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At least 19 recordsLinked to original sources
PubMed1979

Morphological observations on the mesonephros in the postnatal opossum, Didelphis virginiana.

The mesonephros of the opossum persists for 3-4 weeks into the postnatal period. Based on our observations of its structure, and the vital dye experiments of others, it appears that the opossum mesonephros is functional during the first 10 days of the postnatal period. The mesonephros of the newborn opossum consists of 35-45 nephron units which are structurally very similar to metanephric nephrons except that they lack a loop of Henle. By the end of the first postnatal week, regression which proceeds in a craniocaudal direction, is observed. By the end of the second week most nephrons show some signs of regression. The regressing mesonephric nephrons are replaced by connective tissue.

Animals↗
PubMed1975

The problem of sampling homologous groups of nephrons during development of the chick mesonephros.

With the aim of defining homologous groups of nephrons in the chick mesonephros at different stages of development, we opened the abdominal wall of 295 White Leghorn embryos at stage HH 26 and marked off 6 segments of equal length at different levels of the organ by Seichert's plastic linear marking method (Seichert 1965), using marks previously introduced into the vertebral column at the same levels as a guide. The embryos were removed after 2-6 days, weighed and classified according to weight. The primordia of the marked vertebrae were identified. The length of the artificially defined segments or their relationships to both poles of the mesonephros were evaluated in projections. The portion of the mesonephros above Th 3 level shorten during the period of observation, while the more caudal segments grow in a craniocaudal gradient. Homologous groups of nephrons can be identified only by the marking technique, except for those at Th 7 level, whose distance from the caudal pole does not alter up to the 11th embryonic day.

Animals↗
PubMedDate not supplied

Human testicular development and the role of the mesonephros in the origin of a dual Sertoli cell system.

Some aspects of the development of the human testis (and overy) are discussed and the main theories regarding gonadal differentiation summarized. The major part of this review deals with the origin and differentiation of the three groups of somatic cellular content: Sertoli cells, Leydig cells and peritubular cells. The most important role of the mesonephros in gonadal development is described. Under the influence of the mesonephros, a second type of meiosis-inducing Sertoli cell differentiates and becomes the opponent of a meiosis-preventing type of Sertoli cell which derives from the coelomic epithelium. All somatic cells are pooled in the central gonadal blastema which is part of the medulla. They migrate via the rete blastema to the sites of their final differentiation. Included are the precursors of the Leydig cells and the peritubular cells.

Cell Differentiation↗
PubMed1977

The role of cellular locomotion in leukemic infiltration. An organ culture study on penetration of L 5222 rat leukemia cells into the chick embryo mesonephros.

The significance of cellular locomotion for leukemic infiltration was investigated using L 5222 rat leukemia cells. Previous cinemicrographic studies have shown that these cells are able to locomote only after formation of a uropod-like posterior extension. This characteristic locomotive configuration of L 5222 cells is easily recognizable in scanning electron micrographs and appropriate sections. Leukemia cells were inoculated on slices of chick embryo mesonephros incubated for 24h; at this time the fragments are completely encapsulated. Leukemic infiltration is found to begin within the first 2 h and to increase gradually up to the end of the observation period at 72 h. Spread of leukemia cells occurs mainly in the intertubular spaces; the tubular epithelium is only rarely affected. In all stages of infiltration, L5222 cells with the characteristic locomotive configuration are frequently recorded. Besides this strong although indirect indication for the significance of locomotion, further evidence was provided by experiments performed at 25 degrees C and 18 degrees C. In accordance with the previous cinemicrographic finding that at these temperatures L 5222 cells are unable to produce their posterior extension, no leukemic infiltration mesonephros fragments is recognizable at subnormal temperatures.

Animals↗
PubMed1978

Scanning electron microscopy of the renal corpuscle of the mesonephros in the lamprey, Entosphenus japonicus Martens.

The renal corpuscle of the lamprey mesonephros was studied under the scanning electron microscope. Bowman's capsules with individual spaces are chockshaped sacs closely packed together along a medial artery. The lateral walls of the capsules are apposed to those of neighbouring capsules. Glomerular capillaries from the medial artery extend radially between the apposed walls of neighbouring Bowman's capsules. Bulgings of capillaries into the capsular space are associated with mesangial folds of the capsular epithelium. The transitional zone of the visceral layer with podocytes and the parietal layer of squamous epithelium is bounded by linearly arranged rod-shaped epithelial cells. Apertures of the urinary tubule are lined by cells equipped with a fascicle of cilia.

Animals↗
PubMed1975

Histochemical localization of Mg2+-Na+-K+-adenosine triphosphatase in different stages of the sheep mesonephros.

Mesonephroi of sheep embryos ranging from 12 to 100 mm C.R. length were examined for the occurrence and localization of transport-ATPase. Native cryostat sections were incubated according to the technique of Guth and Albers for demonstrating the nitrophenylphosphatase activity of Mg2+-Na+-K+-adenosine triphosphatase. The basal cytoplasm of the collecting tubule of the narrow segment of the distal tubule exhibit strong activity, the wide segment of the distal tubule is moderately active. Glomeruli, proximal tubule, and Wolffian duct remain unstained. The basal labyrinths of the reactive nephron segments are believed to be the sites of a Na+-K+ exchange pump. In mature and regressing mesonephroi, the findings fully agree with biochemical data; in maturating mesonephroi, whose basal labyrinth is not yet fully established, the biochemical assay proves to be more sensitive. The specifity of the reaction was ascertained by diverse inhibitors and activating ions. The localization of Mg2+-ATPase is different to the above mentioned reaction pattern, as it shows moderate activity in the proximal tubule, too (mature mesonephros). Mesonephroi of very young embryos exhibit strongest Mg2+-ATPase activity in the proximal tubule; here the distal and collecting tubule stain only moderately.

Adenosine Triphosphatases↗
PubMed1975

[Development of the nephrons of the mesonephros of chicken embryo].

The number of nephron populations in the postinduction period was established in 6- and 8-days chicken embryos and the development of an individual nephron and its parts was studied. The investigation by microdissection method has shownand the number of nephrons is different along the length of the kidney. Only two layers ofthe nephrons were found in the cranial portion, while in the caudal direction their number increased up to 4-6 populations which distinguished from one another by the glomerule position, the length of the nephron and its segments. All the populations of the ventral nephrons enter immediately into the mesonephritic (Wolffian) duct, while the dorsal nephrons have a system ofcollecting tubes by which they are connected with the mesonephric duct. The development of mesonephros was accompained by the increase of the absolute length of the nephrons of all populationsand their segments. Laboratory of Individual Development, Institute of Physiology, Czechoslovakian Academy of Sciences, Prague, and Laboratory of the Evolution of the Kidney and Water-Salt Exchange, Sechenov Institue of Evolutionary Physiologyand Biochemistry, Leningrad.

Animals↗
PubMed1977

[Involution of the mesonephros and differentiation of the epididymis in chickens: immunohistological study].

By means of purified rabbit anti-adult chicken kidney antibodies two types of antigens have been identified in the mesonephros: one, localised in the cells of the proximal segment of the secretory tubules, the other characteristic of the collecting segments derived from the Wolffian duct. During the transformation of certain mesonephric tubules into ductuli efferentes and conjugentes of the epididymis the collecting tubule antigen disappears whereas the proximal secretory tubule antigen not only persists but can also be detected in the parietal layer of Bowman's capsules as they transform before connecting with the rete testis.

Age Factors↗