A new cytoplasmic component in the trophoblast cells of the rat and mouse

Abstract

Tissue blocks removed from placentas of rats and mice at different gestational age were fixed in either oso4 or glutaraldehyde or both, embedded into Araldite, and thin sections were examined with the electron microscope. A hitherto undescribed cytoplasmic component consisting of convoluted thread-like elements embedded in a clear ground substance has been regularly found in the trophoblast I I cells of rats and mice. The ovoid-shaped cytoplasmic component, termed by us gEomerular body, is about 1 to 1.5 JL in its greatest diameter and is composed of electrondense 400 to 500 A thick threads which appear to have a fine filamentous and granular structure. The threads were often observed in close topographical relationship with free ribosomes. The thread-like elements of the glomerular body were occasionally found dispersed or lined up under the cell membrane of the foctal side of the trophoblast I I cell. In some instances similar structures were observed in the nucleus. The nature and significance of the glomerular body is unknown.In the course of the electron microscopical investigation of the chorioallantoic placenta of rats and mice we found in the trophoblast cells a peculiar cytoplasmic component, which, to our knowledge, has not yet been described. Only one short note is known in the literature on the existence of a similar structure (Enders, '65). On the basis of its shape and convoluted structure it was termed by us "glomerular body."According to the observations of Enders ('65) the ultrastructure of the placenta in the mouse is very similar to that of the rat which has been described in detail by Jollie ('64). The latter author distinguishes four cellular layers separating the maternal blood sinus from the foetal capillary lumen: ( a ) trophoblast I; (b) trophoblast II; ( c ) element III and ( d ) endothelium. According to this terminology we found the glomerular bodies exclusively and characteristically in the trophoblast II,cells. They could first be recognized at the'thirteenth or fourteenth day of gestation, persisted throughout late pregnancy, and were found after birth. MATERIAL AND METHODSThe fine structure of the placenta in rats of increasing gestational age from the twelfth to the twenty-second day and in ANhT. REC., 155: 385-400.mice from the fifteenth and twentieth days post coitum, was observed in electron microgr aphs.Animals were anesthetized by intraperitoneal injection of Narcothion (Bthyl-(1-methyl-propy1)-thiobarbitur acidic sodium, "Sanabo" Wien). Tissue was taken from the superficial and deeper labyrinth near to the junctional zone from each placenta. The blocks were fixed for 1.5 hours in 1% OsO,, buffered to pH 7.4 with Millonig phosphate buffer at 4°C. Some of the placentas were fixed for 3 to 4 hours in 0.14 M or 0.08 M Na-cacodylate-buffered (pH 7.4) 6% glutaraldehyde at room temperature and postfixed as above in 0~0~. The tissue blocks were dehydrated in ethanol and embedded in Araldite. Thin sections were cut on a Porter-Blum and on an OMU-2 ultramicrotome, stained with...

Coiled bodies in supraoptic nuclei of the rat hypothalamus during the postnatal period

“…Several reports on CBs have pointed out the presence of nematosomea (n~icleolus-like bodies) in the cell cytoplasm (Toro and Rohlich, 1966;Grillo, 1970;Le Beux, 1971). Our results confirm the simultaneous occurrence of both structures, but it is difficult to ascertain their functional significance.…”

Cytoplasmic Inclusions Resembling Nucleoli in Sympathetic Neurons of Adult Rats

“…On the other hand, there is little doubt that the nematosomes bear a striking resemblance to the inclusions called "glomerular bodies" by Toro and Rohlich (57) in the syncytial trophoblast of the mouse and rat placenta . Apart from being substantially more numerous, the placental inclu-sions are somewhat larger than nematosomes, and they usually have a "granular" rather than ropelike appearance .…”

Nematosomes in the Rat Trigeminal Ganglion

“…Other situations in which bodies resembling nematosomes have been found are in a neuron of the cerebral hemisphere of the adult toad' and as structures designated "glomerular" bodies in the syncytial trophoblast of the mouse and rat placenta (14) .…”