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C Pfarrer

Publications and source records attributed to C Pfarrer.

18 recordsLinked to original sources
PubMed2006

VEGF system expression in different stages of estrous cycle in the corpus luteum of non-treated and superovulated water buffalo.

Water buffaloes are easily adaptable animals, whose raising and economical exploitation have been growing in the last three decades all over the world. Hyperstimulation of ovarian function in this species is a common technique aiming to improve reproductive performance. Superovulatory treatment affects corpus luteum (CL) function, which is highly correlated to angiogenic process. The aim of this study was therefore to assess the temporal protein and mRNA expression of VEGF and its receptors in the CL of non-treated and superovulated buffaloes. For that purpose blood samples and CL from 36 healthy (30 untreated, groups 1-5, and 6 superovulated, group 6) non-pregnant buffaloes were collected and the samples were divided into 6 groups according to the age of CL. Plasma samples were submitted to RIA to measure progesterone concentration and CL were subjected to immunohistochemistry and real time PCR for VEGF (vascular endothelial growth factor), Flt-1 (fms-like tyrosine kinase receptor 1) and KDR (kinase insert domain containing region). The VEGF system protein and mRNA expression during CL life span of untreated animals showed a specific time-dependent profile, although protein did not always reflect mRNA concentrations. VEGF expression in luteal cells was high correlated to plasma progesterone levels. Superovulated CL showed a significant increase of the VEGF-system protein and a significant decrease of mRNA expression compared to untreated animals in the same stage of the oestrous cycle. We conclude that VEGF, Flt-1 and KDR protein and mRNA expression in buffalo CL is dependent of estrous cycle stage and superovulatory treatment is able to increase the translation rate of this system.

Animals↗
PubMed2006

Culture of mature trophoblastic giant cells from bovine placentomes.

The mostly binucleate trophoblast giant cells (TGC) found in bovine placentomes, in addition to synthesizing and releasing hormones play an important role in fetal development and maternal adaptation to pregnancy. Placentomes from early gestation were collected, and for isolation of mature TGC, three cellular disaggregation methods, mechanical (MECH), enzymatic by trypsin (TRYP) or collagenase (COLL) were compared to each other. Further on, the cell survival in culture medium (DMEM) supplemented with either 10% fetal calf serum (FCS) or 10% serum replacement (SR) on culture plates free of any substrate was evaluated over a period of 90 days by trypan blue exclusion. The cells were further characterized by HOECHST 33342 nuclear staining, and immunocytochemical staining with monoclonal antibodies against vimentin and cytokeratin. A mean total rate of TGC survival of 82.56% was recorded. Statistical analysis showed significantly higher survival rates after enzymatic disaggregation with COLL (86.23%) than following MECH (80.38%) or TRYP (80.91%) treatment. Supplementation of DMEM with FCS resulted in significantly higher cellular survival rates (87.13%) when compared to the addition of SR (77.73%). Analysis of the influence of both, disaggregation method and medium supplementation on TGC survival revealed statistically significant differences between the following groups: MECH-SR (71.09%) was significantly lower than all other groups; TRYP-SR (78.03%) was significantly different from all other groups; TRYP-FCS (83.43%) and COLL-SR (84.08%) were significantly lower than MECH-FCS (89.98%) which together with COLL-FCS (88.25%) showed the highest cellular survival rate. In summary, our results show that TGC isolated from early gestation placentomes may be viable for more than 90 days of culture. However, whether these TGC produce placental lactogen throughout this period has yet to be determined.

Animals↗
PubMed2005

Fibroblast growth factor (FGF)-1, FGF2, FGF7 and FGF receptors are uniformly expressed in trophoblast giant cells during restricted trophoblast invasion in cows.

The bovine placenta is characterized by a limited invasion of trophoblast giant cells (TGC). In contrast to mononuclear trophoblast cells (MTC), TGC are non-polarized cells, which migrate and fuse with single uterine epithelial cells throughout gestation. Fibroblast growth factors (FGF) were shown to be associated with the migratory activity of cells, cell differentiation and angiogenesis, and due to its localization in trophoblast cells were proposed as important regulating factors in hemochorial placentae of rodents and humans, and the (syn)epitheliochorial placenta of pig and sheep. Since migrating bovine TGC are of epithelial origin, but exhibit similarities to mesenchymal cells we hypothesize that the restricted trophoblast invasion in cattle is characterized by a specific FGF expression pattern. Therefore, the spatiotemporal expression of specific FGF factor:receptor pairs, either acting on cells of mesenchymal origin or on epithelial cells was examined in bovine placental tissues throughout gestation and prepartum by immunohistochemistry, semiquantitative RT-PCR and in situ hybridization. FGF1 protein was found in trophoblast, caruncular epithelium (CE) and stroma (CS), stroma of chorionic villi (SCV), and in fetal and maternal blood vessels. FGF2 signals dominated in maternal vascular endothelia (VE), immature TGC, and MTC, whereas staining in other cell types was clearly weaker. FGF7 protein was detected in fetal and maternal blood vessel as well as in immature TGC and MTC predominantly at the chorionic plate. FGFR immunoreaction was localized in immature TGC, MTC, and to a clearly lesser extent in CS, CE and fetal and maternal blood vessels. Mature TGC stained negatively for all examined factors and FGFR. The corresponding mRNAs specific for FGF1, -2, -7, total FGFR, and FGFR2 isoforms IIIb and IIIc were colocalized in immature TGC, whereas hybridization was substantially lower in CE and absent in CS, SCV and mature TGC throughout gestation, but switched to CS and VE immediately prepartum. Semiquantitative RT-PCR revealed higher mRNA levels for FGF1, FGFR, and FGFR2IIIc in cotyledons compared to caruncles (p<0.05), whereas it was the opposite with FGF2 (p<0.001). FGF7 and FGFR2IIIb mRNA levels did not differ between caruncles and cotyledons. Significant changes (p<0.05) of mRNA levels related to gestational age were found for FGF1 and FGFR2IIIc, but not for FGF2, -7, total FGFR, and FGFR2IIIb. The specific localization of all examined FGF family members in TGC suggests that TGC, apart from their classical function as producers of hormonal products, play other important roles in the regulation of bovine placentomal growth, differentiation and angiogenesis.

Animals↗
PubMed2004

Cytoskeletal filaments and associated proteins during restricted trophoblast invasion in bovine placentomes: light and transmission electron microscopy and RT-PCR.

Trophoblast cell migration is unusual in epitheliochorial placentae but occurs in placentomes of cows as "restricted" trophoblast invasion of binucleated trophoblast giant cells (TGC). Migration may be induced by integrin binding to the extracellular matrix initiating two pathways: (1) conformational changes of the actin cytoskeleton induced by an accumulation of its associated proteins and (2) integrin-dependent phosphorylation of various protein kinases. In cow placentomes, actin, its associated proteins (alpha-actinin, vinculin) and a key protein kinase of the signal transduction cascade (phosphorylated mitogen-activated protein kinase, pMAPK) were localized by immunogold-silver enhancement and immunoperoxidase staining at the light- and transmission electron-microscopical levels. Findings were confirmed by amplification of specific mRNA transcripts by reverse transcriptase/polymerase chain reaction. Actin and alpha-actinin were co-localized apically in mononuclear trophoblast cells, along the cytoplasmic membrane of TGC and apically in maternal crypt cells. The actin and alpha-actinin immunoreaction occurred as a band of electron-dense particles beneath the cytoplasmic membrane. Vinculin labelling was membrane-associated in TGC and in fetal and maternal endothelial cells. MAPK was observed as nuclear clusters in both kinds of trophoblast cells and was less dense in single uterine epithelial cells. Most MAPK immunoreactivity was detected in the nuclei of the trophoblast epithelium but was also sometimes membrane-associated in the cytoplasm. Thus, actin, alpha-actinin, MAPK and vinculin may be involved in the regulation of TGC migration. "Restricted" trophoblast invasion could serve as a model for invasive processes.

Actins↗
PubMed2004

Modulation of connexin expression in sheep endometrium in response to pregnancy.

The expression pattern of two typical gap junction channel proteins, connexin 43 and connexin 26 (Cx43 and Cx26), was identified in the endometrium of sheep, a species with epitheliochorial type of implantation, by indirect immunohistochemistry during the cyclic phases, early and late pregnancy, and immediately after birth. The extent of Cx43 immunoreaction bound to endometrial stromal cells of the early implantation stage (day 15 p.c.) was comparable to the situation observed in oestrus. The subsequent intensification of feto-maternal contact correlated with a striking increase of stromal Cx43 in the intercaruncular and caruncular regions of the uterus (days 18 and 21 p.c.) and the induction of Cx26 in the glandular epithelium of late implantation (day 21 p.c.). In contrast, both gap junction proteins, coexpressed in the stroma of placentomes and interplacentomal sections on days 131 and 145 p.c., decreased during late pregnancy, while an intense and augmenting staining for Cx26 was detected at the cell borders of the glandular and luminal epithelium. The spatial and temporal distribution of both connexins suggests that, under embryonal and hormonal influences, gap junctional communication is involved in the implantation process and the regulation of endometrial tissue functions during sheep pregnancy and indicates further, that this connexin expression path resembles more the invasive type of implantation.

Animals↗
PubMed2003

Interaction of integrin receptors with extracellular matrix is involved in trophoblast giant cell migration in bovine placentomes.

Integrins are heterodimeric glycoproteins involved in cell-cell and cell-extracellular matrix adhesion and signal transduction. We evaluated the distribution and the putative role of integrin receptors and extracellular matrix (ECM) proteins during trophoblast giant cell (TGC) migration and fusion with uterine epithelial cells in the cow. Placentomes from 24 cows, covering day 80 to day 270 of gestation, were used for indirect immunohistochemistry against integrin subunits alpha(1), alpha(2), alpha(3), alpha(4), alpha(5), alpha(6), alpha(v), beta(1), beta(3), beta(4)and ECM proteins collagen type I and IV, fibronectin, laminin. The basement membranes of fetal and maternal epithelia and endothelia were immunoreactive for laminin, fibronectin and collagen IV. Collagens I and IV were found in maternal stroma, while fibronectin was present in fetal and maternal stroma. The integrin subunits alpha(2), alpha(6)and beta(1)were observed in basal aspects of fetal and maternal epithelial and endothelial cells. Additionally, the alpha(6)and beta(1)integrin subunits were colocalized with laminin on TGC. The integrin alpha(2)subunit was also found on TGC, but localized with a strong gradient to the basal side. Cells of the maternal connective tissue, including endothelium, expressed alpha(1), alpha(2), alpha(3), alpha(5), alpha(6), alpha(v), beta(3)and beta(4). The expression of alpha(2), alpha(5), alpha(v), beta(3)and beta(4) occurred mainly in the septal tips. Cells of the fetal mesenchyme were positive for integrin subunits alpha(1), alpha(2), alpha(3), alpha(4), alpha(5), alpha(6), and beta(1). Our results indicate that alpha(2)beta(1)collagen and alpha(6)beta(1)laminin receptors anchor epi- and endothelial cells to basement membranes. We suggest that TGC migrate along a matrix of laminin and maintain cell-cell contact with mononuclear trophoblast cells via alpha(2)beta(1)heterodimers. Integrins in maternal stroma and fetal mesenchyme may be involved in the regulation of proliferation and differentiation of maternal septa and fetal villi.

Animals↗
PubMed2001

The three-dimensional feto-maternal vascular interrelationship during early bovine placental development: a scanning electron microscopical study.

Both the fetal and maternal microvasculature of bovine placentomes was examined by scanning electron microscopy of vascular casts. So far the development of the vascular architecture of the bovine placentome in early gestation has only been studied 2-dimensionally due to technical difficulties arising from the fragility of the early placental blood vessels. Repeated experiments led to the selection of the microvascular corrosion casts presented here. The vasculature of the maternal compartment is supplied by large caruncular stalk or spiral arteries, which release short maternal stem arteries. In the 3rd month of gestation, these arteries branch into several arterioles at their base, thus providing the vascular framework for the lower part of the septal walls of the primary crypts. In the 4th month, due to progressive longitudinal growth of the stem arteries, branching into arterioles occurs not only at the base, but over the whole length of the stem arteries. These arterioles supply the capillary complexes of the septa which resemble the major part of the septal vasculature and face the secondary crypts. Further indentation results in the formation of tertiary crypt capillary complexes, encircling the earlier secondary unit. From the 6th month of gestation the architecture resembles the fully developed maternal placenta with stem arteries running directly to the fetal side to branch into 4 to 6 arterioles, which turn back to enter secondary and tertiary septa. Maternal venules, collecting the blood from the capillary bed of secondary and tertiary septa, converge onto stem veins leaving the caruncle via branches of the uterine vein. The fetal part of the placentome is supplied by the cotyledonary arteries, which branch into fetal stem arteries that are the tributary to single villous trees. Over their whole course towards the maternal side, these give off arterioles entering secondary villi. The tertiary or terminal villous vasculature consists of capillaries, which are organised in serial capillary loops. This system is progressively elaborated in the course of gestation. In the 4th month there are only finger-like loops, whereas from the 6th month large fan-like structures can be observed. In early gestation the maternal and fetal blood vessels meet predominantly in a countercurrent fashion, changing to the less efficient crosscurrent exchange when the tertiary unit develops. These results indicate the development of a highly elaborated fetomaternal villous-crypt exchange system, already established in the 1st half of gestation, thus meeting the increasing needs of the fetus.

Animals↗
PubMed2001

Butyric acid stimulates rumen mucosa development in the calf mainly by a reduction of apoptosis.

In ruminants the stimulation of papillar growth by butyric acid is well described but effects on mitosis and apoptosis are not known. To clarify the effect of short chain fatty acids three groups of three calves received a basic ration of 100 g hay per day for 6 weeks and additionally milk replacer. From these, two groups were fed with increasing amounts of the salts of either propionic acid (53 to 390 g) or butyric acid up to (54 to 326 g). The control group instead received an additional isocaloric amount of milk replacer. Mitosis was characterized by Ki67 immunoreactivity, apoptosis by a modified TUNEL assay and by electron microscopy. The feeding regimes led to significant differences of papillar length, increasing from 1.0 mm (controls) to 2.2 mm (propionic acid) and 4 mm (butyric acid). This enlargement was partly explained by an increased mitotic rate for the two fatty acid groups. The difference between the fatty acid groups was mainly explained by different apoptotic rates which were only one third for butyric acid compared to propionic acid (P < 0.001). In conclusion, butyric acid is a specific inhibitor of ruminal apoptosis in vivo.

Animal Feed↗
PubMed2001

Muc-1, integrin, and osteopontin expression during the implantation cascade in sheep.

The extracellular matrix protein osteopontin (OPN) is a component of histotroph that increases in uterine flushings from pregnant ewes during the peri-implantation period and is localized on the apical surfaces of the uterine luminal epithelium (LE) and conceptus trophectoderm (Tr). The potential involvement of OPN in the implantation adhesion cascade in sheep was investigated by examining temporal, spatial, and potential functional relationships between OPN, Muc-1, and integrin subunits during the estrous cycle and early pregnancy. Immunoreactive Muc-1 was highly expressed at the apical surfaces of uterine luminal (LE) and glandular epithelium (GE) in both cycling and pregnant ewes but was decreased dramatically on LE by Day 9 and was nearly undetectable by Day 17 of pregnancy when intimate contact between LE and Tr begins. In contrast, integrin subunits alpha(v), alpha(4), alpha(5), beta(1), beta(3), and beta(5) were constitutively expressed on conceptus Tr and at the apical surface of uterine LE and GE in both cyclic and early pregnant ewes. The apical expression of these subunits could contribute to the apical assembly of several OPN receptors including the alpha(v)beta(3), alpha(v)beta(1), alpha(v)beta(5), alpha(4)beta(1), and alpha(5)beta(1) heterodimers on endometrial LE and GE, and conceptus Tr in sheep. Functional analysis of potential OPN interactions with conceptus and endometrial integrins was performed on LE and Tr cells in vitro using beads coated with OPN, poly-L-lysine, or recombinant OPN in which the Arg-Gly-Asp sequence was replaced with RGE or RAD. Transmembrane accumulation of talin or alpha-actinin at the apical surface of uterine LE and conceptus Tr cells in contact with OPN-coated beads revealed functional integrin activation and cytoskeletal reorganization in response to OPN binding. These results provide a physiological framework for the role of OPN, a potential mediator of implantation in sheep, as a bridge between integrin heterodimers expressed by Tr and uterine LE responsible for adhesion for initial conceptus attachment.

Actinin↗
PubMed1999

Adaptive angiogenesis in placentas of heavy smokers.

Smoking in pregnancy increases perinatal morbidity and mortality, suggesting impaired placental function, though placental weight is increased. We used scanning electron microscopy to show adaptive angiogenesis in term placental villi from smokers (n=4) and non-smokers (n=4). These images may aid communication of the dangers of smoking in pregnancy.

Adaptation, Physiological↗
PubMed1999

The development of the endotheliochorial mink placenta: light microscopy and scanning electron microscopical morphometry of maternal vascular casts.

The development of the mink endotheliochorial placenta has been studied by means of light microscopy and scanning electron microscopy of maternal vascular corrosion casts. The placental blood vessels of three groups of mink, representing early, intermediate and near-term gestational ages were either perfusion fixed for histology, or instilled with liquid plastic in order to prepare vascular casts, which were examined qualitatively and/or quantitatively. The maternal component of the placental vascular system evolves from preimplantation blood vessels between the endometrial glands, into which the initial feto-maternal contact is made. The influence of highly invasive syncytiotrophoblast provokes a transition of the maternal capillaries into extensively anastomosing sinusoids with a subsequent modification of their endothelial cells into large cells with luminal protrusions. Three-dimensionally, the sinusoids are arranged as vascular crypts. This implies a villous-crypt type of interdigitation for the mink, but since the fetal capillaries surround the maternal sinusoids as a dense network a labyrinth is formed. The vascular crypts are supplied by very short arterioles, branching from maternal stem arteries, which arise from branches of the uterine artery and move straight to the surface of the endometrium. Venous outlets of the sinusoids converge onto venules and large stem veins in the deepest portion of the endometrium. This architectural pattern persists until term. Morphometry was used to confirm the qualitative observations in vascular casts. The diameter of maternal vascular crypts significantly increased from 137.3+/-21.9 microm in early gestation up to 217.8+/-80.9 microm in the intermediate stage and 431.8+/-119.5 microm near-term, when compared to the paraplacental zone in early gestation (82.2+/-19.5 microm). The capillary or sinusoidal diameter also increased significantly from intermediate stage (42.9+/-11.8 microm) to near term (60.1+/-16.7 microm), whereas the difference in the paraplacental zone (7.3+/-2.1 microm) and early gestation (13.0+/-3.2 microm) was not statistically significant.

Animals↗
PubMed1999

Tripolar acytokinetic mitosis and formation of feto-maternal syncytia in the bovine placentome: different modes of the generation of multinuclear cells.

The vast majority of trophoblast giant cells in the ruminant placenta are binuclear and are believed to derive from mononuclear trophoblastic cells by a single acytokinetic mitosis. There is no satisfactory explanation for the generation of the small proportion of trophoblast giant cells with one, three, or more nuclei. In this light-and electronmicroscopic study of bovine placentomal tissue from the second half of gestation, developmental stages of the trophoblast giant cells are investigated. Large mitotic figures indicate mitotic polyploidization, which is proposed to be due to two subsequent acytokinetic mitoses. Tripolar mitoses offer an explanation for the development of trinucleate trophoblast giant cells. Measurements of nuclear volumes in a series of semithin sections revealed that three size classes of trophoblast giant cells occur. The approximately doubling of nuclear volume between each class is thought to reflect different levels of DNA content that result from polyploidization in this cell type. Although trinuclear feto-maternal hybrid cells are the standard outcome of the fusion of binuclear trophoblast giant cells with uterine epithelial cells, some syncytia with at least five nuclei were observed in the uterine epithelium.

Animals↗
PubMed1999

Localization of micro- and intermediate filaments in non-pregnant uterus and placenta of the mink suggests involvement of maternal endothelial cells and periendothelial cells in blood flow regulation.

Maternal stem arteries and arterioles of the endotheliochorial mink placenta have been shown to lack smooth muscle cells, suggesting a muscle-free attenuation of the maternal arterial pulse wave of the placenta. Since the endotheliochorial type of placenta by definition does not contain any maternal supportive tissue (e.g. connective tissue), except for the specialized interstitial layer, the aim of this study was to reveal cytoskeletal components able to compensate for the lack of conventional regulatory mechanisms of maternal placental blood flow. The study was undertaken on buffered formalin fixed tissues from 19 minks by immunohistochemistry and transmission electron microscopy to localize three major cytoskeletal filaments (desmin, vimentin and alpha-smooth muscle actin (alpha-sm-actin)) in non-pregnant uteri and placenta. The contractile alpha-sm-actin was immunodetected in the maternal subepithelial and periglandular connective tissue cells of the cyclic endometrium and during early gestation. During the transition from early- to mid gestation, maternal periendothelial cells appeared and showed alpha-sm-actin immuno-positivity; however, in late gestation, this activity could not be detected because the periendothelial cells had disappeared. Fetal endothelial cells displayed intense alpha-sm-actin immunoreactivity, which was in contrast to the alpha-sm-actin negative maternal endothelial cells. Allantochorionic mesenchymal cells also exhibited intense alpha-sm-actin immunostaining. Vimentin was immunohistochemically expressed in endothelial cells (maternal as well as fetal), maternal periendothelial cells, allantochorionic mesenchymal cells, and maternal connective tissue cells from early gestation. Desmin was not immunohistochemically detectable in cyclic endometrium and placental tissues. Transmission electron microscopy revealed the periendothelial cells to be enclosed by a thin interstitial layer. Additionally, the maternal endothelial cells displayed actin myofilament-like structures anchored basally. From our data we conclude that maternal periendothelial cells, immunoreactive for contractile actin, and maternal endothelial cells, possessing actin myofilament-like ultrastructures, act as supportive systems in the maternal vessel walls, probably influencing the regulation of the maternal blood flow.

Animals↗
PubMed1999

Immunolocalization of progesterone receptors in bovine placentomes throughout mid and late gestation and at parturition.

The corpus luteum is the main source of progesterone (P(4)) responsible for maintenance of gestation in cattle. So far it has not been possible to assign any biological role to placental P(4), which contributes only marginally and temporarily to peripheral maternal blood levels. In order to identify possible P(4) target cells within the placenta, placentomes from 150-, 220-, 240-, and 270-day-pregnant cows and from parturient cows (3 animals per group) were screened immunohistochemically for expression of the progesterone receptor (PR). During gestation, PR-positive staining was found exclusively in the nuclei of caruncular stromal cells (CSC; maternal part of the placentome) and of caruncular vascular pericytes. In placentomes from parturient cows, occasional positive nuclear staining was also observed in the walls of small caruncular arteries. The percentage of PR-positive CSC increased slightly from 51.8 +/- 2.6% on Day 150 to 56.2 +/- 5.6% at Day 270 (p < 0.05) and was 58.9 +/- 1.8% at parturition. These results suggest that in pregnant cattle, CSC are under the control of P(4) of placental rather than luteal origin. Thus, whereas luteal P(4) may regulate "coarse" systemic progestational functions in the maternal compartment in the classical hormonal manner, placental P(4) may act as a paracrine factor involved in the local regulation of caruncular growth, differentiation, and functions.

Animals↗
PubMed1999

Fetomaternal attachment and anchorage in the early diffuse epitheliochorial placenta of the camel (Camelus dromedarius). Light, transmission, and scanning electron microscopic study.

Placentae of 22 one-humped camel concepti with crown-rump lengths (CRL) ranging from 2.5 to 26 cm were studied. The placentae were processed for light, transmission and scanning electron microscopy of exposed surfaces and microvascular corrosion casts. In very early stages of pregnancy (2.5-4.5 cm CRL) three froms of fetomaternal interrelationship are described. (1) Precontact, where the mononuclear trophoblast cells are still separated from the uterine epithelium by a gap containing interareolar histotroph. Both fetal and maternal epithelia develop apical ectoplasmic pads in this location. (2) Apposition, where microvilli of the apical cell membrane of the trophoblast contact the uterine epithelium focally. Multinuclear trophoblast giant cells develop beside the population of already present mononuclear trophoblast cells. Uterine ectoplasmic pads can be observed. (3) Adhesion occurs when apical cell membranes of fetal and maternal epithelia adhere to each other closely, thus forming a 'normal' intercellular space of 20 nm width, without any intervening uterine luminal space. Microvillous interdigitation in this location varies from a non-microvillous 'smooth adhesion', to a distinctly villiform 'rough adhesion', and a 'semismooth adhesion' is achieved when trophoblastic microvilli make intimate contact with the non-microvillous uterine apical cell membranes of ectoplasmic pads. This fetomaternal attachment process is sufficient until the conceptus reaches approximately 9 cm CRL. Then, from 10 to 13 cm CRL, additional anchorage of the placenta to the endometrium is accomplished by the growth of temporary grooves and ridges of the allantochorion and the endometrium, which indent each other in a complementary fashion. The height of these groove-ridge structures increases gradually in 14 to 18 cm CRL fetuses, and they also widen at about 25 cm CRL, thus forming globular fetal troughs and irregular, thick maternal ridges. These together create units responsible for improved fetomaternal anchorage and metabolic exchange for the increasing needs of the growing fetus.

Animals↗
PubMed1999

[Computer-based image analysis for experimental and clinical morphology--principles, utilization and marginal limits].

The new computer based image analysis techniques are powerful tools for mophometrical and quantitative image analysis in case of clinical and experimental morphology. Digital image analysis requires a distinction between two phases 1. generation of fundamental data (x,y coordinates and grey values of the pixel) and 2. calculation of parameters from these data. Stereological procedures are very powerful in quantifying morphological phenomenons, but computer based image analysing techniques allow multiple analysis of morphological objects and analysis of statistical distributions. There is great scientific benefit using modern computer based image analysing techniques.

Animals↗
PubMedDate not supplied

DNA content and ploidy level of bovine placentomal trophoblast giant cells.

Cytophotometric measurement of the DNA content of Feulgen-stained nuclei in touch preparations of bovine placentomes (n =5) revealed that 8C nuclei occurred in all, 16C nuclei in two, and 32C nuclei in one specimen. The determination of ploidy level by in situ hybridization with a Y-chromosome specific DNA probe showed that the majority of the fetal nuclei in touch preparations of placentomes from male fetuses (n =5) are tetraploid. Generally two tetraploid nuclei lie close together. These findings indicate that polyploidization is a normal feature in the development of the mostly binucleate trophoblast giant cells (TGCs). A new model for the development of these cells is proposed: a primary acytokinetic mitosis leads to a binucleate cell with two diploid nuclei. This cell enters a second acytokinetic mitosis during which the chromosomes of both nuclei form a common metaphase plate. The resulting cell with two tetraploid nuclei undergoes an additional S-phase but does not enter a renewed mitosis. The functional significance of this genome multiplication may be an increased synthetic capacity of bovine TGCs, caused by an increased number of gene copies available for transcription. Since genome multiplication is a property of invasive trophoblast cells of different species, it may be advantageous for trophoblast invasion.

Animals↗