The ultrastructure of delayed implanting mouse blastocysts during the period of Days 10 through 30 showed no differences throughout the period, but was different in the following points, as compared with that of intact blastocysts on Day 4.
I. Trophoblastic cells.(1) Elongation of trophoblastic cells that had long cytoplasmic projections at the intercellular portion near the blastocoele, (2) Appearance of the basement membrane-like material along the inner surface of the trophoblast, (3) Irregularity in the shape of the nucleus with invaginations of the nuclear membrane, and the thickening in the density of the nuclear substrate, (4) Disappearance of vacuolated cristae in mitochondria, (5) Decrease in the number of rough-surfaced endopl asmi c reticula, of polysomes and of Golgi apparatus, (6) Increase in the number of lipid droplets, (7) Disappearance of fibrous inclusions.
II. Inner cells.(1) Irregularity in the shape of inner cells with fine cytoplasmic projections, (2) Phenomena concerning nuclear and cytoplasmic organelles and fibrous inclusions similar to those in trophoblastic cells.

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To study fibrinolytic activity of preimplantation embryos, microassay methods to quantify plasmiogen activator in a single embryo were developed. 1. Preimplantation mouse embryos of day 2 and day 3 (4 cell to unhatched blastocyst stage) were incubated in 2μl medium drops containing 0.1% fibrin and 2 cu/ml plasminogen for 24 hours. Day 2 and day 3 embryos gave complete liquefaction of the fibrin drops. The amount of plasmin produced by a single ovum was assayed with synthetic fluorogenic substrate, Boc-Glu-Lys-Lys-MCA, and was 0.215±0.041 mcu with day 3 morula and 0.335±0.039 mcu with day 3 blastocyst. Day 1 and day 4 to 5 embryos (uncleaved ova and hatched blasocysts, respectively), incubated in the same way, produced only partial liquefaction of the fibrin drops. 2. When applied directly on plasminogen-rich fibrin plates, day 3 ova (morulae) produced grossly recognizable fibrinolysis. No lysis was observed on application of day 3 ova on plasminogen-free fibrin plates. Five μl medium drops incubated with day 3 embryos were applied on both kinds of fibrin plates and gave similar results.

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Although there are many reports of sperm chromatin decondensation within eggs, only two reports have shown this observations with the use of the electromicroscopy. Nobody has shown the process of human sperm chromatin decondensationwith the continous observations of living ooplasma. Our previous report hasshown that calmodulin antagonist W-7 can stimulate the acrosome reaction of humansperm, and that these sperm are capable of penetrating zona-free hamster eggs. This study has shown the contious observations of chromatin decondensationof human sperm treated with W-7 by means of zona-free hamster eggs. Althoughvarious patterns of decondensation were recognized, almost all of the sperm showedthe following: 1) the brightness of the post acrosomal region was lost just beforedecondensation began, 2) chromatin dispersion began at the anterior, one-third ormid lateral region of the post acrosome, 3) the bright area origenated from thispost acrosomal region and gradually increased, 4) the decondensation of the postacrosomal region was more rapid than the acrosomal region, 5) the oval shapedring formation was shown to be a remaining chromatin mass by Nomarski InterferenceMicroscopy, and was recognized at the apex area of the acrosome, 6) the peripheralring formation, : appeared around the oval shaped ring formation which was fusingin the front and rear. This ring formation was observed for a period of approximately2 to 5 minutes after the oval shaped ring formation disappeared. From these observations, we suggest that the mechanism of human sperm chromatindecondensation does not resemble other mammalian sperm chromatin decondensationon the basis of such ring formation.

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Experiments were designed to test the effects of simple sugars andcomplex polysaccharides on the attachment of human spermatozoa withthe zona pellucida. For this in vitro system the salt-stored humaneggs (Yanagimachi et al. 1979) were used.The attachment of capaciated spermatozoa to the zona pellucida wasinhibited by fucoidin. Fucoidin was a very potent inhibitor, completelyblocking attachment at a concentration of 0.1 mg/ml.When the spermatozoa were treated with 1 mg/ml fucoidin and weremixed with ova in fucoidin-free medium, they barely attached to thezona. However, pretreatment of the zonae identicaly, prior tomixing with untreated spermatozoa, did not inhibit attachment.These results suggest that fucoidin probably reacted with spermatozoa, not with zonae.

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The surface of the zona pellucida from unfertilized and fertilized mouse ovawas examined with the scanning electron microscope (SEM) The zona of amature unfertilized ovum showed a sponge-like appearance with numerous fenestrations, Up to 5 hours after fertilization no change was observed in this structure, except for sperm penetration hole which remained almost unchangedeven after cleavage The zona of 2-cell embryo was considerably smoother and aporous appearance was much less obvious. SEM detectable surface change inthe mouse zona pellucida may be due to the precipitates of tubal secretions.

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ウシの胚盤胞14個について染色体の検出を試みた。その結果、11個 (78, 6%) の受精卵に中期核板がみられ、4個 (28, 6%) の受精卵で性別判定が可能であった。しかし、ウシの受精卵には中期核板が少なく、さらに染色体の収縮が起こるため、Y染色体の識別は困難であった。以上の結果から、ウシの受精卵の染色体検査を行う場合には、さらに培養条件の検討が必要と考えられた。

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イオノフオアA23187で処理しなヤギ精子のcapacitation, acrosomereactionおよびhyperactivationを透明帯除去ハムスター卵子を用いてしらべた。卵子はイオノブオア処理後インキュベーションなしに、あるいはパラフインオイル下のBO液での37℃, 0.5-4.O時間のインキュベーションののち媒精された。イオノフオア処理精子では、acrosomereactionとhyperactivationはほぼ同時に起きたが、その後、処理精子の透明帯除去ハムスター卵子への侵入能は、速やかに低下した。イオノフオア処理精子は雌生殖器内でプリインキュベーションした精子に比べて、早いcapacitationとacrosome reactionが誘起された。

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JCL-SD系幼若雌ラット (24-27日齢) に7.5, 15または30IUPMSGと10IUHCGを56時間間隔て投与し、HCG投与16-16.5時間後に卵管膨大部より卵子を採取し、体外受精によって受精能を検討した、, 精子は同系統の成熟雄 (30週齢以上) の精巣上体尾部から採取し、0.4×10精子/mlとなるように希釈し4.0-4.5時間プレィンキュベートした。卵子は卵丘細胞層に包まれたままの状態で精子液中へ導入後7-8時間に透明帯への精子侵入、卵細胞質内の精子の有無および多精子受精について位相差顕微鏡下て検査した。7.5, 15および30IUPMSG投与区における平均排卵数は、7.0.14.6および23.1であった.受精率は、それぞれ100、91.3および76.9%であり、30IU投与区は15IU区に比べて有意に低い値であった。多精子受精率は、それぞれの投与区で14.3, 17.7および27.5%で、投与量の増加に伴って上昇する傾向を示した。これらの結果から、PMSGによる卵巣の過度の刺激は、排卵卵子の受精能力を低下させることが示唆された。

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