Fetal Ocytes: a potential resource in embryo transfer? progress and prospects
Assy, R.J|Balema, O.B|Kessy, B.M|Mutayoba, B.M / 2000

he technique of in vitro oocyte maturation, fertilization and embryo transfer (IVMF-ET), which was started about 25 years ago is now an integral part of dairy cattle breeding in some countries. However, its extensive application is amongst other reasons, being hindered by the small number of follicles from which the oocytes are obtained. In fetal ovaries, there is a large population of primordial follicles and which could form an alternative source of oocytes for IVMF-ET. Utilization of fetal oocytes would eliminate the necessity for adult animals in passing from one generation to the next, and thus, shorten to a big extent, the generation interval. In vivo, an interaction between follicular and body reproductive hormonal levels, and oocyte morphology, is critically important for the control of oocyte maturation and development competence.To understand and evaluate the potential use of bovine fetal oocytes in IVMF-ET, studies are being conducted to evaluate the onset and progress of Follicle Stimulating Hormone (FSH), estradiol 17b (E2) and progesterone (P4) hormones secretion, meiosis onset and progression, and morphology of fetal follicles and oocytes. Preliminary gross morphological findings from 73 fetuses indicate that 32% of those that were >150 days old (or about 11% of the total) had vesicular follicles. There is immunohestochemical evidence that FSH secretion starts during the fetal period and in addition, with advancing age, there was follicular and oocyte growth, and progression in meiotic maturation.