58 embryos at 1, 2, 3 and 4 cell and morula stage were recovered from the oviduct and the uterine horn of the Ha-bai, Du-ha and Du-chang-ha pigs, 24 hours, 2 or 3 days of pregnancy, and were observed with SEM and TEM. The zona pellucida of 1 cell embryo was removed by treatment with 2.5％ pronase for visualization of the cell surface structure.The findings are as follows:1. The surface of the 1 cell stage embryo was densely populated with microvilli and sperm can be found on the surface with its head and tail surrounded by the microvilli and its plasma membrane of the equatorial segment of acrosome intact.2. Many spermatozoa were observed both on the surface and inside the zona pellucida of the 2 celled embryo.3. By the 4 cell stage, some of the spermatozoa had penetrated through the zona and got into the perivitelline space. 4. There were still some spermatozoa on the zona surface of the morula.5. The TEM observation revealed that the heads of supernumerary sperm were located within the cytoplasm of the blastomeres of the embryos from 1 to 4 cell stages and still not decondensed. Some of these sperm heads were actually found within the phagocytic vacuoles of the 4 celled embryos. The ultrastructure of these polyspermic embryos was normal.These results showed that polyspermy in the pig did not intefere with the cleavage of the embryo and the embryo possessed the ability to dispose the excessive sperms.

On 10 days of pregnancy the blastocysts of 3 mm and 9 mm in diameters wereflushed out from the uterine horns of the Du-Chang-Ha and Dong-Bei-Min pigs.The blastocysts were divided into four parts,that is the embryonic disc,the animalpole,the lateral part and the vegetal pole.The outer and inner surface of the fourparts were observed with SEM and the findings are as follows:1,The 3 mm blastocystsThe outer surface of the embryonic disc was still covered with trophoblasticcells.Three kinds of cells can be discerned:the cell with round prominences andlong microvilli(MV);the cell with thin and long MV,the cell with smooth sur-face.The trophoblast cells in other areas of the blastocyst were similar but slightlyflat.The inner surface of the blactocyst consists of endoderm cells which weredifferent in the four parts.From the embryonic disc to the vegetal pole,the surfacestructure of the endoderm cells changed regularly from small to large from dome-shaped to flat and the distance between nuclei increased gradually.The MVs on thecell surface:became less.These findings suggested that endoderm cells weremoving from the center of the embryonic disc to the vegetal pole.There weremany holes on the marginal area of the cells.The edge of the cell on the innersurface of the vegetal pole forms a network.Many round granules can be seen inthe holes of the network.Their function may be for the transport of nutrients.2,The 9 mm blastocystsThe outer surface of the embryonic disc was not covered with trophobla-stic cells but covered with ectoderm cells.The ectoderm cells in the primitivestreak had long MV on their surface but short ones on other areas of the disc.The inner surface of the embryonic disc was endoderm cells.The MVs on theendoderm cells was much more numerous than the MVs on the ectoderm cells.Thedifferentiation of the cells in the pig blastocyst was also discussed.

Transposition of simple or composite forearm island flaps with a radial vascular pedicle was performed in repairing tissue defects of the hand and reconstruction of the thumb in 16 patients. It was found to be easy to operate and no suturing of blood vessels was necessary. The postoperative swelling was less marked. The flap was good in texture and sensation after the operation. The overall result wassatisfactory. Anatomic-physiological situdy was also carried out. 16 patients have been operated on, including 2 thumb reconstructions, with satisfactoryresults.