This study was carried out to identify the possible effects of epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on cumulus expansion and nuclear maturation in bovine oocytes matured in vitro in serum-free media. Bovine follicular oocytes were matured in vitro and were then classified as cumulus cell-enclosed oocytes or denuded oocytes. They were then cultured for 24 h in TCM-199 (tissue culture medium-199) with EGF (50 ng ml-1), IGF-I (100 ng ml-1) and EGF plus IGF-I (50 and 100 ng ml-1, respectively). At the end of the culture period, the morphology of oocytes was evaluated for cumulus expansion and nuclear stage of maturation. In Expt 1, percentages of oocytes reaching maximum cumulus expansion were: 12.5% (control), 46.5% (EGF), 15.2% (IGF-I) and 52.8% (EGF plus IGF-I). In Expt 2, the respective rates of nuclear maturation were: 35.6%, 52.1%, 45.5% and 61.4% for cumulus cell-enclosed oocytes, and 35.3%, 46.6%, 45.4% and 42.5% for denuded oocytes; the same growth factor treatments were used in both cases. There was no significant effect of IGF-I on cumulus expansion. Maximum rates of cumulus expansion and nuclear maturation were obtained in the presence of both growth factors. These results lead to the following conclusions: (i) EGF, either alone or together with IGF-I, stimulates cumulus expansion; and (ii) both growth factors, acting alone or together, enhance nuclear maturation in oocytes surrounded by compact cumulus cells.

The effects of different combinations of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on cumulus expansion and meiotic maturation were examined in rabbit oocytes. Selected rabbit follicular oocytes were matured in vitro and were classified as cumulus-oocyte complexes or denuded oocytes. They were cultured in TCM 199, and were treated with growth factors at different concentrations: EGF at 0, 1, 10, 50 and 100 ng ml-1, IGF-I at 0, 50, 100 and 200 ng ml-1 and EGF plus IGF-I at 10 + 50; 10 + 100; 50 + 50 and 50 + 100 ng ml-1, respectively. After 6 h of culture, the oocytes were assessed for nuclear maturation and after 16 h of culture, for cumulus expansion and maturation stage. After culture for 6 h, the incidence of germinal vesicle breakdown was higher (P < 0.05) in all of the growth factor treatments tested compared with controls. After culture for 16 h, EGF enhanced the incidence of cumulus expansion at all of the concentrations tested. Cumulus expansion was greatest with 50 mg EGF ml-1 plus 100 ng IGF-I ml-1 (72.0% versus 2.4% in controls). Treatment with IGF-I significantly increased (P < 0.05) the incidence of metaphase II stage, and maximum stimulation occurred at 100 ng IGF-I ml-1 (84.5% versus 31.1% in controls). However, IGF-I did not affect cumulus expansion. When denuded oocytes were used, no positive effects on nuclear maturation rates were observed for any treatment. These results suggest that: (1) EGF, either alone or with IGF-I, stimulates cumulus expansion; (2) the addition of IGF-I or EGF plus IGF-I significantly enhances nuclear maturation in immature rabbit oocytes; and (3) this effect is mediated by the presence of cumulus cells.

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Monitoring ovarian cycles through hormonal analysis is important in order to improve breeding management of captive elephants, and non-invasive collection techniques are particularly interesting for this purpose. However, there are some practical difficulties in collecting proper samples, and easier and more practical methods may be an advantage for some institutions and/or some animals. This study describes the development and validation of an enzymeimmunoassay (EIA) for progestins in salivary samples of African elephants, Loxodonta africana. Weekly urinary and salivary samples from five non-pregnant elephant cows aged 7-12 years were obtained for 28 weeks and analyzed using EIA. Both techniques correlated positively (r = 0.799; P < 0.001), and the cycle characteristics obtained were identical. The results clearly show that ovarian cycles can be monitored by measuring progestins from salivary samples in the African elephant. This is a simple and non-invasive method that may be a practical alternative to other sampling methods used in the species.