Parthenogenesis and activation of mammalian oocytes for <i>in vitro</i> embryo production: A review

Abstract

Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occurs without fertilization by a male. Parthenogenesis occurs naturally in aphids, Daphnia, rotifers, nematodes and some other invertebrates but can also be induced efficiently in mammalian oocytes by providing appropriate stimuli in-vitro. Recently, parthenogenesis has attracted wide attention because of the role of activated oocytes in the field of research that have been described such as intra cytoplasmic sperm injection, cloning by nuclear transfer, somatic cell cloning, investigating culture conditions etc. & potential for deriving pluripotent stem cell lines and their differentiation into various cell lines that can be utilized for various tissue engineering applications. The parthenogenetically activated oocytes possess maternal genome and can developed in to either haploid, diploid or polyploidy embryos with the help of it we can analyze the possible role of all the genes involved in imprinting processes as well as the role the paternal genome plays during early embryo development by comparing them with fertilized embryos. Several methods are able to induce parthenogenetic activation through the elevation of cytoplasmic free calcium in oocytes. But one common, universal method or activation agents has not been developed for all species because the process is highly specific for each species. Therefore, activation step for each species need to be optimized accordingly. This review describes the general method of activation of mammalian oocytes and their genomic imprinting analysis.

Pronuclear formation by ICSI using chemically activated ovine oocytes and zona pellucida bound sperm

“…Oocyte activation implies an increase of intracellular free calcium, causing the degradation of the maturation promoting factor (MPF), which is essential for the resumption of the second meiotic division and the formation of both PN [25, 35]. …”

“…ETL is among the most utilized chemical activators through the formation of inositol 1,4,5-triphosphate and its union to the membrane receptors in the endoplasmic reticulum releasing of intracellular calcium [25, 36, 37]. Other chemical activators include CAI and ION, which induce the liberation of intracellular calcium stored in the endoplasmic reticulum, evident by the activation of several proteolytic pathways calcium dependent that drive the destruction of cyclin B, reducing the activity of MPF [25, 36, 38].…”

“…Other chemical activators include CAI and ION, which induce the liberation of intracellular calcium stored in the endoplasmic reticulum, evident by the activation of several proteolytic pathways calcium dependent that drive the destruction of cyclin B, reducing the activity of MPF [25, 36, 38]. …”

“…This condition is essential for the normal development of the embryos [23]. When oocytes are artificially activated, a high probability that the resultant blastocysts will be parthenogenic exists [17, 24, 25]. Therefore, the objective of the present study was to determine the efficiency of fertilization using ICSI with chemically activated ovine oocytes with sperm selected by swim-up (SU) or SU plus binding to ZP (SU + ZP).…”

"Aktivasi dan Tingkat Perkembangan Embrio Partenogenetik Mencit Setelah Dipapar Calcimycin dan Ionomicyn (ACTIVATION AND DEVELOPMENT RATE OF MICE PARTHENOGENETIC EMBRYOS EXPOSURED IN CALCIMYCIN AND IONOMICYN)"

“…Pada mamalia, sel telur merupakan satusatunya sel yang secara alami memiliki kemampuan untuk menghasilkan individu baru melalui perkembangan embrio di dalam uterus. Walaupun demikian, sel telur yang telah mencapai tingkat kematangan yang sempurna akan memasuki masa istirahat ketika berada pada tahap metaphase II (Kharche et al, 2013). Berkembang atau tidaknya sel telur menjadi embrio tergantung pada keberadaan stimulan yang berasal dari spermatozoa melalui proses fertilisasi di dalam ampula tuba Fallopii.…”