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At least 127 records · Page 7Linked to original sources
PubMed1996

In vitro analysis of epiblast tissue potency for hematopoietic cell differentiation.

In murine embryogenesis, all cells that will constitute the embryonic structures originate from the epiblast (primitive ectoderm) tissue, the epithelial cell sheet of the gastrulating embryo. The cells of this tissue are totipotent at the beginning of gastrulation, but at the end of this period are specified to particular cell lineages. Thus, it is likely that during murine gastrulation, the potency of epiblast cells that were originally totipotent becomes restricted as development progresses. However, the mechanisms of this process are unknown. We have investigated this process in vitro, focusing on the hematopoietic cell lineage. To detect the hematogenic potency of the epiblast tissue, we established an in vitro culture system in which the hematopoietic cell differentiation of the epiblast tissue was supported by a stromal cell layer. With this culture system, we investigated the process by which this potency becomes spatially and temporally restricted during gastrulation. The results showed that hematogenic potency resides in the entire epiblast of the early- to mid-gastrulating embryo, but becomes restricted to the posterior half of the epiblast at the headfold stage. Furthermore, we showed that this process is altered by exogenous bone morphogenetic protein-4 (BMP-4) or activin A, which may be mesoderm inducers in Xenopus embryogenesis.

Activins↗
PubMed1976

Uterine proteins and development in vitro of rabbit preimplantation embryos.

The effects of isolated protein fractions from rabbit uteri (prealbumin, albumin, uteroglobin, and beta-glycoprotein), unfractionated uterine proteins, progesterone, oestradiol-17beta, and prostaglandin F-2a on the development of rabbit embryos in vitro were investigated. When exposed to individual protein fractions obtained from Day-6 uteri, 8-cell embryos did not develop into early blastocysts; morulae readily developed into early blastocysts, but further development was retarded. Progesterone (10(-5)-10(-11)M) and prostaglandin F-2a (0-1-10 ng/ml) added to the medium slowed development of blastocysts to advanced stages. Growth of 8- to 16-cell embryos, morulae, and Day-4 blastocysts was stimulated by unfractionated uterine proteins obtained from Day-5 uterine flushings. Although embryos cultured in medium containing BSA had similar rates of blastocyst formation and, ultimately similar blastocyst expansion as did the embryos cultured in medium with unfractionated proteins, the radial and immediate expansion of the early blastocysts cultured in the latter approximated that found in utero.

Albumins↗
PubMed1976

The effect of maternal cytomegalovirus infection on preimplantation development in the mouse.

Mice were inoculated with murine cytomegalovirus at 14 and 7 days before and 1 and 4 days after mating. The effects of maternal infection on early pregnancy were investigated. Inoculation 7 days before and 1 day after mating, i.e. around ovulation and implantation, significantly reduced pregnancy rate. Embryos in these females were developmentally retarded, perhaps because of the inflammatory effect of the infection on the genital tract. Retarded embryos developed normally when cultured.

Animals↗
PubMed1976

Effect of removal of epididymal secretions on fertilization in vitro of mouse eggs.

The removal by centrifugation of epididymal contents from mouse spermatozoa had no deleterious effect on fertilization in vitro, and, depending on the genotype of the gametes, was frequently associated with increased levels of fertility. Washing of the spermatozoa significantly improved the fertilization rate of F1 eggs with TO spermatozoa and of BALB/c eggs with BALB/c spermatozoa, but had no significant effect of F1 spermatozoa with F1 eggs.

Animals↗
PubMed1978

In-vitro fertilization of preovulatory human eggs.

Preovulatory eggs were aspirated from the ovaries of women 36-38 h after hCG and incubated with washed sperm suspensions for 3 or 6 h; 5 out of 9 eggs were fertilized. Sperm penetration into the ooplasm and decondensation of the male chromatin was observed by 3 h, and an early pronucleate egg was found by 6 h, suggesting that human spermatozoa may become capacitated in vitro in 3-4 h.

Ectogenesis↗
PubMed1978

Correlation between cytological and morphogenetic effects of acute X-irradiation of preimplantation mouse embryos cultured in vitro.

Inhibition of cavitation by acute X-irradiation of 2-cell stage eggs was due to the early killing of the cells. Eggs in which cavitation did take place had a smaller number of cells due mainly to mitotic delay, leading to lack of inner cell mass (ICM) and its derivatives in further development. A similar effect is responsible for the inhibition of ICM formation after irradiation of morulae.

Animals↗
PubMed1978

In-vitro development of preimplantation embryos recovered from IUD-bearing mice.

Embryos were collected from the oviducts and uterine horns of mice bearing a unilateral IUD and of non-IUD control mice at various times p.c., examined for the presence or absence of polymorphonuclear leukocytes (PMNLs) and cultured. Normal numbers of embryos were obtained on the IUD side at 48 h p.c., but reduced numbers were recovered at 60-66 and 72 h p.c. The numbers of embryos that hatched from those collected from control, IUD-bearing and contralateral non-IUD bearing tracts were, respectively, 81, 29 and 36% for 48-h embryos, 78, 47 and 51% for 60-66-h embryos, and 88, 47 and 54% for 72-h embryos. At 48 h and 60-66 h p.c. the arrest of development occurred at the expanded blastocyst stage, but at 72 h p.c. some compacted morulae were affected. Some embryos associated with PMNLs at collection developed normally when the PMNLs were dispersed before culture. An initial association with leukocytes is therefore not necessarily detrimental to the subsequent in-vitro development of the embryo in mice.

Animals↗
PubMed1980

Histamine formation by mouse preimplantation embryos.

Mouse embryos recovered on the 4th day of pregnancy produced histamine, as evidenced by the 14CO2 produced from carboxy labelled L-histidine, at the rate of 1.5 +/- 0.3 (s.e.m.) pmol/embryo per hour. Most (83.2 +/- 4.6%) of the embryos flushed from the oviducts on Day 3 of pregnancy (4--8-cell stage) developed into blastocysts within 48 h after being placed in culture. Inclusion of L-histidine hydrochloride (4.7 x 10(-4) M) in the culture medium did not alter this development but DL-alpha-methylhistidine (3.8 x 10(-4) M), an inhibitor of histidine decarboxylase, reduced the number of embryos developing into blastocysts to only 10.8 +/- 6.8%. A combination of L-histidine and DL-alpha-methylhistidine in the medium prevented the growth-retarding effect of the latter compound. The results indicate that mouse embryos can produce histamine and suggest that this is necessary for normal development.

Animals↗
PubMed1980

The role of commercial bovine serum albumin preparations in the culture of one-cell rabbit embryos to blastocysts.

Normal bovine serum albumin (BSA) in a complete medium without energy substrates promoted growth of 1-cell embryos to hatched blastocysts. Defatted charcoal-treated BSA did not promote growth to the blastocyst stage but the addition of pyruvate or palmitic and oleic acids allowed blastocyst growth but not blastocyst hatching. Sodium dodecyl sulphate-gel electrophoresis showed that both the normal and defatted BSA samples were heavily contaminated by proteins other than albumin. Fractionation of the normal BSA on Sephadex G-200 indicated that the property of promoting complete blastocyst hatching was not due to the albumin but was associated with the higher mol. wt fraction of the BSA. Extraction of normal BSA with chloroform appeared to destroy the hatching-promoting ability as neither the residue after extraction nor defatted BSA to which the organic extractate had been added promoted complete blastocyst hatching. It is concluded that commercial BSA may have at least two effects on blastocyst growth: (1) energy provision via albumin-bound fatty acids, and (2) promotion of blastocyst hatching by a non-albumin component.

Animals↗
PubMed1983

Variability in different lots of commercial bovine serum albumin affects cell multiplication and hatching of rabbit blastocysts in culture.

Rabbit morulae were cultured in vitro for 4 days in a synthetic culture medium supplemented with two different lots of commercial bovine serum albumin (BSA) and two different amino acid formulations in a factorial 2 x 2 arrangement. One lot of BSA caused complete hatching of a proportion of blastocysts and formation of more than twice as many cells per blastocyst (hatched and unhatched) as that of the second BSA lot which did not cause complete hatching of any blastocysts. The mean cell numbers of hatched blastocysts were more than twice those of non-hatched blastocysts. There was no significant effect of amino acid formulation.

Animals↗
PubMed1976

[The histogenesis of somites in the chick].

The somites of the thoracic region of chick embryos incubated for 2 (stages 13-15) and 3 days (stages 17-19) have been examined cytologically and ultrastructurally. Cell contacts and cell arrangement were studied first in spherical somites. The further development of the spherical somite is characterized by changes in the cell arrangement. According to these changes two somitic cell populations can be distinquished: a ventral one, which during the third day loses its epithelial arrangement and becomes disaggregated, and a dorsal one, the dermatome, which remains spithlial for a longer time. Some cells of the ventral group reaggregate on the apical surface of the dermatome cells, and constitute the myotome. The contacts between dermatome and myotome cells as well as between the myotome cells themselves are described. Although the myotome cells appear to be arranged in an epithelial-like order and develop a basement membrane at the sclerotome side, the characteristic contacts and cell polarity of epithelia were not observed. These observations are discussed in relation to the process of cell adhesion and cell communication during the morphogenesis of the secondary mesenchyme.

Animals↗
PubMed1978

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Animal Experimentation↗