Biomedical subjects

R Leiser

Publications and source records attributed to R Leiser.

At least 37 records · Page 2Linked to original sources

PubMed2001

Differential expression of two carbohydrate epitopes, CD15 and HNK-1, in developing vertebrate olfactory receptor neurones.

According to the view of differentiation-related alterations in the glycosylation pattern of neurones, recent studies have shown development dependent expression patterns of lactoseries carbohydrate epitopes, CD15 and HNK-1, on olfactory receptor neurones in rats and chicks. In order to evaluate a general role for these epitopes during development of vertebrate olfactory receptor neurones, this investigation focuses on the situation in the mouse, bovine and Xenopus olfactory epithelium. In all three species CD15 expression was found on a subpopulation of morphologically mature receptor cells starting at the time of initial synaptogenesis. Whereas for bovine and Xenopus the timetable of HNK-1 expression is similar to that described for the chick, suggesting involvement in pathfinding, in the mouse HNK-1 is found on immature cells when mature CD15 positive receptor cells could already be discerned. By our results a role for CD15 during establishment of synaptic contacts and for HNK-1 during their formation is suggested.

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

Canine relaxin-like factor: unique molecular structure and differential expression within reproductive tissues of the dog.

Employing postpubertal testicular tissue, we determined the cDNA coding sequence of a truncated canine relaxin-like factor (RLF) consisting of a signal peptide of 28 amino acids (aa), a B-domain of 23 aa, a truncated C-domain of 34 aa, and an A domain of 26 aa, respectively. Within the B-domain of canine RLF, the putative relaxin receptor binding motif contained a single substitution with the C-terminal arginine replaced by a serine residue, and the putative RLF receptor binding motif was truncated. Leydig cells specifically expressed RLF in the normal postpubertal and cryptochid testis as well as in testicular Leydig cell adenoma. The epididymis was an additional source of RLF in the dog. In the female reproductive tract, expression of immunoreactive RLF and relaxin were compared. Within the ovary, RLF, but not relaxin, was detected in follicular theca interna and granulosa cells and the corpus luteum. In the nonpregnant uterus, luminal and glandular epithelium coexpressed RLF and relaxin. Uteroplacental tissue at early stages of gestation revealed RLF expression in the proliferative fetal villous cytotrophoblast and in maternal uterine cells. In the mature canine placenta, the trophoblast surrounding the maternal blood vessels and the hemophagous cytotrophoblast of the paraplacental zone expressed RLF. Canine relaxin was absent in the paraplacental areas. Western analysis of placental tissue extracts revealed the presence of specific immunoreactive bands likely resembling unprocessed and enzymatically cleaved RLF. Differential expression of RLF and relaxin appears to reflect distinct autocrine and paracrine functions of RLF in canine reproductive tissues.

Amino Acid Sequence↗

PubMed2001

The blood vasculature as the forming element of the uterus of the estrous donkey (Equus asinus).

Light, scanning electron microscopy of endometrial surface and vascular casts were used to study the vascular architecture of the donkey uterus during estrous. The arterial blood supply of the uterus comes from three arteries: the uterine branch of the ovarian artery, the uterine artery of the external iliac artery, and the uterine branch of the urogenital artery. All arteries enter the uterus at its mesometrial border and divide into smaller ones. Segmentally constricted arteries are seen to circumscribe large veins at the perimetrium which become highly convoluted in the intermuscular vascular layer of the myometrium. Small arteries and arterioles originate at the borderline between the myometrium and the endometrium and radiate to the surface of the endometrium to constitute a system of numerous ridges and grooves by a widely meshed plexus of subepithelial capillary network. The post-capillary venules of the endometrium arise from the subepithelial capillary plexus to form slightly larger veins than the concurrent arteries which join up to the large tortuous veins in the intermuscular vascular layer of the uterus. This arrangement of blood vessels in the donkey uterus and particularly in the endometrium provides the requirement for instant blood flow on the arterial side and for the slow flow rate on the venous side to ameliorate the process of substances exchange.

Animals↗

PubMed2000

Heme oxygenase-2 and nitric oxide synthase immunoreactivity of bovine olfactory receptor neurons and a comparison with the distribution of NADPH-diaphorase staining.

It has recently been suggested that, in addition to nitric oxide (NO), carbon monoxide (CO) is an important gaseous messenger which might be involved in vertebrate olfactory transduction because its effects include activation of guanylyl cyclase and the formation of cGMP. As there is no information regarding the presence of heme oxygenase-2 -- the constitutive isoform of the heme oxygenase system -- in olfactory neurons of non-rodent species, we have investigated the distribution pattern of heme oxygenase-2 in the olfactory epithelium of the bovine, a representative of macrosmatics. Localization of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity of the olfactory epithelium was compared with heme oxygenase-2 and NO synthase (NOS) immunoreactivities in order to obtain possible hints at functional significance. NADPH-d activity was particularly intense in apical dendrites of receptor neurons. It was also found in Bowman glands and intraepithelial duct cells. Less intense, discrete NADPH-d activity was present also at intermediate and basal levels of the olfactory epithelium, corresponding to the layer of receptor neuron somata and basal cells. While heme oxygenase-2 activity mainly occurred in neuronal perikarya, a very intense NOS immunoreactivity, exclusively for the inducible isoform, was detected in the apical dendrites. Ultrastructurally, NADPH-d histochemistry showed distinct labelling of membranes, in particular of endoplasmic reticulum, mitochondria and nucleus. The coincident localization of the moderate NADPH-d activity and heme oxygenase-2 immunoreactivity in receptor cell perikarya suggest a functional association between NADPH-cytochrome P450 reductase and heme oxygenase-2. In contrast, dendritic localization of NADPH-d activity is topically and possibly functionally related to the presence of the inducible isoform of NOS. The results suggest that both CO and NO may be generated in bovine receptor neurons and thus involved in odorant stimulation. Based on immunocytochemical localization of synthesizing enzymes, NO might be regarded as a direct regulator of transduction related processes while CO might act as a modulator of the initial signal.

Animals↗

PubMed2000

Ruminant relaxin in the pregnant one-humped camel (Camelus dromedarius).

We have determined the cDNA sequence of preprorelaxin in the pregnant one-humped camel by employing reverse transcription- and rapid amplification of cDNA ends-polymerase chain reaction. Camel preprorelaxin consisted of 600 base pairs (bp) encoding a protein of 199 amino acids (aa) with a signal peptide of 25 aa (75 bp), a B domain of 28 aa (84 bp), a C domain of 121 aa (366 bp), and an A domain of 24 aa (72 bp). The N terminus of the C domain of camel prorelaxin contained the unique proline-rich repetitive sequence (-RPAP)(3)-(-K/RPAL-)(2), and within the B domain the classical -GRELVR- receptor binding motif was found. Camel preprorelaxin showed highest homology with porcine (74.6%) and equine (65.4%) relaxin. The ovary and the uteroplacental unit were a dual source of relaxin in the pregnant dromedary. Within the ovary, weak expression of relaxin was detected in large luteal cells of the mature corpus luteum. In the ovarian follicles, immunoreactive relaxin, but not relaxin mRNA, was detected in the granulosa and theca interna cell layer. Beginning at around Day 93 of gestation and coinciding with increasing interdigitation of the fetal villus with the underlying maternal endometrium, uterine luminal epithelial cells in the uteroplacental tissue expressed relaxin. Weak expression of immunoreactive relaxin, but not relaxin mRNA, was observed in villous trophoblast cells. Pseudostratified trophoblast cells at the base of the placental villi and multinucleate giant cells did not express relaxin.

Amino Acid Sequence↗

PubMed2000

Production of protein hormones by cultured trophoblast cells isolated from term and early placentae.

PROBLEM: To compare the capacity of de novo hormone synthesis by cultured trophoblast cells isolated from early and term placenta as cytotrophoblast, and to determine the ability of these cells to proliferate in culture. METHOD OF STUDY: Cytotrophoblast cells were isolated from term (TP, 38-42 weeks) and early placentae (EP, 8-13 weeks) by enzymatic digestion and subsequent purification on a percoll gradient. The net synthesis of the hormones human placental lactogen (hPL) and human chorionic gonadotropin (hCG) was determined as the release during culture + cell content after culture - cell content before culture. Proliferation was determined using a dedicated colorimetric reagent (CellTiter 96). RESULTS: Using a percoll gradient we were able to isolate three cell bands with densities of 1.051, 1.058, and 1.063 g/mL, which were predominantly cytotrophoblast cells as shown by immunocytochemical analysis. The cytotrophoblast cells with the highest density (1.063 g/mL) were used because they were found to release the highest amount of hormones and have shown the lowest rate of cell death after 6 days in culture. Both hCG and hPL showed different patterns of release during the first 2-3 days of culture between TP and EP. While the release by EP cytotrophoblast cells continued during 6 days of culture (n = 4), the concentrations for TP cytotrophoblast (n = 4) reached a plateau between 4 and 6 days. Net de novo synthesis calculated for 3 x 10(4) TP trophoblast cells cultured for 6 days (mean +/- SD, n = 4) was 8.65 +/- 9.05 mU for hCG and 0.95 +/- 0.45 ng for hPL. For EP, it was 395.5 +/- 265.5 mU for hCG and 148.8 +/- 84.2 ng for hPL. Net synthesis of hCG was > 10-fold (TP) and > 70-fold (EP) higher than the initial cell content. While at term, hPL synthesis was only a fraction of the initial cell content, production by EP cytotrophoblast was 106 times the initial cell content. The extent of cell death after 6 days in culture was significantly (P < 0.02) higher for term (30-40%) than for early trophoblast (10-20%). Using a proliferation detection agent during the first 3 days of culture with first trimester cytotrophoblast cells, we did not find any changes in the proliferative activity. CONCLUSIONS: There are differences in the functional activity between trophoblast cells obtained from first and third trimester. The in vitro findings are difficult to reconcile with the different patterns of plasma concentrations of the two hormones observed in vitro during the course of pregnancy.

Cells, Cultured↗

PubMed2000

Identification of central nervous system tissue in retail meat products.

A procedure to detect tissues from the central nervous system that involved quantification of cholesterol and immunochemical detection of neuron-specific enolase and glial fibrillary acidic protein was used to analyze 402 samples of heat-treated meat products from various food outlets in Germany. The cholesterol content of 16 samples (4.0%) indicated the possible presence of central nervous system tissue because the levels exceeded the normal maximum cholesterol content of cooked sausages. In 7 of these 16 heat-treated meat products, immunoblotting of both neuron-specific enolase and glial fibrillary acidic protein confirmed the presence of CNS tissue. Repeated sampling by veterinary officials and analysis by both cholesterol quantification and immunoblotting confirmed these findings. Whereas all of the control samples (with and without added central nervous system tissue) were correctly classified by both cholesterol quantification and immunoblotting, negative results of immunoblotting must be carefully interpreted in the case of intensively heat-treated meat products. Thus, studies have yet to establish an increase in sensitivity of immunoblotting of neuron-specific enolase and glial fibrillary acidic protein. However, the detection of illegal use of central nervous system tissue in heat-treated retail meat products demonstrates the need for suitable analytical methods to control transmissible encephalopathies and to enforce labeling laws.

Animals↗

PubMed2000

Glycosylation in the near-term epitheliochorial placenta of the horse, donkey and camel: a comparative study of interbreeding and non-interbreeding species.

Studies from this laboratory have shown great diversity in the glycosylation of tissues comprising the interhaemal barrier of species with different placental types. This diversity may be one of the factors preventing interbreeding between species. Glycan expression within the uterine epithelium and trophoblast of the interhaemal barrier was examined to test this proposition in three species with similar diffuse, microcotyledonary, epitheliochorial allantochorionic types of placenta: the horse (Equus caballus) and donkey (Equus asinus), which can interbreed with each other, and the camel (Camelus dromedarius), which cannot interbreed with either of the other two species. A panel of 14 lectins was used and it was found that glycosylation patterns were generally similar between placental tissues of the horse and donkey, except for the expression of non-bisected complex N-glycan and some sialic acids, whereas those of the camel showed striking differences in the binding of lectins to many structures carrying terminal residues of fucose, N-acetyl galactosamine and beta-galactose, as well as to complex N-glycans and sialic acids. These results are consistent with the proposition that interbreeding species carry similar glycans in tissues forming the interhaemal barrier whereas glycodiversity is one of the factors preventing implantation and subsequent placental development in interspecific hybrids.

Animals↗

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

A lectin binding analysis of glycosylation patterns during development of the equine placenta.

The glycosylation of the equine interhaemal barrier and areola was studied throughout the period of gestation. Placentae of 35, 37, 50, 119, 152, 200, 280 and 300 days gestation were investigated, using semithin plastic embedded sections and a panel of 15 biotinylated lectins with an avidin-peroxidase revealing system. Glycosylation of the trophoblast and maternal epithelium showed the most change during the first 50 days of gestation, being associated with the initial stages of adhesion and attachment. In the trophoblast, non-bisected tri/tetraantennary complex N-glycan was only evident after day 37 and terminal N-acetyl galactosamine, alpha2,3- and alpha2,6-linked sialic acids disappeared at the same time. The areolar trophoblast exhibited some differences from microcotyledonary areas, especially with respect to 2-deoxy, 2-acetamido alpha-galactose and tri/tetraantennary, non-bisected complex N-glycan, suggesting that the differences in function between microcotyledonary and areolar trophoblast are reflected at both the morphological and the biochemical level. Granules of the maternal uterine epithelium bound many lectins, particularly those with specificity for bisected and non-bisected bi/triantennary N-linked glycan, 2-deoxy, 2-acetamido alpha-galactosyl, beta-galactosyl and some fucosylated termini. Binding to sialic acids in alpha2,3- and alpha2,6-linkage was sparse. Maternal and fetal capillaries showed little change in glycan expression over the period studied, being rich in bisected and non-bisected bi/triantennary N-linked glycan and sialic acids, with some terminal N-acetyl galactosamine and no detectable terminal fucosyl residues.

Acetylgalactosamine↗

PubMed1999

Equine placental cup cells show glycan expression distinct from that of both chorionic girdle progenitor cells and early allantochorionic trophoblast of the placenta.

Using lectin histochemistry on plastic-embedded material, the glycosylation patterns of equine girdle and cup cells, and associated endometrial glands, have been investigated from 37 to 67 days gestation. Results were compared with the glycosylation of the 50-day allantochorionic trophoblast of the established equine placenta that will later form the microcotyledons. The differentiated cup cells, which secrete equine chorionic gonadotropin (eCG), showed a pattern of glycosylation that was distinct both from the progenitor girdle cells and the allantochorionic trophoblast, with granules that bound lectins indicating high levels of alpha2,6 and alpha2,3-linked sialic acid, N-acetyllactosamine and bi/tri antennary non-bisected and bisected complex N-glycan. This is consistent with the known carbohydrate content of eCG. In contrast, the allantochorionic trophoblast at 50 days lacked detectable amounts of sialic acid and showed high levels of tri/tetra-antennary non-bisected complex N-glycan and N-acetyl galactosamine which was absent in the cup cells. During the process of girdle cell migration into maternal tissues, the uterine glands became greatly enlarged and dilated basally, with increased amounts of glycosylated secretory products revealed by lectins, which often seeped out into the extracellular space via ruptures in the apical regions of the gland wall.

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

Development of an integrated procedure for the detection of central nervous tissue in meat products using cholesterol and neuron-specific enolase as markers.

The emergence of a new variant of Creutzfeldt-Jakob disease during the bovine spongiform encephalopathy epidemic has focused attention on the use of tissue from the central nervous system (CNS) in food. So far, the banning of CNS tissue could not be effectively controlled because procedures for detection were missing. With regard to preventive health protection and labeling law enforcement, we have developed an integrated procedure for the detection of CNS tissue in meat products. Herein, we show that antigenic characteristics of neuron-specific enolase (NSE) quantitatively survive technological treatment including severe homogenization and pressure heating. Using both poly- and monoclonal antibodies against NSE in the Western blot, bovine and porcine brain could be detected in sausages, albeit with varying sensitivity (1 to 4%). Sensitivity was increased after reduction of fat content (30 to 40%) of the samples by means of a soxhlet extraction. This made possible the detection of brain addition as low as 0.25% when using monoclonal antibodies. Immunohistology showed distribution of CNS tissue in heat-treated meat products to be homogeneous. Immunoreaction was not found to be bound to morphologically intact histological or cytological structures; however, it proved to be highly specific. The quantification of cholesterol provides a low-cost screening method for the rapid identification of meat products, suspicious with regard to CNS tissue addition. Cholesterol content increased by 26 mg per 100 g of fresh substance for each percentage of brain added to internally produced reference material. Using three different approaches (internal reference material, raw material, and field samples), a provisional cutoff point of normal cholesterol content was calculated for emulsion-type cooked sausages to be 115 mg/100 g (P < 0.05).

Animals↗