The study is subdivided into two different parts: the first part deals with the development of a method to gain uterus milk in vivo during the preimplantation periode in cattle for the investigation of regulatory factors. The second part investigates different proteases in bovine follicles 20 hours after GnRH (Gonadotropin releasing hormone) injection (shortly bevor ovulation) for comparable as well as in the corpus luteum (CL) during oestrous cycle and induced luteolysis. In addition apoptotic as well as anti-apoptotic factors were evaluated in the CL during oestrous cycle and induced luteolysis.

For the development of a method for gaining uterus milk in vivo during the first 24 days of gravidity in cattle, nine heifers were cycle synchronised using the Ovsynch method and artificially inseminated. Before flushing an epiduralanaesthesia was given and both uterus horns were flushed with 13ml 0.9% NaCl using a balloon embryo transfer catheter at day 5, 7, 12, 17 and 24 of gravidity. The catheter was placed 1cm cranial to the bifurcatio uteri in both horns. It was possible to retrive between 3ml and 13ml of the used flushing fluid. The uterus milk from the ipsilateral horn was inspected for an embryo and an EDTA-stabilisator was given to the uterus milk of both horns. An infection of the uterus occured in three heifers after the second and in five heifers after the third flushing. In one heifer no infection was found. Between day 17 and day 24 all heifers showed clear signs of oestrus. It was possible to detect progesterone, oestradiol-17-beta, PGF2alpha and VEGF via enzyme immunoassay (EIA) and radio immunoassay (RIA), respectively. Because of the occurred infection no statistic analysis was made. But it could be seen that the level of progesterone ranged between <0.1 and 0.4ng/ml, whereas no correlation to the inflammation was found. The values of the native uterus milk should be about 10-fold higher, because of the diluting effect of the flushing fluid. The pattern of oestradiol-17-beta was erratic, because the oestradiol levels of the flushing fluid from heifers with no infection till day 12 of gravidity could not be related to each other. It could be shown in further tests that high oestradiol-17-beta levels were measured via EIA in 0.9% NaCl with EDTA-stabilisator compared to 0.9% NaCl without the stabilisator. VEGF revealed levels between 0.08 and 2.58ng/ml, whereas the higher levels were seen during inflammation. The level of PGF2alpha showed a clear correlation to the infection. But there were also differences seen between the different heifers or even between the two uterus horns of one animal during the first flushing, which might be due to the massage of the uterus horns while flushing, which can induce prostaglandin secretion. The method of gaining uterus milk in vivo should be changed as follows: to prevent an endometritis just one flushing should be done per gravidity with gaining of the embryo, so that the heifer can be inseminated again after two oestrous cycle. Again both horns should be flushed, whereas one sterile disposable catheter should be used for each horn and the flushing should be devided into two parts: first flushing with 13ml of sterile 0.9% NaCL for biomolecular methodes, then flushing of the embryo using 5 x 50ml sterile PBS buffer. The embryo should be frozen in RNA-Later at -80° for further investigations. The received flushing fluid should be separated in two aliquotes, whereas one is used for the oestradiol-17-beta measurement and must not contain the EDTA-stabilisator. These two aliquotes should be centrifugated and the fluid should be stored seperatly at –20° from the received cell pellet. Part of the cell pellet can be used for the identification of the cells found in the uterus lumen and the rest stored in RNA-Later at –80° for further biomolecular investigations. For the evaluation of prostaglandins in the uterus milk it should be considered to treat the heifers with a prostaglandin synth