Uterine proteins and the activation of embryos from mice during delayed implantation

Abstract

Summary. Ovariectomy-induced delay of implantation was used to study the role of the uterine environment in controlling implantation in mice. Labelling studies in vivo showed that uterine protein synthesis and secretion is maximal 2\p=n-\5h and 24\p=n-\30h after the oestradiol injection which initiates implantation. Embryos removed from uteri 5,12 or 30 h after oestradiol injection were able to transport and utilize precursors of nucleic acids and proteins in short-term cultures at the same rate as normal embryos, although 'delayed' embryos had low levels of activity. These results suggest that 'delayed' embryos are metabolically activated within 5 h of release from delay, perhaps because of the hormonally-induced changes in uterine proteins which occur at this time.

Whole protein uptake and metabolism by mouse blastocysts

“…In other cells, this process occurs by lysosomal activity and the only labelled product is 125I-labelled tyrosine (Livesey & Williams, 1981;Kooistra & Lloyd, 1985). Further Aitken, 1977;Pratt, 1977) and volume (~4 pi Edirisinghe & Wales, 1980; 0-2 pi: Hoversland & Weitlauf, 1981) of flushings of mouse uteri yield an estimated protein concentration of about 10 mg/ml, which is close to that found for rabbit oviduct fluid (5 mg/ml: Shapiro, Jentsch & Yard, 1971). The uptake rate at this concentration (Fig.…”

On the source of uterine 'luminal fluid' proteins in the mouse

“…Samples of such proteins are usually obtained by flushing the lumen (Surani, 1975(Surani, , 1977 Gore-Langton & Surani, 1976;Pratt, 1977;Aitken, 1977). I had been puzzled by the large amounts of material so obtained from mouse uteri on Days 4-5 of pregnancy, because at this time the lumen virtually disappears, the luminal epithelial surfaces coming into such close proximity that the microvilli of the opposing surfaces interdigitate or disappear (Mayer, Nilsson & Reinius, 1967;.…”

Phospholipid synthesis in the preimplantation mouse embryo

“…The present study of phospholipid synthesis in the preimplantation mouse embryo used [methyl-3H]choline as a specific precursor for choline-containing phospholipids, one of the major classes of phospholipids (Bergeron, Warmsley & Pasternak, 1970;Rothman & Lenard, 1977 The labelling medium consisted of embryo culture medium + 4 mg bovine serum albumin (BSA)/ml (Biggers, Whitten & Whittingham, 1971) Acid-insoluble radioactivity was determined by depositing the material on GF/C filters, washing and drying the filters in the conventional manner (Pasternak, 1973;Pratt, 1977) (Pasternak, 1973); (2) the radioactivity was resistant to proteolytic digestion by pronase; and (3) 100% of the [methyl-3H]choline-labelled material could be recovered from the thin-layer plates as phospholipids. Individual phospholipids were identifiable by their susceptibility to alkaline hydrolysis (Dawson, 1960) and treatment with phospholipase C (Simpson & Hauser, 1966).…”