Biomedical subjects

M Guillomot

Publications and source records attributed to M Guillomot.

28 records · Page 2Linked to original sources

PubMed1988

Embryo-uterine interactions during early stages of pregnancy in domestic mammals.

The first part of this paper presents data concerning our knowledge of uterine proteins during early pregnancy in domestic mammals; the second part gives results of in vitro biochemical studies on embryo-uterine interactions in the ewe. We have developed an in vitro technique of the co-culture of ovine uterine epithelial cells with the blastocyst or its secretory proteins. The effects of a specific trophoblastic protein (oTPB), involved in the maintenance of the corpus luteum, have been particularly studied by this system. The modifications of endometrial protein synthesis have been measured by incorporation of radiolabelled amino acids and analysed by electrophoresis (SDS-PAGE or bidimensional). The results show that the presence of the blastocyst, or of its total secretory proteins or oTPB alone, decreased overall protein synthesis by the endometrial cells. The nature of the secreted proteins was apparently not affected by the blastocyst, but the addition of oTPB alone increased the production of 3 polypeptides (MW = 150.10(3); 74.10(3); 50.10(3) and pI = 7-8.2; 5.4-5.2; 6.4, respectively) and decreased the synthesis of 2 others (MW = 57.10(3); 35.10(3) and pI = 7-6.7; 5.3, respectively). We also studied the effects of co-culture with uterine cells on blastocyst DNA and protein synthesis. In no cases we obtained stimulation of blastocyst development during the co-culture period, and DNA or protein synthesis decreased in the presence of uterine cells. In conclusion, the presence of specific uterine proteins has been established in some domestic mammals (pig, rabbit) but not in all of them. Although local modifications of uterine protein synthesis are induced by the embryo or its secretory products, the nature and the role of the proteins which are affected need to be determined by further studies.

Animals↗

PubMed1988

[Trophoblastic proteins].

Many studies conducted on human or animal placenta (chorion) suggest that the trophoblast is not only a passive filter between maternal and foetal blood flow, but is also endowed with complex functions. Factors of trophoblast origin involved in the mechanism of pregnancy recognition or maintenance of the progesterone environment required for the embryo survival, are reviewed. The main proteins involved in pregnancy are reported in table 1. Emphasis is laid on early signals of pregnancy which are of practical interest in human clinical medicine and animal husbandry. Among them, human chorionic gonadotropin (hCG), protein SP1 ("Schwangerschaftsprotein" 1) and some pregnancy-associated plasma proteins such as the PAPP A are very useful in the diagnosis of pregnancy, abortion, foetal abnormality or tumor in the human species. The presence of trophoblastin (presently studied in our laboratory) of a pregnancy-specific protein B and of early pregnancy factor (EPF) attest the establishment of pregnancy in domestic animals and in other mammals. The biological properties of some hormones such as placental lactogens (PL) or chorionic somatomammotropins (CS), human placental growth hormone (hPGH) contribute to a better understanding of the gestation function. Many other factors participate in the foetal development, for example, proliferin. Some proteins can display immunosuppressive properties or be responsible for the immune tolerance between the mother and the foetus. Although many placental proteins have already been defined, their biological functions have not yet been elucidated.

Animals↗

PubMed1987

Equine zona pellucida and capsule: some physicochemical and antigenic properties.

The capsule which surrounds the pre-attachment equine embryo has been compared with the zona pellucida (zp) that it replaces, as well as with the rabbit blastocyst coverings, by means of physicochemical and immunological methods. Trypsin solution at pH varying between 7.5 and 9.0 completely solubilized the capsule, as did Na borohydride. However, solutions of pH 2.0 or 12.0, urea, high temperature (65 degrees C, 60 min or 80 degrees C, 30 min), mercaptoethanol and dithiothreitol were able to solubilize the zp but not the capsule at the concentrations used. Indirect immunofluorescence on cryostat sections and whole mounts of fresh or frozen-thawed material showed that 1) common antigens are shared by equine, porcine and bovine zp; 2) day 7 to day 15.5 capsule reacted with anti-capsule-serum but not with anti-zp-serum except for a few patches on the surface of the capsule; 3) anti-capsule-serum, but not anti-zp-serum, reacted with the capsular material recovered along with a broken day 27.5 conceptus; 4) anti-capsule-serum does not react with rabbit blastocyst coverings; 5) anti-capsule antibodies can be absorbed from the anti-capsule-serum by uterine proteins from either pregnant or non-pregnant mares; and 6) the capsule does not contain mouse laminin-like material.

Animals↗

PubMed1986

Experimental studies on the elongation of the ewe blastocyst.

After the zona is shed, the ewe blastocyst increases rapidly in diameter and length. The aim of the present study was to examine the control of trophoblast growth. Twelve-day old ovine blastocysts, cut into pieces and cultured in vitro for 24 h, gave rise to structures called trophoblastic vesicles (blastocysts without the embryonic disc). Such trophoblastic vesicles (TV), cultured at least 5 to 10 days or more in vitro, were able to survive. However, they did not increase in length and only some of them began to form small buds. In contrast, after they were transferred surgically into the uterine horn ipsilateral to the corpus luteum on Day 12 of the oestrous cycle, these TV were elongated in 5 out of 7 recipient ewes slaughtered on Day 17. The structure of the TV was observed by scanning electron microscopy before and after in vitro elongation and then compared with that of control blastocysts which had been cultured or not. This study demonstrates that trophoblast elongation does not depend necessarily on the presence of the embryo proper, but can occur in TV composed only of the trophectoderm and the extraembryonic endoderm. The results also suggest that some unknown uterine factor(s) is involved in the development of trophoblastic tissue.

Animals↗

PubMed1986

Endocytotic activity in the endometrium during conceptus attachment in the cow.

The uptake of horseradish peroxidase tracer injected into the uterine lumen of the cow was studied during the period of conceptus attachment (Days 18-21; Day 0 = oestrus) and also in cyclic animals. Endocytosis occurred in pregnant and non-pregnant cows but was especially marked when circulating progesterone concentrations were high. By 20 min after injection, the tracer was located in apical endocytotic vesicles and in organelles of the lysosomal system. In addition, some of the horseradish peroxidase-containing vesicles were associated with the lateral membranes of the cells and the tracer was also present in the intercellular spaces and beneath the basal membrane, especially in pregnant animals by the time of conceptus attachment. There was no evidence that pinopod-like functions could be attributed to large cytoplasmic protrusions from endometrial cells. Rather, the protrusions seemed to be involved in secretory processes. The presence of clear vesicles among the endocytotic vesicles suggested a coupled secretory-endocytotic activity of the cells, the significance of which remains to be determined.

Animals↗

PubMed1982

Ultrastructural features of the cell surfaces of uterine and trophoblastic epithelia during embryo attachment in the cow.

Ultrastructural features of the bovine uterine and trophoblastic epithelial cell surfaces were studied by scanning electron microscopy (SEM) at the time of attachment. Apical cytoplasmic protrusions were observed on the uterine cell surface from cyclic animals on days 12-16 during the luteal phase and disappeared thereafter. However, in pregnant animals, these cytoplasmic protrusions were observed until day 21 (attachment stage). These structures suggest that the uterine cells possess secretory and/or endocytotic properties. Before the attachment stage the trophoblastic cell surface was uniformly covered by slender microvilli. At the beginning of conceptus attachment the microvilli disappeared and the trophoblastic cell surface became smooth. On areas of the conceptus facing uterine gland openings, papillae developed and filled the glandular lumen. These were interpreted to be a system by which the conceptus is immobilized on the uterine epithelium and/or a histotrophic mechanism for absorbing glandular secretory products.

Animals↗

PubMed1982

Cytochemical studies of uterine and trophoblastic surface coats during blastocyst attachment in the ewe.

A glycoprotein coat was demonstrated on the outer surface of both the uterine and trophoblastic cells using ruthenium red, cationized ferritin, concanavalin A-peroxidase and phosphotungstic acid in HCl. No changes were observed on the uterine epithelial surface of cyclic or pregnant animals before or during blastocyst attachment (Day 15). However, the cytochemical reactions were different on the trophoblastic cells of blastocysts at Days 13 and 15, the ruthenium red and cationized ferritin sites of reaction and the concanavalin A receptors being more homogeneously distributed on the outer surface of Day-15 trophoblast. The phosphotungstic acid staining demonstrated a glycoprotein substance between the trophoblast and the uterine epithelium in adhesion areas by Day 18. The results suggest that biochemical changes occur in the composition or distribution of the trophoblastic cell coat during the process of blastocyst attachment in the ewe.

Animals↗

PubMedDate not supplied

Trophoblastic interferons: do they modulate uterine cellular markers at the time of conceptus attachment in the pig?

Between days 12 and 20 of pregnancy, the trophectoderm of the porcine conceptus secretes two species of interferons (IFN): IFN-gamma (Type II), which is produced in substantial amounts, and IFN-delta (type I), for which secretion peaks at days 15-16 of gestation. The role of these embryonic IFNs is not known. We made the assumption that, in the pig, one possible role of these IFNs may be the remodelling and/or depolarization of the uterine endometrial epithelium, as a prerequisite for implantation and establishment of a functional placenta. A comparative analysis by immunohistochemistry of several cell membrane markers and ECM components of the cyclic and pregnant uterus was performed at day 15 post-oestrus. The markers were those likely to differ between a pregnant and cyclic uterus, or between different stages of pregnancy. A highly specific marker of IFN-gamma activity, namely MHC class II antigens in the uterine mucosa, was also examined. This study provides so far unreported data: in the endometrial epithelium of the pregnant uterus, we observed a partial relocalization of ZO-1, a marker of epithelial tight junctions, thus suggesting significant changes to the endometrial polarity. Heparan-Sulphate Proteoglycan (HSPG) expression did not differ significantly between cyclic and pregnant uteri. In contrast with the accepted rodent model of trophoblast-uterus adhesion, the porcine trophoblast and luminal epithelium were negative for HSPG. Finally, MHC class II antigens were absent from the cyclic uterus, but markedly induced in the day 15 pregnant uterus, particularly in endothelial cells, suggesting that IFN-gamma may indeed cross the maternal epithelium. This hypothesis was supported by the observation of IFN-gamma immunoreactivity associated with clusters of endometrial cells in the pregnant uterus.

Animals↗

PubMedDate not supplied

Conceptus attachment in the ewe: an ultrastructural study.

Scanning and transmission electron microscopic observations were made on trophoblast, caruncles and intercaruncular areas during the attachment of the conceptus. Three stages were determined: 1. From day 14 on, precontact was established and the conceptus appeared to be immobilized in the uterine lumen. On the centres of the caruncles which were depressed and folded the epithelial cells developed bulbous cytoplasmic protrusions. Throughout the free life of the conceptus, the trophoblast cells showed an abundant covering of microvilli. 2. On day 15, apposition occurred: most microvilli on the surface of the trophoblast disappeared. 3. Between days 16 and 18, adhesion began as a result of the interpenetration of the uterine microvilli and cytoplasmic projections of the trophoblast cells. During that stage trophoblast giant cells appeared and the uterine epithelium was turned into syncytial masses; however, it was apparently not destroyed later on. Between the caruncles, the trophoblast developed finger-like villi which invaded the lumen of the uterine glands from days 15 to 18. During their short life-time (they vanish at day 20), these trophoblastic differentiations may anchor the pre-attachment conceptus and absorb the histotrophic secretions of the glands.

Animals↗

PubMedDate not supplied

Interferon-delta: the first member of a novel type I interferon family.

We have recently described a novel type I interferon (IFN) co-expressed with IFN-gamma by the trophectoderm of the pig conceptus between day 12 and day 18 of gestation, a development stage that corresponds to implantation in the uterus. This IFN, now officially named IFN-delta, is recognized as the first member of a novel type I IFN family. This paper reviews the main published data on IFN-delta, together with some new data, showing that IFN-delta, while being a true type I IFN, has some very specific structural and biological properties. Sequences related to IFN-delta coding sequence were found in the genome of man and other ungulates but the only other potentially functional gene was found, so far, in the horse. The pig IFN-delta mature protein, with 149 amino acids, is the smallest of all known type I IFNs. It is unusually rich in cysteines (seven residues), and has a very basic isoelectric point. Recombinant IFN-delta expressed in insect cells is glycosylated and has a high antiviral activity on porcine cells, but not on human cells. It has high antiproliferative activity, which is significantly enhanced in the presence of IFN-gamma. This new IFN was shown to bind on pig cells to the same type I receptor as IFN-alpha. IFN-delta and IFN-gamma genes are co-regulated in the pig trophectoderm, whose cells on day 14-16 of development simultaneously secrete both IFN proteins. The biological role of porcine IFN-delta in early pregnancy has been found unrelated to the known antiluteolytic effect of trophoblastic IFN-tau in ruminants.

Amino Acid Sequence↗