Placental function in two distantly related marsupials.

The biochemical composition of uterine and fetal fluids during pregnancy of the grey short-tailed opossum was compared with new and published data on the tammar wallaby. In the grey short-tailed opossum, there are three main phases of embryonic nourishment. During the first phase, the embryo obtains nutrients from uterine secretion transferred into the yolk sac. The amount of uterine secretion declines during the second phase up to the time of shell coat rupture. As a result, the protein concentration in yolk sac fluid also declines. During phase three, which begins with shell coat rupture, nutrients are predominantly available from the maternal blood. In the grey short-tailed opossum that lacks a vesicular, fluid-filled allantois, waste products such as urea are apparently stored in the yolk sac and from there pass into the maternal circulation across the invasive yolk sac placenta. In contrast, in the tammar wallaby, the main source of nutrients available to the late term fetus is glandular secretion that is complemented by substances from the maternal circulation via the chorio-vitelline placenta, and waste products are stored in the large, fluid-filled allantois.

Postpartum erythrophagocytosis, iron storage and iron secretion in the endometrium of the tree shrew (Tupaia) during pregnancy.

Tree shrews (Tupaia belangeri) develop a bidiscoid endotheliochorial placenta. In addition, histiotrophe secreted by uterine glands is absorbed by the paraplacental trophoblast. Histiotrophe which is rich in iron is necessary for erythropoiesis in the young embryo. This report is part of a study of the accumulation and metabolism of iron in the endometrium of precisely dated pregnant Tupaia belangeri by application of electron spectroscopy and histochemistry. In the endometrium of tree shrews which had been pregnant at least once, iron-laden granules were present in macrophages and secreting cells of uterine glands. Iron accumulated in the endometrium shortly after parturition, when macrophages phagocytosed erythrocytes at small haematomas 0.2-0.5 mm in diameter. These haematomas arose during parturition after bleeding into the uterine stroma when the placental discs were detached. At 24 h after parturition the following structural consequences of the erythrolysosomal breakdown of phagocytosed erythrocytes could be observed: free cytosolic siderin granules, membrane-bound siderosomes, telolysosomes (some of which contained myelin figures or lipid droplets) and mixed telolysosomes (containing membranous stacks and siderin granules). During the lysosomal degradation of phagocytosed erythrocytes, iron was transferred from haemoglobin into a different macromolecular compound. Electron energy loss spectra detected from inside siderosomes indicated an iron-oxygen compound, and high-power bright field electron micrographs of siderosomes demonstrated the ultrastructural pattern characteristic of ferritin. At about d 12 of a new pregnancy, macrophages containing siderosomes closely approached the bases of secreting cells of endometrial glands. This strongly suggests that iron is transferred from the macrophages to the glandular cells. Within the glandular cells, iron-rich histiotrophe was synthesised and released into the glandular lumen. Within the uterine cavity this histiotrophe was absorbed by the omphalopleure. We suggest that among eutherians, postpartum erythrophagocytosis, the transfer of iron from macrophages to uterine glands, and the paraplacental uptake of iron, represent an ancestral mechanism of iron supply to the embryo.

The monoptychic glands of the jugulo-sternal scent gland field of Tupaia: a TEM and SEM study.

The monoptychic 'apocrine' scent glands of the sternal region of two adult male Tupaia belangeri were studied by transmission and scanning electron microscopy, in order to assess the modes of release of their secretory products. In segments of the secretory tubules with a narrow lumen the epithelial cells are columnar and are firmly connected to each other by desmosomes and junctional complexes. Myoepithelial cells are interspersed between the secretory epithelium and the basement membrane. The cytoplasm of the secretory epithelial cells contains granular and agranular endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes and secretory granules. The free surface of the secretory epithelium is furnished with densely arranged microvilli. The apices of the cells protrude as dome-shaped extensions into the glandular lumen. At the tip of these extensions cellular processes of irregular shape are found. The surface of these processes shows no microvilli. They contain densely packed and dilated cisternae of agranular endoplasmic reticulum and free ribosomes. The constriction of the base of these processes and the occasional observation of a 'demarcation membrane' between a process and the secretory cell indicate that these secretory processes become detached from the secretory cells according to the apocrine mode of extrusion. Within the glandular lumen they break down and form secretion. Parallel to this apocrine extrusion the same cells produce secretory granules, the diameter of which measures 300-900 nm. The contents of these granules are released into the glandular lumen by exocytosis according to the eccrine mode of secretion. This resembles the situation in other mammals in which monoptychic glands release their secretory products by means of both apocrine and eccrine extrusion. Therefore monoptychic skin glands should not be classified into apocrine and eccrine glands. Our results corroborate Schaffer's (1927, 1940) more general classification of exocrine glands according to the nature of the secretory epithelium into monoptychic and polyptychic glands.

The lamina cribrosa of Ornithorhynchus (Monotremata, Mammalia).

A vestigial and transitory lamina cribrosa was found in nestling platypus (Ornithorhynchus anatinus). The heads of two nest-young (180 and 333 mm length), one subadult and one adult Ornithorhynchus were serially sectioned and studied with special reference to the development of the nasal region. In nest-young Ornithorhynchus an irregularly shaped bar of cartilage develops at the foramen olfactorium advehens. In the subadult it is largely resorbed, and in the osseous skull of the adult it is completely lacking. Ontogeny and topographical relationships of this bar of cartilage indicate that it is part of a lamina cribrosa. It embraces the ramus medialis of the nervus ethmoidalis and the arteria ethmoidalis, as do the corresponding parts of the lamina cribrosa of Tachyglossus. Compared to other parts of the chondrocranium this bar develops late in ontogeny, as does the lamina cribrosa of other mammals. Therefore, it can be concluded that part of the lamina cribrosa is present for a short period during the ontogeny of Ornithorhynchus, contrary to earlier reports. As in many other water-adapted mammals, the olfactory system of Ornithorhynchus is reduced. This suggests that the rest of the lamina cribrosa of Ornithorhynchus is secondarily reduced. The common ancestor of Ornithorhynchus and Tachyglossidae most probably possessed a lamina cribrosa which can be traced back to the common mammalian stock. The lamina cribrosa developed only once in the phylogeny of mammals. Its lack in the adult Ornithorhynchus is not a "reptilian" character.

Ontogeny and cranial morphology of the tympanic region of the Tupaiidae, with special reference to Ptilocercus.

The structure of the tympanic region of the skull of Ptilocercus lowii was studied in an embryo of 30 mm crown-rump length and in 5 osteocrania. As in Tupaia, the anterior wall of the bulla of Ptilocercus is not completed by a tympanic process of the alisphenoid, contrary to earlier reports. Ptilocercus resembles Tupaia in the following derived characters. The ventral wall of the tympanic cavity is formed by a rostral entotympanic and by a caudal tympanic process of the petrosal. The entotympanic develops in primary connection with the tubal cartilage. The tympanic aperture of the auditory tube is bordered by the entotympanic. The ring-shaped tympanicum is covered by the entotympanicum and is aphaneric. The musculus tensor tympani is lacking. Among mammals, these characters can be regarded as synapomorphic for the Tupaiidae, that is, to have been present in the common ancestor of the two subfamilies. From the evidence of the tympanic region, the Tupaiidae, therefore, form a monophyletic group. Besides these synapomorphies, there are remarkable differences between Ptilocercus and Tupaia in the structure of the bulla. In Ptilocercus the bulla is smaller and less pneumatized than in Tupaia. An anterior intrabullar septum, present in Tupaia, is lacking in Ptilocercus. The epitympanic wing of the alisphenoid is smaller in Ptilocercus than in Tupaia. A lateral prefacial commissure of the tegmen tympani is present in Ptilocercus, but absent in Tupaia. The caudal tympanic process of the petrosal is larger in Ptilocercus than in Tupaia. These characters are autapomorphic for the Ptilocercinae and for the Tupaiinae, respectively. They demonstrate that the auditory bulla of Ptilocercus and that of Tupaia have evolved independently to a considerable extent. An early phylogenetic separation of their respective ancestors seems likely. The tympanic region of the skull provides no evidence for close relationships of the tree shrews to the primates or to any other eutherians. The classification of the Tupaiidae in a separate order, Scandentia, is supported.

[Ontogeny and morphology of the round window and aqueduct of cochlea in Tupaia and other mammals]. / Die Ontogenese und Morphologie der Fenestra rotunda und des Aquaeductus cochleae von Tupaia und anderen Säugern.

Studied the morphogenesis of the Fenestra rotunda and of the Aquaeductus cochleae in a series of 23 dated embryos and postnatal stages of Tupaia belangeri. The ontogeny of the Fenestra rotunda is the result of the caudal growth of the Processus recessus (DE BEER 1937). The Processus arises from the caudal ridge of the floor of the cochlear part of the otic capsule. On the 28th d of ontogeny (the gestation period of Tupaia belangeri is 43 d), it is fused with the lateral edge of the parachordal plate. On the 40th d, the Processus recessus joins the ventral surface of the canalicular part of the otic capsule, which develops a small cartilaginous process to meet it. In Tupaia, the Processus recessus is a large cartilaginous plate in a nearly horizontal position. It does not reach the plane of the Foramen perilymphaticum. The Processus recessus can be regarded as a part of the parachordal plate that was shifted laterally together with the Recessus scalae tympani by the enlargement of the cochlear part of the otic capsule in the ancestors of living mammals. The Processus forms the floor of the Aquaeductus cochleae, by which the laterally shifted Recessus scalae tympani of mammals remains connected with the cranial cavity. The Aquaeductus cochleae contains the Ductus perilymphaticus connecting the Cavum perilymphaticum of the inner ear with the Cavum leptomeningeum. The Fenestra rotunda of mammals is homologous with the lateral aperture of the Recessus scalae tympani of reptiles. In some mammals (e.g. Micropotamogale), the Membrana tympani secundaria spans the lateral aperture of the Recessus scalae tympani, as in many reptiles. Both the Membrana tympani secundaria of reptiles and that of mammals are homologous. Secondarily, in a large number of therian mammals (e.g. Myotis [Frick 1952]), the tympanic cavity extends into the Recessus scalae tympani displacing the Membrana tympani secundaria medially from the lateral aperture of the Recessus scalae tympani (= Fenestra rotunda of mammals) and even into the plane of the Foramen perilymphaticum. Thereby the Fossula fenestrae rotundae is formed, which in bounded medially by the Membrana tympani secundaria.

[Detection of Bacillus cereus-toxins (author's transl)]. / Nachweis von Bacillus cereus-Toxinen.

During the logarithmic state of growth, B. cereus produced extracellular toxins, which could be precipitated by ammoniumsulphate. The toxins were not dialysable. 9 strains of B. cereus were tested and showed lethal, hemolytic, and phospholipase-C-reactions. The lethal toxin injected i.v., killed mice within 20 minutes. An intradermal injection of the 9 toxin-precipitates in rabbits produced skin reactions, which could be neutralized by a specific antiserum against the B. cereus strain B-4ac. Relatively high doses (50 mg/ml) of the toxin caused fluid accumulation after injection in ligated loops of rabbit gut (Tab). The hemolysin of the tested B. cereus strains was found to be thermolabile. The phospholipase-C activity withstood the temperature of 55 degrees C for a period of 10 minutes. The prepared specific antiserum, which inhibited the phsopholipase-C activity totally, had no effect on the hemolysis. Intradermal and enteropathogenic activities point to the presence of an enterotoxin. For detection of the enterotoxin, the skin-test in guinea pigs or rabbits seems to be most appropriate.