PubMed Health⌕ Search

Biomedical subjects

P G Calarco

Publications and source records attributed to P G Calarco.

At least 37 records · Page 2Linked to original sources
PubMed1979

Intracisternal A particles in preimplantation embryos of feral mice (Mus musculus).

In embryos of feral mice, intracisternal A particles (IAP) are not observed in zygotes, but large numbers are seen budding into the endoplasmic reticulum at the 2-cell stage. In subsequent cleavage stages very few IAP are present. Organelles and developmental changes in organelles during the preimplantation period are characteristic of those described previously in embryos of laboratory mice.

Animals↗
PubMed1977

Alkaline phosphatase activity in the preimplantation mouse embryo.

Alkaline phosphatase (AP) activity has been assayed in frozen sections of preimplantation mouse embryos by an azo-dye cytochemical method. The results indicate that during preimplantation mouse development AP activity is first expressed between the 8- and 16-cell stages and develops in all cells by the late morula stage. During blastocyst formation AP activity is lost or greatly reduced in trophoblast cells while activity is maintained in the inner cell mass.

Alkaline Phosphatase↗
PubMed1976

Ultrastructural observations of preimplantation stages of the sheep.

Sheep embryos were examined with the electron microscope in order to characterize their organelles and the changes that occur during the preimplantation period. The first sign of differentiation of trophoblast cells was the appearance of junctions between external cells at the 16-cell stage. Nucleoli developed a granular component suggesting the synthesis of ribosomal RNA at the 16-cell stage also. Centrioles were seen as early as the 8-cell stage. Intracytoplasmic vesicles were present in large numbers in all cleavage stages but disappeared at blastulation. Mitochondria progressed from a very electron-dense hook- or U-shaped form with a few cristae to a cylindrical or spherical form of light density with many transverse cristae. Microvilli were not seen until the blastocyst stage and then only on the exterior surface of the trophoblast cells. Crystalloid or virus inclusions were not observed. It was concluded that the fine structure and developmental changes in the early sheep embryo are very similar to those of other mammalian species.

Animals↗
PubMed1976

Ultrastructural observations of lethal yellow (Ay/Ay) mouse embryos.

Ay/Ay embroys were identified by the presence of large exluded blastomeres (Pedersen, 1974) and examined cytologically and ultrastructurally. Cell organelles, inclusions and junctions in the excluded blastomeres were compared with those of non-excluded cells of Ay/Ay embryos and control embryos. Excluded blastomeres always had the fine structural characteristics of earlier developmental stages and may have arrested at the 4- to 8-cell stage of slightly later. Interior cells (inner cell mass) were observed in all mutant blastocysts. Non-excluded cells of Ay/Ay embryos were normal until degenerative changes appear in the late blastocyst stage. The mode of action of the +Ay gene was not determined, but evidence from this study and others indicate that the effects of +Ay gene action occur over a wide range of time in early cleavage and implantation.

Alleles↗