the ZP. The embryos that were microinjected with BHV-1 suspension showed the presence of BHV-1 particles, as well as ultrastructural alterations in cell organelles. Taken together these findings may suggest that BHV-1 infection compromises preimplantation development of bovine embryos in vitro and therefore the ZP may not be enough on its own to prevent virus-induced damage, unless it is not accompanied with trypsin washing.

The effect of hyperthermia in vitro on vitality of rabbit preimplantation embryos.

The aim of our study was to test the influence of short exposure (6 h) of preimplantation rabbit embryos to elevated temperatures (41.5 degrees C or 42.5 degrees C) in vitro on their developmental capacity. Fertilized eggs recovered from female oviducts at the pronuclear stage (19 hpc) were cultured at standard temperature (37.5 degrees C) until the morula stage (72 hpc). Afterwards, the embryos were divided into two groups, cultured for 6 h either at hyperthermic (41.5 degrees C or 42.5 degrees C) or standard temperature (control 37.5 degrees C), post-incubated overnight (16-20 h) at 37.5 degrees C and then evaluated for developmental stages, apoptosis (TUNEL), proliferation (cell number), actin cytoskeleton and presence of heat-shock proteins Hsp70. It was observed that hyperthermia at 41.5 degrees C did not alter progression of embryos to higher preimplantation stages (expanded and hatching/hatched blastocysts), rate of apoptosis, total cell number of blastocysts and structure of actin filament compared to 37.5 degrees C. Western-blotting revealed the presence of heat stress-induced 72 kDa fraction of Hsp70 proteins in granulosa cells (exposed to 41 degrees C) and embryos (exposed to 41.5 degrees C). Following the elevation of temperature to 42.5 degrees C embryo development was dramatically compromised. The embryos were arrested at the morula or early blastocyst stage, showed an increased rate of apoptosis and decreased total cell number compared to control. The structure of actin filaments in most of blastomeres was damaged and such blastomeres often contained apoptotic nuclei. In this group a presence of heat-stress-induced fraction of Hsp70 proteins had not been confirmed. This is the first report demonstrating a threshold of thermotolerance of rabbit preimplantation embryos to hyperthermic exposure in vitro. A detrimental effect of higher temperature on the embryo is probably associated with the loss of their ability to produce Hsp70 de novo, which leads to cytoskeleton alterations and enhanced apoptosis.

Survival and ultrastructure of gene-microinjected rabbit embryos after vitrification.

Morphological signs of injury and subsequent regeneration following vitrification of either rabbit gene microinjected (Gene-Mi) or intact in vitro cultured embryos derived from in vivo fertilized eggs were evaluated by post-warming recovery in culture and analysed by transmission electron microscopy (TEM). The percentages of vitrified/warmed Gene-Mi embryos that reached the blastocyst stage (69%) and hatched (57%) did not differ significantly from those of intact embryos (78% and 56%, respectively). In contrast, in vitro development of embryos to the blastocyst stage among non-vitrified intact (96%) and Gene-Mi (90%) embryos compared with both the intact vitrified (78%) and Gene-Mi vitrified (69%) groups, as well as hatching rate (94%, 90% vs 56%, 57%, respectively) varied significantly (p < 0.001). Observations by TEM showed that the vitrified/warmed intact or Gene-Mi embryos without post-culture displayed severe degenerative changes among their cells. During 24 h of culture a proportion of the embryos were able to regenerate and complete the compaction process. Nevertheless the signs of previous injury were retained, such as swollen cytoplasmic organelles and remaining cellular debris in the perivitelline space. These observations indicate that the procedure of gene Mi does not significantly compromise embryo tolerance to cryopreservation and post-warming developmental ability. Severe changes in embryo morphology, observed at the ultrastructural level, can be attributed to a direct influence of the vitrification process rather than to the Mi procedure itself.

Ultrastructural morphometry of precompacted bovine embryos produced in vivo and in vitro after activation by electric pulse AC/DC.

Early bovine precompacted embryos (at 1- to 8-blastomere stage) were analyzed by electron microscopy. The volume density of cellular components was determined by morphometric analysis to quantify the ultrastructure of early bovine embryos produced either in vivo or parthenogenetically after stimulation of oocytes by electric pulse AC/DC. In embryos obtained in vivo, most of cellular volume was occupied by cytoplasm (82.93%). The relative volume of lipids, vacuoles, mitochondria was relatively low (5.46; 5.07; 3.78%, respectively), and the relative volume of Golgi apparatus and cell inclusions was the lowest (1.51%). AC/DC-derived parthenogenotes had a relative high area occupied by vacuoles and lipids (18.68 vs. 14.33%) and a significantly lower relative volume was occupied by cytoplasm (60.63%) when compared with the control in vivo embryos. These observations demonstrated that parthenogenetic embryos had significantly altered ultrastructure, indicating extensive subcellular damages. These findings are discussed from the physiological and functional point of view.

Comparative morphometry of precompacted bovine embryos produced in vivo or in vitro after parthenogenetic activation and intracytoplasmic sperm injection (ICSI): ultrastructural analysis.

Early bovine precompacted embryos (1 to 8 blastomeres) were analysed by electron microscopy. The volume density of cellular components was determined by morphometric analysis to quantify the ultrastructure of early bovine embryos produced either in vivo or in vitro both after fertilisation by intracytoplasmic sperm injection (ICSI) or from electrically stimulated oocytes (AC/DC). In normal embryos obtained in vivo (control), most of the cellular volume was occupied by cytoplasm (82.93%). The relative volume of lipids, vacuoles, mitochondria, Golgi apparatus and inclusion bodies was minimal. In the group of embryos after parthenogenetic activation (AC/DC) a relatively high proportion of the volume was occupied by vacuoles and lipids (18.68% vs 14.33%). Early ICSI-derived embryos contained the lowest relative volume of cytoplasm (58.33%) compared with the control embryos (in vivo) and parthenogenetically AC/DC-activated embryos and a higher volume was occupied by lipids (13.25%) and vacuoles (12.92%). It is concluded that in vitro produced embryos have a significantly altered ultrastructure, indicating extensive cellular damage.

Autoradiographically detected impairment of RNA synthesis pattern in 8-16 cell bovine embryos after irradiation.

Early preimplantation bovine embryos at 8- or 16-cell stage were analysed by [5-3H]uridine autoradiography for distribution of newly synthesized RNA after 60Co irradiation with a single dose of 1 Gy, 2 Gy or 4 Gy gamma rays, respectively. Embryos irradiated with a single dose of 1 Gy showed equally decreased synthesis of RNA in nucleoplasma as well as in nucleolus. In embryos irradiated with a single dose of 2 Gy or 4 Gy, RNA synthesis was decreased and localized mostly on the periphery of the nucleus; in both cases of irradiation, the nucleus center being without labelling. In most of embryos irradiated with a dose of 4 Gy, the nucleoli were not labelled, and an increasing occurrence appeared of various nucleus chromatin segregation forms, mainly as its marginalization.

Bovine abnormal preimplantation embryos: analysis of segregated cells occurring in the subzonal space and/or blastocoele cavity for their nuclear morphology and persistence of RNA synthesis.

Bovine embryos in the early blastocyst/blastocyst stage were analysed by [5-3H]uridine labelling followed by electron microscopic autoradiography. In normal control embryos an intact zona pellucida, evenly developed blastomeres and a transparent perivitelline space were seen. In this group, the blastomeres of the trophoblast and embryoblast showed high homogeneous labelling localised in the nucleoplasm and even more intense labelling in the nucleolus. On the contrary, in addition to evident cytoplasmic disintegration, a clearly different labelling pattern and a low labelling intensity were observed in the nuclei of the segregated cells in the subzonal space and in those free in the blastocoele cavity. A typical nuclear morphological feature of these blastomeres was chromatin marginalisation, similar to that observed in embryos treated with actinomycin D for transcription inhibition. It is concluded that the segregated cells are arrested in their further differentiation.

Detection of genome impairment in bovine early embryos by autoradiography: a methodological note.

The applicability of Pavlok's method characterising the nuclear status of early preimplantation bovine embryos by nuclear labelling pattern after a short pulse of [5-3H]uridine (revealing in situ detection of RNA transcription at the onset of the major embryonic transcription) was tested on experimentally irradiated 8- to 16-cell bovine embryos. After [5-3H]uridine labelling the semi-thin sections of these embryos were analysed by autoradiography for intranuclear distribution of newly synthesised RNA expected to be influenced by increasing doses of irradiation by gamma rays from a 60Co source. In control embryos, the labelling was homogeneously distributed in nucleoplasm and in nucleoli. The expected effects were clearly detected already in embryos irradiated with a dose of 2 Gy, in which low-level RNA synthesis was localised mostly at the periphery of the nucleus, the nuclear centre being without labelling. A detailed analysis of consecutive sections of embryos from all groups of irradiated and control embryos, using an arbitrary scale considering these effects, confirmed the detectability of the threshold level of genome impairment.

[Characteristics of the cumulus-oocyte complex during the preovulatory period in superovulated heifers]. / Charakteristika cumulus-oocytárnych komplexov superovulovaných jalovíc v preovulacnom období.

The nature of cumulus--oocyte complexes was examined in PMSG (group 1, n = 18) and FSH (group 2, n = 30) stimulated heifers. Laparoscopy was performed 65 h after cloprostenol application. The number of follicles was 13.67 +/- 0.75 and 12.67 +/- 0.81 (P greater than 0.05) in group 1 and 2, respectively (Tab. I). The recovery rate of oocytes was 56% in the first and 67% in the second group (Tab. I). The cumulus oophorus was divided into three groups: compact, expanded and partial (Tab. II). Most oocytes (65 and 75% in the first and second group, respectively) exhibited an expanded cumulus (P greater than 0.05). In the first and second group 11 and 26% (P less than 0.01) of oocytes with the extruded first polar body were aspirated (Tab. III). As judged from the pool of visible follicles, the superovulation response to stimulatory treatment and recovery rate of oocytes in the present experiment were not different from the results published earlier. The degree of the cumulus oophorus expansion is an indicator for the evaluation of cumulus--oocyte complexes. After the preovulatory LH peak the disintegration of cumulus oophorus proceeds from glycosaminoglycan accumulation. In our experiment this effect resulted in a significantly higher number of oocytes with expanded cumulus in both treatments. The enlargement of perivitelline space is related to a subsequent release of the first polar body in the preovulatory period. It can be seen from our results that after FSH treatment it is possible to reach the high number of oocytes with the extruded polar body.(ABSTRACT TRUNCATED AT 250 WORDS)