Advances in Embryonic and Placental Development Abstract:
Early embryonic development needs detailed investigations if we have to reduce embryonic mortality. Embryonic mortality details have been reviewed (wani, 2005). The reproductive abnormalities have been discussed and a sequential photographic presentation of embryonic mortality have recently been published (Khatoon et al 2007). The critical period when maximum embryonic losses go unnoticed is the period before attachment. Losses before actual union of foeto-maternal tissues can be missed and calculations of embryonic mortality estimates remain unaccounted for. Some recent studies of (Wani 2006, Khatoon et al 2006) have paved a new innovative model for investigation on foeto-maternal development and its attachment. This paper describes the detailed embryonic development, blastocyst elongation, formation of cotyledons within elongated blastocyst, their ramifications and networking of vasculature and formation of foetal placental unit.
Second and 3rd generation animal biotechnologies as reviewed (Wani, 2005) are multiple ovulation, embryo-transfer, preservation, cloning, micromanipulation splitting of embryos and nuclear transfer. The 4th Generation reproductive technologies have advance beyond our imagination and now we do have transgenic goats giving milk rich in insulin.
The application of this advancement for diagnostic, therapeutic and economic uses especially its transfer to human medicine or for field application in animal industry needs further research and evaluation.
The another fact which can be of importance is the number of cells per embryos. During first day these may be two cells but after 8 days the cell number increases to 120 or more. It takes 32 hours for the oocyst after fertilization to reach the two cell embryo. Another 13 hours are needed to develop it into a four cell embryo.