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.