Publisher Correction: Self-assembly of embryonic and two extra-embryonic stem cell types into gastrulating embryo-like structures.

In the version of this Technical Report originally published, the competing interests statement was missing. The authors declare no competing interests; this statement has now been added in all online versions of the Report.

Self-assembly of embryonic and two extra-embryonic stem cell types into gastrulating embryo-like structures.

Embryonic stem cells can be incorporated into the developing embryo and its germ line, but, when cultured alone, their ability to generate embryonic structures is restricted. They can interact with trophoblast stem cells to generate structures that break symmetry and specify mesoderm, but their development is limited as the epithelial-mesenchymal transition of gastrulation cannot occur. Here, we describe a system that allows assembly of mouse embryonic, trophoblast and extra-embryonic endoderm stem cells into structures that acquire the embryo's architecture with all distinct embryonic and extra-embryonic compartments. Strikingly, such embryo-like structures develop to undertake the epithelial-mesenchymal transition, leading to mesoderm and then definitive endoderm specification. Spatial transcriptomic analyses demonstrate that these morphological transformations are underpinned by gene expression patterns characteristic of gastrulating embryos. This demonstrates the remarkable ability of three stem cell types to self-assemble in vitro into gastrulating embryo-like structures undertaking spatio-temporal events of the gastrulating mammalian embryo.

Reproductive Performance after Unilateral or Bilateral Oviduct Transfer of 2-Cell Embryos in Mice.

Embryo transfer (ET) is a frequent procedure in contemporary animal and transgenic facilities. We compared the reproductive performance of mice after unilateral and bilateral ET of 15 to 18 two-cell embryos per recipient. The genetic backgrounds of the donors were C57BL/6J (B6J), C57BL/6N (B6N), or fewer than 5 generations of backcrossing to B6 (unknown substrain, <5G B6). The pregnancy rate was significantly higher for bilateral than for unilateral ET for B6J lines (85.4% compared with 79%) but similar between modes for B6N (73.7% compared with 77.9%) and <5G B6 (77% compared with 74.5%) lines. The birth rates after unilateral and bilateral ET were 30.8% and 33.0% for B6J lines, 24.5% and 26.9% for B6N lines, and 31.0% compared with 28.2% for <5G B6 lines, with no significant difference between the modes of ET. Birth rate was significantly higher for B6J lines than B6N lines after both unilateral and bilateral ET. For B6J and B6N lines, the number of pups born per litter was significantly higher for bilateral than unilateral ET. Unilateral ET yielded 0.24 to 0.31 pup per embryo transferred compared with 0.27 to 0.33 pups after bilateral ET. Over all genetic backgrounds, 3.03 to 4.09 embryos were required to produce a single pup. The present study provides data to aid in decision-making as to whether unilateral or bilateral ET should be performed. Bilateral ET results in a larger litter but increases pain and discomfort in recipients. However, unilateral ET saves time and contributes to refinement because surgical trauma is reduced.

Productivity of superovulated C57BL/6J oocyte donors at different ages.

Superovulation is often used to increase the number of oocytes that can be collected from donor females for in vitro fertilization. Donor age can affect the quantity and quality of oocytes produced during superovulation, and in some strains of mice juvenile females are optimal donors. The authors reviewed donor and oocyte records from a breeding program to evaluate how donor age affects the number and fertilization efficiency of oocytes collected from C57BL/6J mice. Generally fewer oocytes per donor were collected from females aged > 32 d than from females aged 21-32 d. Fertilization efficiency of oocytes generally declined with donor age when oocytes were fertilized with fresh or with stored sperm. These findings suggest that the use of younger C57BL/6J donors, instead of older donors, can reduce the number of donors needed for IVF procedures.

Levels of CEA and Ca 19 - 9 in the sera and peritoneal cavity in patients with gastric and pancreatic cancers / Níveis de CEA e Ca 19 - 9 em soro e cavidade peritoneal em pacientes com câncer do estômago e pâncreas

PURPOSE: Tumor markers are substances found in blood and other biological fluids if tumor is present in the body. They can be produced by tumor itself or can be results of cancer - body relation. They may be used in the follow-up of cancer patients to identify tumor recurrence. Pre-treatment levels have prognostic tool and could signalize persistence of minimal residual disease despite radical surgery. METHODS: We operated on 52 patients with upper GI malignancy (32 with gastric cancer and 20 with pancreatic cancer). Blood samples were taken before surgery and peritoneal samples immediately after laparotomy before any manipulation with tumor. All samples were examined by standard biochemical technique and the level was compared with a stage of the disease. RESULTS: Patients suffering from gastric carcinoma of stage I and II had higher level of both markers in sera then in the peritoneal cavity, however most of them were within physiological range. Patients in stage III and IV had average marker levels in the peritoneal cavity higher than in sera. Number of positive findings was increasing according to the stage of the disease. The peritoneal levels of both markers varied extremely in higher stages. In patients suffering from pancreatic carcinoma the CEA levels both in sera and peritoneal cavity were parallel but peritoneal levels were slightly higher in stages III and IV. Ca 19 - 9 was more sensitive for pancreatic cancer. The percentage of positive findings was higher in sera but the level of Ca 19 - 9 was higher in the peritoneal cavity. The number of positive findings again correlated with the stage of the disease. CONCLUSIONS: Levels of tumor markers in sera could signalize inoperability of tumor (Ca 19 - 9 in cases of pancreatic carcinoma); peritoneal levels could predict R1 resection especially in gastric cancer patients and risk of early peritoneal recurrence of the disease. Difference between the levels in the peritoneum and sera may signalize the route of dissemination (hematogenous and intraperitoneal).

OBJETIVO: Os marcadores tumorais são substâncias encontradas no sangue e outros fluidos biológicos em pacientes com doenças oncológicas. São produzidos pelo próprio tumor ou ser resultado da interação entre o tumor e o organismo. Podem ser usados no seguimento de pacientes com câncer para identificar recidiva tumoral. Os níveis pré-tratamento têm valor prognóstico e podem sinalizar persistência de doença residual mínima após cirurgia radical.. MÉTODOS: Foram operados 52 pacientes com tumores do trato gastroinstestinal superior (32 com câncer do estômago e 20 do pâncreas). Amostras sanguineas foram colhidas no préoperatório e amostras peritoneais imediatamente após a laparotomia, antes de qualquer manipulação do tumor. Todas as amostras foram examinadas bioquímicamente e os resultados foram comparados entre si e em face ao progresso da doença. RESULTADOS: Os pacientes com câncer de estômago nos estadios I e II apresentaram níveis sanguineos mais elevados de ambos os marcadores tumorais do que no peritônio, mas a maioria dos valores encontrava-se dentro dos limites fisiológicos. Já nos estadios III e IV os níveis dos marcadores tumorais foram mais elevados no peritônio do que no sangue. O número de exames positivos aumentou de acordo com o estadio da doença. Nos estádios avançados, observou-se elevada variabilidade nos níveis de ambos os marcadores analisados no peritônio. Os doentes com carcinoma de pâncreas tiveram níveis de CEA semelhantes no sangue e no peritônio, mas os níveis peritoneais foram ligeiramente mais elevados nos estadios III e IV. Ca 19 - 9 foi muito mais sensível para o câncer do pâncreas. A porcentagem de exames positivos foi mais elevada no sangue, mas o níveis do Ca19-9 foram mais elevados no peritônio.A porcentagem de exames positivos também teve correlação com o estadio da doença. CONCLUSÕES: Os níveis de marcadores tumorais no sangue podem indicar inoperabilidade do tumor. No peritônio podem indicar o tipo de ressecção, especialmente nos doentes com câncer gástrico, e o risco de recidiva peritoneal precoce. A diferença entre os níveis no peritônio e sangue podem sinalizar a via de disseminação, hematogênica ou intra-peritoneal.