Survival of mouse embryos after vitrification depending on the cooling rate of the cryoprotectant solution.

The aim of the study was to determine the relationship between the rate of cooling of eight-cell mouse embryos to the temperature of liquid nitrogen (-196 degrees C) and their developmental capacity after thawing on the basis of their ability to leave the zona pellucida ('hatching') during in vitro culturing. Eight-cell embryos were obtained from superovulated female mice and divided into three experimental and one control group. Embryos from the experimental groups were cryopreserved by the vitrification method using ethylene glycol as cryoprotectant.

[Thyroid and ovarian hormones in ewes treated with gestagens and PMSG in the spring season].

Recent experimental observations have shown that the thyroid gland plays a dominant part in the induction and maintenance of anoestrus in ewes. The mechanisms of the anoestrous effects of the thyroid gland are still unclear. On the basis of experiments, in which after thyroidectomy at the onset of sexual activity LH production was maintained also during the spring months, iodothyronines have been supposed to stimulate the inhibitory effects of oestrogens upon the neuroendocrine centres that generate pulsatile LH secretion (Moenter et al.

Accumulation of trace elements in sheep and the effects upon qualitative and quantitative ovarian changes.

The distribution of Cu, Zn, Fe, Mo, Se, As, Cd and Pb was determined in the organs of sheep that died of Cu intoxication from a Cu plants emissions. Simultaneously, quantitative and qualitative changes in the ovaries were evaluated. In sheep that died of copper intoxication, the highest Cu levels were in the liver (1797 +/- 946.

[Dynamic changes in hematologic parameters in the blood of sheep during estrus synchronization and in the subsequent early pregnancy].

Observation of hematological indices which are a reflection of physiological processes in the individual phases of the reproductive cycle, presents one of the methods of controlling the homeostasis of the ewe's organism. This work focused on the observation of selected indices during synchronization treatment and in the first days of pregnancy The experiment included 10 conventionally bred animals. Blood was obtained from the v.

[Levels of sodium and potassium and their relation to ovarian hormones during estrus synchronization and pregnancy in ewes].

The active transport of mineral substances by cell membranes plays an important role in the neurohumoral regulation of reproductive processes in farm animals. A great importance is attributed to lipoproteins as sources of the primary precursor of steroid synthesis in the placenta and ovaries (Knopp et al., 1986; Grummer et al.

Growth and development of follicles in different phases of the oestrous cycle in cows in relation to the presence of the corpus luteum and an oestrogen-dominant follicle.

In this work recruition and growth of follicles and quality of the largest ones were determined and compared in the individual stages of the bovine oestrous cycle (stages I, II, III and IV - days 1-4, 5-10, 11-17 and 18-21, respectively) in relation to the presence of the corpus luteum and an oestrogen-dominant follicle on the ovary. The maximum proportions of small (< 4.9 mm), medium-sized (5.

[Alkaline phosphatase during the puerperium in ewes and its relation to thyroid hormones and ovarian steroids].

Triacylglycerols as the sources of cholesterol, the primary precursor of steroid synthesis, are one of the factors that limit the speed of steroidogenesis. Synthesis and resynthesis of triacylglycerols depend, in addition to other factors, on phosphatid hydrolysis that is controlled during pregnancy by placentary ALP (Sumikawa et al., 1987) and the FFA pool in the systemic blood stream.

[Levels of total lipids, cholesterol and progesterone during estrus synchronization and pregnancy in sheep].

Our investigations were concerned with dynamic changes in total lipids (CL), cholesterol (CHOL) and progesterone (P4) in blood serum of sheep in the period of oestrus synchronization treatment and during mating and gravidity. Our experiment was carried out using 10 animals housed under the conditions of productive rearing. Blood samples were taken from v.

[Dynamics of changes in the cytological picture of vaginal smears and circulating ovarian hormones during the puerperal period in ewes].

A postparturient period is characterized by low basal secretion of adenohypophysis gonadotropins with the following appropriate changes in ovarian hormones and their response to the morphology of vaginal epithelium. In this study the dynamics of the cytological picture of vaginal swabs and ovarian hormones 17 beta-oestradiol (E2) and progesterone was investigated in the puerpery of ewes. The objective was to obtain and extend the knowledge of cytological changes in vaginal epithelium and levels of ovarian hormones of ewes after parturition and of their relationships from the first several days after lambing until the 51st day of the period of observation.

[The effect of repeated administration of carbetocin (Depotocin, Spofa) in the first days postpartum on levels of thyroxine, triiodothyronine, 17 beta-estradiol, progesterone and on fertilization].

Application of new procedures in the sphere of the control of sexual functions requires an extension of present knowledge of postparturient endocrinium or endogenic factors comprised in postparturient physiology of sexual activity. According to recent data, oxytocin, besides its uterotonic and luteolytic activity, acts as an ovarian factor in the local intrafollicular regulation of stereidogenesis and as a modulator of uterine secretion of prostaglandines. Based on present knowledge of oxytocin effects, this study was aimed at investigation of the influence of repeated carbetocin (Depotocin inj.

[Nuclear volume of cells in the stratum granulosum and theca folliculi interna of the largest dominant and atretic tertiary follicles in sheep during the selection process].

According to available literary data, an increased nuclear volume of endocrine gland cells, various structures of the diencephalon and endocrine ovarial structures could be observed when the respective organs and structures were more active; a decreased nuclear volume was revealed when the activity of the respective organ or its structure was suppressed (Mess, 1962; Maracek and Arendarcik, 1976, 1978). Attention was paid to the karyometric analysis of follicular cells of the stratum granulosum (SG) and secretory cells of the theca folliculi interna (TFI) during selection of the dominant ovulatory follicle (DOF). The aim of this study was to determine differences in hte nuclear volumes of the granulosa follicular cells and the secretory cells of the inner theca of the DO1F in comparison with the largest atretic follicles (AF) as well as to verify the use of karyometric variance analysis for the evaluation of the selection process of the dominant ovulatory tertiary follicle.

[Dynamics of changes in the serum levels of cholesterol, thyroid and ovarian hormones in the postpartum period in ewes].

Postparturient anoestry, spontaneously changing over to seasonal anoestry, represents an important reserve of full utilization of the reproductive potential of sheep. In spite of the fact that the length of gestation in sheep only amounts to 148 days (+/- 5 days), inability of most sheep to enter the cycle during the spring season acts as a factor limiting the number of lambings--and at the same time production of lambs--to one lambing per year. In order to obtain more detailed knowledge of hormonal conditions in sheep puerpery, the presented work was directed at the study of dynamic changes in concentrations of thyroxine (T4), triiodothyronine (T3), 17 beta-estradiol (E2), progesterone (P4) and cholesterol (Chol) in the blood serum of ewes and at their mutual correlative dependences between the 36th hour and the 51st postparturient day.

[Biometric parameters of the uterus and ovaries in sheep after administration of Depotocin inj. Spofa in early puerperium].

Objectivisation of the physiological course of puerpery and control of involution processes of uterus represent topical questions of an increased frequency of lambing. Our study was directed at the determination of the weight, length of body and horns of uterus as well as of the weight, length, width and height of ovaries, following the administration of carbetocin (Depotocin inj. Spofa), in the puerperal period of Slovak Merino sheep.

[The effect of synchronization on estrus and pregnancy in sheep and on levels of thyroxine, triiodothyronine, 17 beta-estradiol, progesterone and cholesterol].

Knowledge of pathogenesis of sexual dysfunctions at altered thyroid activity is limited by the knowledge of multiple and ubiquitous action of its hormones throughout the organism. One of the possibilities of modulatory influence of thyroid hormones on sexual functions can be realized through the participation of thyroxine and triiodothyronine in the synthesis and metabolism of primary substrate of steroid synthesis--cholesterol. The presented work is aimed at the study of simultaneous dynamic changes of concentrations of thyroxine (T4), triiodothyronine (T3), 17 beta-estradiol (E2), progesterone (P4) and cholesterol (Chol) during synchronization of the rutting period and gravidity at parallel correlative evaluation of mutual relations of the followed parameters in ten Merino sheep in the seasonal period.

[Biometric parameters of the uterus, ovaries and levels of 17 beta-estradiol (E2) after delivery in sheep].

Biometric changes of uterus, ovaries, follicles and 17 beta-oestradiol (E2) concentrations were investigated in 15 lambing ewes of the Slovak Merino breed in the puerperal period. The sex organs were excised immediately after bleeding from ewes slaughtered on days 1, 7, 17, 25 and 34 post partum (p. p.

[The effect of steroidal dominance on cAMP, cGMP, progesterone and 17 beta-estradiol levels in the fluid of the largest follicle].

Concentrations and mutual correlations of the cyclic adenosin monophosphate (cAMP), quanosin monophosphate (cGMP), progesterone (P4) and 17-beta-estradiol (E2) were studied in the fluid of the largest follicles in cows, in dependence on the steroid dominance: estrogen-dominant (ED), progesterone-dominant (PD) follicles. Mean cAMP and cGMP concentrations in the follicular fluid in the estrogen-dominant follicles were significantly higher than in the progesterone-dominant follicles; in both cases at P less than 0.01.

[Changes in blood levels of progesterone, triiodothyronine and thyroxine and the results of quantitative histological analysis of the placentoma and corpus luteum in cows after prolonged labor].

Changes in the cell structure of the placentoma and the corpus luteum were subjected to quantitative histological investigation, parallel with the examination of the concentrations of progesterone (P4), triiodotyronine (T3) and tyroxin (T4) during parturition (Oth hour) and two and six hours after parturition. The hormone concentrations were determined by the RIA method. The results of the quantitative histological analysis of the placentomae and the corpus luteum suggest that when the placenta is retained there is a significantly higher number of maintained epithelial cells in the placentoma crypts and a higher number of unchanged small, dark and large, light lutein serraetion cells in the biopsy of the corpus luteum during the period under investigation.

[Serum levels of progesterone and estradiol in relation to tertiary follicles in the sheep ovary in proestrus and after administration of gonadoliberin].

Changes in progesterone (P4) and 17 beta-estradiol (E2) concentrations in blood serum as well as changes in counts and quality of tertiary follicles on ovary surfaces of ewes were investigated after administration of different GnRH doses on the 15th and 16th day of the oestral cycle. Progesterone (P4) and 17 beta-estradiol (E2) were determined by radioimmunological assays using RIA-test-Prog and RIA-test-Estra kits. It follows from the results that GnRH in Dirigestran inj.

[Changes in surface follicles and ovarian weight in testing for responsiveness in dairy cows after induction of superovulation using PMSG and cloprostenol].

We evaluated the ovaries of 34 cows cross-bred of the Slovak Pied and Lowland Black-pied breeds which were culled and intended for slaughter during the winter type of feed rations. For superovulation treatment we used PMSG in the preparation Serum Gonadotropin (Bioveta, Nat. Ent.

[Levels of thyroxine, beta carotene and vitamin A during successful and unsuccessful insemination of heifers].

We studied the concentrations of thyroxine (T4), beta-carotene and vitamin A (vit. A) on the day (zero-th day) of the first successful and unsuccessful insemination of 63 heifers that were administered feed rations balanced according to the Czechoslovak standard CSN 46,7070, housed all the year round, inseminated at uniform time (8:00-9:00 a. m.

[Correlation between the thyroxine, 17-beta-estradiol and luteinizing hormones in the systemic circulation and the rectal and vaginal temperature in heifers and cows after administration of cloprostenol].

Changes in the concentration of 17beta-oestradiol (E2) and luteinizing hormone (LH) and in the rectal and vaginal temperatures (RT and VT) were studied along with the changes in thyroxine concentration (T4) in three cows and three heifers in the luteal stage of the cycle; the animals had been intramuscularly treated with 2 ml Oestrophan (cloprostenol). The closeness of the correlation between T4 and the remaining parameters under study was determined by the calculation of the correlation coefficient and statistical significance. The concentrations of T4 before and during cloprostenol administration were high in comparison with the post-treatment levels.

[Biometric parameters of ovaries in the Tsigai strain of sheep and their changes after administration of cloprostenol].

The weight, length, width and volume of ovaries were determined as well as the number of follicles visible on the surface in relation to the presence of corpus luteum on the ovary in autumn period after Cloprostenol application. The ovaries of 43 sheep of the Tsigai breed were examined at the age of 2--4 years. The animals were divided into five groups.

[The effect of age, weight and the breed of heifer on the concentration of thyroxine during insemination].

We determined the thyroxine (T4) concentration in 63 heifers on 0th (day of insemination), 6th and 21st day after first and in repeat-breeder cows after second and third insemination in relation with the breed, age and weight of animals. The examination was carried out with a feed ration balanced according to the Czechoslovak State Standard CSN 46 7070, with all-the-year-round housing, with keeping the uniform time of insemination (8.00--9.

[Micromorphology of the endometrium of dairy cows after estrus synchronization with cloprostenol].

Trials were conducted to study and describe the micromorphological parameters of endometrium in five cows of the Black-Pied breed after the expiration of the synchronizing effect of cloprostenol in the Oestrophan inj. Spofa preparation. Two animals four to five days after oestrus were used as control and three cows on the sixth day of sexual cycle with rectally palpated corpora lutea were treated intramuscularly with 0.

[Cervical mucus in the heifer uterus during heat and insemination after feeding with synthetic beta-carotene].

The effect of beta-carotene was studied, as exerted on the amount, ductility, pH value, arborization and sperm survival time in the medium of the cervical mucus of heifers included in the breeding stock. The measurements were taken during oestrus and mating. The animals were divided into four groups.