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  • 1
    Electronic Resource
    Electronic Resource
    The pig mesonephros (1985)
    Springer
    Anatomy and embryology 172 (1985), S. 123-132 
    Details
    ISSN: 1432-0568
    Keywords: Pig ; Mesonephros ; Nephron ; Distal tubule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the distal and collecting tunchies of mature pig mesonephroi (41 st gestational day) was studied in perfusion-fixed embryos. In the distal tubule, the three subsegments postulated on the basts of enzyme histochemistry show only minor differences of their luminal surfaces, mostly of cell size. TEM photographs reveal a single cell type with interdigitating basolateral processes, frequently flattened to 30–120 nm lamellae devoid of organelles. Larger interdigitating processes harbor vertically oriented mitochondria in the form of indented plates. The macula densa cells are small, do not interdigitate, and have distended intercellular spaces. The collecting tubule starts with a dorsal convolution, in which intercalated cells (with apical microfolds and numerous mitochondria) occur in addition to interdigitating cells. Further down this segment, the interdigitating cells are gradually replaced by principal cells characterized by interlocking lateral microvilli, basal infoldings, and relatively few organelles. Intercalated cells extend into the Wolffian duct. Although the pig mesonephros has the most differentiated nephron of the mammals studied so far, with metanephros-like cells, its intrinsic urinary concentrating capacity appears to be low in view of its vascularization pattern and nephron architecture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318951
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  • 2
    Electronic Resource
    Electronic Resource
    Epitheloide Fibroblasten im Endometrium des Schafes (1972)
    Springer
    Anatomy and embryology 136 (1972), S. 336-347 
    Details
    ISSN: 1432-0568
    Keywords: Endometrial fibroblasts ; Sheep paraplacenta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die subepithelialen Fibroblasten des Schafendometriums wandeln sich im paraplacentaren Bereich nach etwa 7 Wochen Graviditätsdauer in ein kompaktes Lager epitheloider Zellen um. Charakteristisch sind dabei die Verengung der Intercellularräume, Vermehrung von Hafteinrichtungen und Mikropinocytosevorgängen, das Auftreten von flächenhaften Membraninterdigitationen und glattem endoplasmatischem Reticulum, sowie zahlreichen, z. T. sehr großen Lysosomen und eine Vergrößerung der Golgiapparate. Gedeutet werden diese Befunde als Spezialisierung für trophische Aufgaben. Die Vorgänge erinnern ultrastrukturell an frühe Dezidualisierungsstadien von Mensch und Nagetieren.
    Notes: Summary During gravidity grow the fibroblasts of the subepitheliar paraplacental connective tissue of the sheep uterus into polyhedral, epithelium—like cells forming a distinct layer. This transformation is characterized by a narrowing of the intercellular spaces, an increase in the number of junctional specialisations and pinocytotic vesicles, the appearance of membrane interdigitations, of smooth endoplasmic reticulum, of numerous, frequently large lysosomes, and by the enlargement of the Golgi complex. The physiological significance of this transformation appears to be an improvement in the transport of substances to the fetus via the paraplacental tissue. With respect to their ultrastructural appearance, the changes resemble those of the early stages of decidua formation in man and in rodents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00522621
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  • 3
    Electronic Resource
    Electronic Resource
    Prenatal hematopoiesis and blood characteristics of the cat (1978)
    Springer
    Anatomy and embryology 153 (1978), S. 243-267 
    Details
    ISSN: 1432-0568
    Keywords: Embryology ; Cat ; Prenatal hematopoiesis ; Blood characteristics ; Hematopoietic organs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The blood, yolk sac, liver, spleen, and bone marrow from 65 timed embryos of 22 cats were examined using light microscopic means in six different age categories. Nucleated primitive erythroblasts derived from the yolk sac are mature by the 19th day and represent 98% of the circulating blood cells, some of them found circulating even at birth. Definitive yolk sac erythropoiesis comprises a span of up to 30 days. On the 36th day, hematopoietic contribution drops to 15%. Neutrophils and the first thrombocytes are present on the 17th day, eosinophils and lymphocytes by the 25th day. Hepatic hematopoiesis most likely begins with definitive erythropoiesis on abouth the 20th day; granulopoiesis occurs in the liver on the 25th day. Blood forming tissue in the liver amounts to 28% which drops to 4% at birth. Splenic hematopoiesis begins on about the 36th day but contributes little to the blood. Bone marrow activity begins at mid-term and supplies about 50% of the blood cells on the 45th day. Hematocrit values increase from 22% on the 36th day to 47% at birth, thus exceeding the normal value of adult cats. The red blood cell number increases from 0.8 million/mm3 on the 25th day to 3.8 million on the 45th day and 6.3 million at birth. The total leukocyte count (880 on the 45th day and 6.480 at birth) must be calculated from the differential count of nucleated cells. Primitive erythroblasts represent the most common nucleated cells on the 25th day; on the 36th and 45th day, definitive erythroblasts predominate, but are outnumbered by leukocytes at birth. On the 36th and 45th day, lymphocytes are the predominating cell type in the white blood picture. The contribution of the hematopoietic organs to the feline prenatal blood formation is shown graphically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315928
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  • 4
    Electronic Resource
    Electronic Resource
    The allantoic and amniotic epithelia of the pig: SEM and TEM studies (1979)
    Springer
    Anatomy and embryology 156 (1979), S. 53-72 
    Details
    ISSN: 1432-0568
    Keywords: Pig allantois and amnion ; Scanning electron microscopy ; Secretory cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The epithelial layers of the allantoamnion of pig embryos and fetuses during various gestational ages were studied utilizing SEM, TEM, and light microscopic histochemistry. The allantoic endoderm exhibits a gland-like secretory activity and thereby differs greatly from that of other mammals. On the surface of this unilaminar cuboidal epithelium, the majority of the cells exhibit characteristic short vermiform ridges, while some protruding cells display larger individual microvilli. These two cell types are also distinct in thin sections. The more common “granular cells” with short and blunt microvillous projections and a lobated nucleus are characterized by small, Golgi-derived secretory granules in the apical cytoplasm showing a positive PAS-reaction. They contain vast glycogen deposits. Extensive regions of lateral interdigitations are found. In the younger stages, membrane thickenings of the apical plasmalemma resemble those of the urinary bladder. The cytoplasm harbors many more interwoven filaments than organelles. The second cell type, the “mitochondria-rich cells”, bearing longer apical microvilli in many cases, only constitutes up to 3% of the mucosal cell population. They are frequently flask-shaped, heavily reactive to oxidoreductases, and rich in lysosomes but have smaller glycogen deposits. Mitochondria-rich cells lack secretory granules but have light apical tubules, probably of endocytotic character. These cells can be found in different functional states. The amniotic epithelium is simple squamous in the younger stages and largely resembles that in other mammals exhibiting cells with few organelles but rich in filaments. Each terminal bar consists of a zonula occludens only which may open toward the end of gestation. In older fetuses, small stratified areas of cells sloughing off into the lumen appear as blisters which contain large vacuolated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315715
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  • 5
    Electronic Resource
    Electronic Resource
    Architecture of the mesonephric nephron in pig and rabbit (1979)
    Springer
    Anatomy and embryology 157 (1979), S. 105-112 
    Details
    ISSN: 1432-0568
    Keywords: Pig and Rabbit Mesonephros ; Wolffian body ; Nephron Architecture ; Nephron length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary As a precondition for determining nephron profiles in sections, mature mesonephric nephrons from pig and rabbit embryos were isolated by a maceration technique in order to demonstrate nephron architecture, length, and diameter. In the pig the proximal tubule is largely constant. In the distal tubule the pre-attachment zone shows the greatest variation. The zone of attachment to the corpuscle and the ventrolaterally directed post-attachment coil has a predictable course as does the collecting tubule. In contrast to earlier reports, the nephron shows no drastic differences in tubule diameter and is up to 33 mm long. The proportional length of the three major nephron segments is surprisingly constant. The rabbit nephron, although much shorter (4 mm) and simpler, with an almost S-shaped pattern, is less easily understood in sections. Marked irregularities in its course are caused by the different behaviour of the terminal proximal segment. The distal tubule shows an ampullary dilatation in the attachment zone but can be very narrow in the pre-attachment part.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315643
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  • 6
    Electronic Resource
    Electronic Resource
    The amniotic, allantoic and yolk sac epithelia of the cat: SEM and TEM studies (1979)
    Springer
    Anatomy and embryology 158 (1979), S. 75-94 
    Details
    ISSN: 1432-0568
    Keywords: Cat-Amnion ; Allantois ; Yolk sac ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The epithelial layers of the feline allantoamnion and yolk sac between the 23rd day and full term were studied using SEM, TEM, and light microscopical histochemistry. Amniotic, allantoic and yolk sac fluid were analysed. The attenuated and relatively inert amniotic epithelium sloughs off completely around the 54th day, the amniotic cavity is then lined by fibrous connective tissue only. The exocoelomic epithelium is regarded as the source of the abundant macrophages, rich in lysosomal enzymes, that are seen in the allantoamniotic membrane after obliteration of the exocoelomic cleft. The allantoic epithelium has been mistaken for the amniotic one by many authors. Its cuboidal, glycogen-rich cells develop coral-like luminal outgrowths after the 45th day, which contain almost all kinds of organelles. The basal cell poles form large interdigitations, and the nuclei become heavily lobulated. The changes are accompanied by drastic alterations in the ionic composition of the allantoic fluid. The yolk sac endoderm differs greatly from the allantoic endoderm. It is the most active epithelium of the accessory fetal membranes. The yolk sac mesothelium retains many long microvilli over the whole gestational period. The nutritional value of the yolk sac fluid is only higher than that of the amniotic fluid in its glycerol and cholesterol values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315953
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  • 7
    Electronic Resource
    Electronic Resource
    The pig mesonephros (1983)
    Springer
    Anatomy and embryology 167 (1983), S. 113-123 
    Details
    ISSN: 1432-0568
    Keywords: Pig ; Mesonephros ; Nephron ; Enzyme Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cryostat sections from the mesonephros of various pig embryos with a crown-rump-length of between 17 and 95 mm were used for light microscopical assays of acid hydrolases (acid phosphatase, β-D-N-acetylglucosaminidase, β-D-glucuronidase), oxidoreductases (succinic dehydrogenase, NADH- and NADPH-tetrazolium reductase) and adenosine triphosphatases (Mg2+- and Na+−K+-ATPase). Our main intention was to distinguish more accurately between the different parts of the pig's nephron, which is exceedingly long and coiled. The proximal tubule, that exhibits a high activity for acid phosphatase but none in β-D-glucuronidase incubations, shows no subsegmentation apart from a stronger reaction of its initial segment that was apparent in three of our assays. In the distal tubule, a preattachment convolution, an attachment zone, and a postattachment coil can be discriminated by a synopsis of all histiograms. The beginning of the collecting tubule is situated in the middle of the organ and not at its dorsal face as was previously believed. Up to three different segments can be discriminated in the collecting tubule. The distal and the collecting tubule harbor on ouabain-sensitive Na+−K+-ATPase activity which decreases considerably towards the Wolffian duct. The enzymatic maturation of the mesonephric pig nephron is almost completed in 17 mm embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304605
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  • 8
    Electronic Resource
    Electronic Resource
    The pig mesonephros (1983)
    Springer
    Anatomy and embryology 168 (1983), S. 241-252 
    Details
    ISSN: 1432-0568
    Keywords: Pig ; Mesonephros ; Proximal tubule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the proximal tubule of mature mesonephric nephrons was studied in perfusion-fixed pig embryos of the 41st gestational day. Despite its 8–12 mm long course, the proximal tubule possesses no cytologically different subsegments except its very last cells at the abrupt transition into the distal tubule. The first brush-bordered proximal tubule cells stand considerably within Bowman's capsule, abuting its attenuated cells. In SEM specimens, the average luminal cell diameters are 8×13 μm. The cells are 6–11 μm in height with overlying microvilli 2–4 μ long. Lateral faces of perfectly disjoined cells exhibit plate-like interdigitating processes projecting more than 5 μm deep into the neighboring cells. The basal cell face is completely covered with microvilli. The TEM pictures reveal an endocytic apparatus largely matching its metanephric counterpart. Mitochondria account for 23% of the cytoplasm and together with the many basolateral cell membranes indicate a high capacity for energy-dependent transport processes. Small basal lipid droplets represent a species peculiarity. Freeze-fracture specimens show an electrocoupling of the cells by gap junctions. The tight junction, with only 1–2 strands, characterizes a “leaky” epithelium. In most features, this tissue is as mature as its metanephric counterpart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315819
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  • 9
    Electronic Resource
    Electronic Resource
    The bovine allantoic and amniotic epithelia (1982)
    Springer
    Anatomy and embryology 163 (1982), S. 403-416 
    Details
    ISSN: 1432-0568
    Keywords: Cattle ; Amnion ; Allantois ; Fetal membranes ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ectodermal and endodermal coverings of the allanto-amniotic membrane in cattle fetuses of various gestational ages have been studied by scanning and transmission electron microscopy. We have observed that the allantoic and amniotic epithelia have rather similar cells which are rich in filaments but poor in organelles. Neither epithelium reflects its different origin nor the differences in the composition of the two fetal fluids. Maturation changes occur in the pattern of the various surface specializations until midterm. Coral-like luminal outgrowths, which also contain organelles, were observed in both epithelia, whereas microplicae had formed only on fully differentiated amniotic cells. Interspersed smooth-surfaced cells in the allantoic epithelium that differ also in nuclear shape, glycocalyx, and mitochondria are regarded as a second cell type. Besides fluid-filled blisters and cornified pustules, the most typical feature of the amniotic epithelium is a rather regular lateral cell interdigitation with tongue-like lamellae of even thickness. Micropinocytotic vesicles are more frequent than in the allantois. Both epithelia possess similar tight junctions; no morphological or histochemical indications of an active sodium transport were evidenced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305555
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  • 10
    Electronic Resource
    Electronic Resource
    Intractable diarrhoea in a patient with vasoactive intestinal peptide-secreting neuroblastoma (1981)
    Springer
    European journal of pediatrics 137 (1981), S. 217-219 
    Details
    ISSN: 1432-1076
    Keywords: Neuroblastoma ; VIP ; Somatostatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 1 1/2 year old child developed profuse watery diarrhoea, shown to be due to excessive plasma vasoactive intestinal peptide (VIP) levels, whilst on treatment for metastatic neuroblastoma. Because it was unresponsive to alternative treatment, an attempt was made to control the diarrhoea with a somatostatin infusion. The attempt failed despite the fact that serum VIP levels were substantially reduced. Possible reasons for failure are discussed and the importance of plasma VIP as a marker for maturation in neuroblastoma emphasised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441321
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