Analysis of polarity of mammalian embryos

• Project/Area Number: 06660389
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Basic veterinary science/Basic zootechnical science
• Research Institution: Rakuno Gakuen University
• Principal Investigator: KOYAMA Hisaichi Rakuno Gakuen University, Dept.of Dairy Science Associate Professor, 酪農学部, 助教授 (10094822)
• Co-Investigator(Kenkyū-buntansha): SUZUKI Hiroyuki Hirosaki University, Dept.of Agriculture Associate Professor, 農学部, 助教授 (50211313)
• Project Period (FY): 1994 – 1995
• Project Status: Completed (Fiscal Year 1995)
• Budget Amount: ¥2,000,000 (Direct Cost: ¥2,000,000); Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
• Keywords: Mammalian embryo / Polarity / Nuclear totipotency / Nuclear transfer

Research Abstract

Introduction The objectives of the current study were 1) when surface polarization of blastomeres first appears during cleavage of the cattle, rabbit and hamster embryo using FITC-labeled Concanavalin A ; 2) Wheter the polarization of the cytoplasm of blastomeres appears like as surface by scanning electron microscopy and ; 3) to investigate the relationship between polarity and nuclear totipotency of early cells by unclear transfer experiments of polar and non-polar blastomeres.
Result and Discussion Cow Blastomeres : The polarized cells had a single pole of fluorescent. The non-polarized cells showed a ring stain. The first significant incidence of blastomeres displaying clearly polarized staining pattern was seen at the 10-to 66-cell stage. The percentage of blastomeres that were polar varied from 25% to 88%, for an average of 51.4%. Rabbit Blastomeres : It was possible to conclude that none of the blastomeres from 8-to 32-cell embryos were polarized with respect to their binding of FITC-Con A.The percentage of blastomeres from 32-to 66-cell embryos that were polar varied from 25% to 88%, for an average of 51.4%. Hamster Blastomeres : The distributions of microvilli over the surface of blastomeres were compared by SEM.The 8-to 66-cell embryos had two different cell types : 1) cells that were uniform population of microvilli over the entire cell surface and, 2) cells with a single pole of microvilli. Developmental potential of polarized bovine blastomeres : Bovine embryos at the 34-cell stage were separated into individual blastomeres and labelled with FITC-Con A for nuclear transfer. After nuclear transfer, none of the polarized and non-polarized blastomeres developed to the 2-cell stages. Polarization of organella of bovine embryos : Rabbit embryos at 32-cell stage were observed with SEM.Nucleus of the majority of the outer blastomeres became located close to the outer surface of the cells facing the milieu. This observation contrasts to the inner blastomeres where the nucleus was always restricted to the center of the cells. Conclusions : Observations by FITC-Con A staining or scanning electron microscopy on the dissociated cells confirmed the cellular polarization of the cow, rabbit and hamster embryos. According to this result, FITC-Con A staining allowed us to separate polarized cells from non-polarized cells. Further tests on nuclear transfer are needed to confirm the adequacy of this staining system.