- Email: [email protected]
Vascularisation I mink placenta : A study based on scanning electronmicroscopy of corrosion casts combined with conventional light- and transmission electronmicroscopy
A.77
Abstracts" E P.G and R.T C Belgtum 1995
VASCUI-ARISATION I MINK PLACENTA : A STUDY BASED ON SCANNING ELECTRONMICROSCOPY OF CORROSION CASTS COMBINED WITH CONVENTIONAL LIGHT- AND TRANSMISSION ELECTRONMICROSCOPY. Winther H.a, Dantzer V. t, Krebs C) and Leiser R.2. 1Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, Copenhagen, Denmark and 2Institute of Veterinary Anatomy, Histology and Embryology, University og Giessen, Germany. Vascularization of placentae tissue is crucial in establishing a functional organ, responsible for the exchange of nutrients and waste products between mother and embryo/foetus. The mink has an incomplete zonary, labyrinthine, and endotheliochorial placenta. In addition the mink exhibits delayed implantation, with pregnancy lasting between 39 and 123 days (39 days + 84 days of delay). The numbers of embryos surviving being inversely related to the length of the delay in implantation. In this study near term mink placentae were either perfusion-fixed with glutaraldehyde for LM and TEM or peffused - through branches of the uterine or umbilical artery - with a liquid plastic for corrosion casts. Both conventional light microscopy and SEM of corrosion casts reveal a lobular structure of the placental labyrinth providing a three dimensional framework of vessels where maternal capillary sinusoids and fetal capillaries meet in a one-way cross-current arrangement. These architectural blood-flow conditions between maternal and fetal capillary systems are similar to the effectiveness of transplacental transport in the cat. LM and TEM reveal an interhemal distance at only 2 i.tm due to fetal capillaries indenting the syncytial trophoblast. Another characteristic phenomenon in the mink placenta are the high endothelial cells lining the maternal capillary sinusoids and the maternal stem vessels. SEM of corrosion casts illustrates an abrupt change m the endothelial pattern when maternal stem arteries from the myometrium enter the placenta labyrinth. TEM of these protuding endothelial cells reveal large cells with a well-developed rER, large Golgi-complexes, numerous mltochondna, large dark lipid droplets and an impressive cytoskeleton. Further investigations are needed to elucidate the function of these high endothelial cells. Supported by The Danish Agricultural and Veterinary Research Council.
NUCLEOLAR ORGANIZER REGION ACTIVITY TROPHOBLAST CELL P O P U L A T I O N S IN T H E PLACENTA T Z y b i n a l, E Zybma ~, E. Se~erova, Cytology RAS j and Institute of Experimental Medmine Russia
IN T H E MURINE A Dyban. RAMS, St
CAMBIAL A N D RAT Institute of Petersburg,
Nucleolar orgamzer region (NOR) activity in the junctional zone and labynnth trophoblast cells (TC) of the rat and murine placenta have been studied using silver staining of metaphase plates and mterphase nucleoli. C y t o p h o t o m e t r t c a l measurement of the DNA content m the mterphase nucle~ and mitotic figures showed that the camblal TC are both diploid and polyploid (2-64C), being capable of undergoing mitosis up to the octaploid level. At the earlier developmental stages (9th day of gestation m mice and 12th day in rats) up to 82% of diploid metaphases contained the highest posmble number of Ag-NORs (9-10 m m,ce and 5-6 m rats) At the later stages (10th day m mice and 13th day in rats) a significant decrease of the number of Ag-NORs has been observed, the majority of metaphases contained 3-8 Ag-NORs ,n mice (47,7%) and 3-6 Ag-NORs m rats (67,6%). The number and total area of nucleoh and Ag-stained nucleolar granules estimated usrng ~mage analyze system "Magiscan" did not show significant changes during the same developmental stages The data seem to reflect some peculiarities of rDNA transcnptmnal regulation during TC differentiation m the rodent placenta.
Abstracts" E P.G and R.T C Belgtum 1995
VASCUI-ARISATION I MINK PLACENTA : A STUDY BASED ON SCANNING ELECTRONMICROSCOPY OF CORROSION CASTS COMBINED WITH CONVENTIONAL LIGHT- AND TRANSMISSION ELECTRONMICROSCOPY. Winther H.a, Dantzer V. t, Krebs C) and Leiser R.2. 1Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, Copenhagen, Denmark and 2Institute of Veterinary Anatomy, Histology and Embryology, University og Giessen, Germany. Vascularization of placentae tissue is crucial in establishing a functional organ, responsible for the exchange of nutrients and waste products between mother and embryo/foetus. The mink has an incomplete zonary, labyrinthine, and endotheliochorial placenta. In addition the mink exhibits delayed implantation, with pregnancy lasting between 39 and 123 days (39 days + 84 days of delay). The numbers of embryos surviving being inversely related to the length of the delay in implantation. In this study near term mink placentae were either perfusion-fixed with glutaraldehyde for LM and TEM or peffused - through branches of the uterine or umbilical artery - with a liquid plastic for corrosion casts. Both conventional light microscopy and SEM of corrosion casts reveal a lobular structure of the placental labyrinth providing a three dimensional framework of vessels where maternal capillary sinusoids and fetal capillaries meet in a one-way cross-current arrangement. These architectural blood-flow conditions between maternal and fetal capillary systems are similar to the effectiveness of transplacental transport in the cat. LM and TEM reveal an interhemal distance at only 2 i.tm due to fetal capillaries indenting the syncytial trophoblast. Another characteristic phenomenon in the mink placenta are the high endothelial cells lining the maternal capillary sinusoids and the maternal stem vessels. SEM of corrosion casts illustrates an abrupt change m the endothelial pattern when maternal stem arteries from the myometrium enter the placenta labyrinth. TEM of these protuding endothelial cells reveal large cells with a well-developed rER, large Golgi-complexes, numerous mltochondna, large dark lipid droplets and an impressive cytoskeleton. Further investigations are needed to elucidate the function of these high endothelial cells. Supported by The Danish Agricultural and Veterinary Research Council.
NUCLEOLAR ORGANIZER REGION ACTIVITY TROPHOBLAST CELL P O P U L A T I O N S IN T H E PLACENTA T Z y b i n a l, E Zybma ~, E. Se~erova, Cytology RAS j and Institute of Experimental Medmine Russia
IN T H E MURINE A Dyban. RAMS, St
CAMBIAL A N D RAT Institute of Petersburg,
Nucleolar orgamzer region (NOR) activity in the junctional zone and labynnth trophoblast cells (TC) of the rat and murine placenta have been studied using silver staining of metaphase plates and mterphase nucleoli. C y t o p h o t o m e t r t c a l measurement of the DNA content m the mterphase nucle~ and mitotic figures showed that the camblal TC are both diploid and polyploid (2-64C), being capable of undergoing mitosis up to the octaploid level. At the earlier developmental stages (9th day of gestation m mice and 12th day in rats) up to 82% of diploid metaphases contained the highest posmble number of Ag-NORs (9-10 m m,ce and 5-6 m rats) At the later stages (10th day m mice and 13th day in rats) a significant decrease of the number of Ag-NORs has been observed, the majority of metaphases contained 3-8 Ag-NORs ,n mice (47,7%) and 3-6 Ag-NORs m rats (67,6%). The number and total area of nucleoh and Ag-stained nucleolar granules estimated usrng ~mage analyze system "Magiscan" did not show significant changes during the same developmental stages The data seem to reflect some peculiarities of rDNA transcnptmnal regulation during TC differentiation m the rodent placenta.