Endometrial tissue was collected from cows to determine effects of day of the estrous cycle, location of the ovulatory structure and progesterone (P₄) on endometrial protein secretion. Day 0 (estrus) endometrial tissue released more protein than tissue collected on d 9, 14 or 18. Protein synthesis was greater on d 0 and 18 than d 9 and 14. Endometrium from the uterine horn contralateral to the ovulatory structure synthesized more protein than endometrium ipsilateral to the ovulatory structure. Seventeen protein bands were identified by electrophoresis. Proximity of the ovulatory structure to the uterine horn affected the presence of four proteins. Quantitative release of seven proteins was influenced by day of the estrous cycle and uterine horn. Day of the estrous cycle and location of the ovulatory structure alter endometrial protein secretion and synthetic activity and have effects on individual proteins. A second project utilized 116 gilts and sows to evaluate estrous synchronization/superovulation schemes. Pronuclear microinjection and zygote culture in excised mouse oviducts also was assessed. Synchronization/superovulation procedures were: 1) sows observed for estrous behavior (NAT), 2) cyclic gilts synchronized with altrenogest (ALT) for 15 to 19 d and superovulated with pregnant mares serum gonadotropin (PMSG) and human chronic gonadotropin (hCG; LALT), 3) gilts between 11 and 16 d of the estrous cycle receiving ALT for 5 to 9 d and superovulated (SALT), and 4) precocious ovulation induced with PMSG and hCG (PRE). Zygotes from PRE donors received microinjection of buffer, DNA or no microinjection. Ova were cultured in modified Krebs Ringer Bicarbonate medium (KRB) or mouse oviduct (MO) explants. SALT and PRE had higher ovulation rates than LALT (24.7 ± 2.9, 24.3 ± 1.8 vs 11.6 ± 2.7; x̄ ±SEM). DNA microinjection resulted in a lower (P<.05) cleavage index (CI) than buffer injection or no microinjection (2.16 ± .10 vs 2.80 ± .13 and 2.93 ± .10). MO improved (P<.01) CI over KRB. MO culture for 72 h was the most beneficial system (P<.05; CI 3.25 ± .12). Cl of 2.66 ± .18, 2.79 ± .14 and 2.40 ± .14 were observed from MO for 48, 96 and 120 h, respectively. Transfer of 505 DNA microinjected zygotes into 17 recipients produced seven litters and 50 piglets of which eight were transgenic. Microinjection of DNA, not merely the mechanical procedure, was detrimental to embryo development and culture for 72 h in MO provided optimal CI. / Ph. D.