Embryo implantation and proteinase activities in a marsupial (Macropus eugenii)

Summary Embryo implantation remains superficial (epithelio-chorial type) in most marsupials including the Macropodidae, but does involve formation of specialized contact zones of the trophoblast with the uterine epithelium. Since in eutherian mammals proteinases appear to play a central role in implantation-initiation mechanisms, a systematic histochemical investigation of proteinase patterns as related to implantation was performed in the tammar wallaby, Macropus eugenii (Macropodidae).Tammar uteri with embryos were collected at diapause and at days 7, 17, 18, 19, 20, 21 and 26 of the 27-day gestational period. Proteinase patterns were studied using a sensitive histochemical gelatin-substrate-film test previously optimized for the detection of trophoblast-dependent proteinase (blastolemmase) in the rabbit. Proteinase patterns were correlated with light-microscopical morphology of the processes of shedding of the extracellular embryo coverings (shell membrane) and attachment of the trophoblast to the uterine epithelium.At acid pH values an intracellular proteinase is detected in yolk sac endoderm and trophoblast as well as in endometrial glands and certain stromal cells. This enzyme is proposed to be a cathepsin indicating high catabolic activity connected particularly with protein transport from the endometrium into the yolk sac. Peak activity is found in the avascular (bilaminar) yolk sac at the phase when contact with the endometrium is being established.A particularly interesting proteinase active at alkaline pH values is detected in the trophoblast-endoderm complex. This enzyme appears to be extruded into the interface between trophoblast and uterine epithelium where it shows maximal activity for only approximately one day, around day (18-)19, exclusively in the bilaminar (avascular) yolk sac. The activity is correlated with the process of shedding of the extracellular embryo coverings (shell membrane) and of subsequent attachment of the trophoblast to the uterine epithelium, in the bilaminar but not the trilaminar (vascular) yolk-sac region. This is the first report on an extracellular (alkaline) proteinase activity possibly serving a specific function in embryo implantation in a marsupial.Abreviations BYS bilaminar (avascular) yolk sac membrane = bilaminar omphalopleure - dp.c. days post coitum - d RPY days after removal of pouch young - TYS trilaminar (vascular) yolk sac membrane = trilaminar omphalopleure Preliminary reports on portions of these investigations were presented at the 14th Annual Meeting of the Society for the Study of Reproduction 1981 (Biol Reprod 24 Suppl 1, p 78 A, 1981) and at the 3. Arbeitstagung der Anatomischen Gesellschaft 1982 (Anat Anz 153, 268, 1983)     

Embryo implantation associated with increase in T-cell suppressor factor in the uterus and spleen of mice

The concentrations of T-cell suppressor factor (TsF) were examined by competitive binding assays in the uterus, spleen, and regional lymph nodes draining the uterus in Day-5 pregnant mice or in ovariectomized mice given hormone treatments to induce conditions of delayed implantation or implantation. The amounts of immunoreactive TsF on Day 5 of pregnancy were 2.055 +/- 0.302, 0.803 +/- 0.088, 0.426 +/- 0.136 ng TsF/mg extractable protein for the regional lymph nodes, spleen and uterus, respectively, during Day 5 of pregnancy. When implantation was prevented by ovariectomy on Day 4 followed by treatment with only progesterone, amounts of TsF (as a % of Day 5 value) were decreased to 57% in the uterus and increased to 141% in the spleen and 180% in the regional lymph nodes. When implantation was then initiated with the addition of oestradiol-17 beta to the progesterone treatment, amounts of TsF were increased to 206% in the uterus, 318% in the spleen, and remained unchanged at 180% in the regional lymph nodes. These experiments suggest that the amounts of TsF in the uterus and spleen are dependent upon the implantation process, whereas amounts of TsF in the regional lymph nodes are independent of this event.     

Embryo spacing and implantation timing are differentially regulated by LPA3-mediated lysophosphatidic acid signaling in mice

In polytocous animals, blastocysts are evenly distributed along each uterine horn and implant. The molecular mechanisms underlying these precise events remain elusive. We recently showed that lysophosphatidic acid (LPA) has critical roles in the establishment of early pregnancy by affecting embryo spacing and subsequent implantation through its receptor, LPA3. Targeted deletion of Lpa3 in mice resulted in delayed implantation and embryo crowding, which is associated with a dramatic decrease in the prostaglandins and prostaglandin-endoperoxide synthase 2 expression levels. Exogenous administration of prostaglandins rescued the delayed implantation but did not rescue the defects in embryo spacing, suggesting the role of prostaglandins in implantation downstream of LPA3 signaling. In the present study, to know how LPA3 signaling regulates the embryo spacing, we determined the time course distribution of blastocysts during the preimplantation period. In wild-type (WT) uteri, blastocysts were distributed evenly along the uterine horns at Embryonic Day 3.8 (E3.8), whereas in the Lpa3-deficient uteri, they were clustered in the vicinity of the cervix, suggesting that the mislocalization and resulting crowding of the embryos are the cause of the delayed implantation. However, embryos transferred singly into E2.5 pseudopregnant Lpa3-deficient uterine horns still showed delayed implantation but on-time implantation in WT uteri, indicating that embryo spacing and implantation timing are two segregated events. We also found that an LPA3-specific agonist induced rapid uterine contraction in WT mice but not in Lpa3-deficient mice. Because the uterine contraction is critical for embryo spacing, our results suggest that LPA3 signaling controls embryo spacing via uterine contraction around E3.5.     

Embryo implantation is closely associated with dynamic expression of proprotein convertase 5/6 in the rabbit uterus

Background  

Proprotein convertase 5/6 (PC5/6) is critical for embryo implantation in women, regulating both uterine epithelial receptivity and stromal cell decidualization. PC5/6 is likewise essential for implantation in mice, but involved only in decidualization. An alternative animal model is required to address the function of PC5/6 in the uterine epithelium. This study aimed to establish whether PC5/6 is associated with embryo implantation in rabbits.     

多花地宝兰胚囊和胚发育的细胞学研究

为探讨多花地宝兰(Geodorum recurvum)胚胎发育的系统分类学意义,采用石蜡制片法对多花地宝兰胚囊和胚的发育进行解剖学观察。结果表明,在开花前,多花地宝兰胚珠原基发育缓慢,开花授粉后胚珠原基快速发育成"树状二杈分枝结构",随后在"分枝结构"末端形成孢原细胞,开始胚囊发育。多花地宝兰的胚囊发育属于单孢蓼型胚囊,胚珠具有双层珠被。孢原细胞形成后,经过细胞膨大延长发育形成胚囊母细胞,胚囊母细胞经过减数分裂形成线性四分体,在珠孔端形成1个功能大孢子,功能大孢子经过3次有丝分裂形成8核胚囊。多花地宝兰的胚发育具有藜型和紫苑型两种方式。双受精完成后,多花地宝兰合子进行一次橫裂后形成基细胞和顶细胞;基细胞经过多次分裂形成细胞团,细胞团中的细胞向不同方向膨大延长形成多个胚柄细胞;顶细胞有两种分裂方式,一种是横裂形成藜型胚,一种是纵裂形成紫苑型胚。因此,推测多花地宝兰在兰科植物系统分类学上属于较为原始种。     

Embryo recovery in swine

Embryos were surgically recovered 63 times from 13 purebred donor sows for an average of 4.8 times per donor. Recoveries were completed at three or six week intervals. An average of 15.6 transferable embryos were collected per surgery. Based on these limited observations it would appear that multiple surgical embryo recoveries may be completed on a specific donor at three and/or six week intervals without impairing future production.     

Insect Embryo Chromosome Techniques

The whole-mount method for studying chromosomes of insect eggs is used; the eggs are caused to adhere to cover glasses, which are handled in racks especially designed for carrying large numbers. A basic and helpful change in the usual technique after fixation and before staining involves extraction of the material 1 hr to overnight with a 1:1 methanol-chloroform mixture to remove plasmal-reactive substances. Either leucobasic fuchsin or sulfonated azure A after acid hydrolysis may be used satisfactorily to stain the chromosomes.     

Embryo Transplantation in Cattle

Previous attempts to transfer embryos non-surgically to heifers have been rather discouraging. The present experiment describes a simple non-surgical technique where the 6½–7½ -day old embryo is placed in a 0.25 ml ministraw, fitted into a common insemination gun and transferred cervically to synchronized lactating dairy cows. Thirty-two viable embryos were transferred to the middle part of the uterine horn ipsilateral to the ovary containing the corpus luteum. It was easy to pass the cervix, and most embryos could be deposited in the horn within 1 or 2 min. Eighteen animals were diagnosed pregnant (56% ). It is conceivable that the easy atraumatic transfers and good management (feeding, oestrus control) of the recipients contributed to the high pregnancy rate.