Ephemeral, rudimentary glomerular structures in the mesonephros of the mouse

Abstract

The fine morphology of glomeruli present in the mesonephroi of mouse embryos from days 12 to 14 of gestational age is described. The glomeruli are rudimentary, ephemeral structures which probably result from temporary juxtaposition of a blood capillary to the ventral extremity of a mesonephrictubule. Yet, they might possess a certain degree of functionality.While the studies of Leeson (1960) in the rabbit, Davies and Davies (1950) and Zamboni et al. (1981) in the sheep, and De Martino and Zamboni (1966) in the human have shown that the mesonephros in these species has a complex structural organization, the transient kidney of rodents has been said to consist only of tubules and to lack identifiable glomeruli; as such, it is considered to be rudimentary and nonfunctional (Bremer, 1916;Brambell, 1927;Brown, 1931;Torrey, 1943).In a more recent investigation, Vetter and Gibley (1966) demonstrated instead that the mouse mesonephros possesses two types of rudimentary glomeruli external, seen as clusters of epithelial cells protruding into the coelomic cavity from the ventral surface of the organ, and internal, more complex structures in association with mesonephric tubules and blood vessels deriving from the aorta. These authors, thus, concluded that the mesonephros of the mouse is provided with a certain degree of functionality. However, due to the fact that their study was conducted either on paraffin sections stained with hematoxylin and eosin or by histochemical procedures, the report of Vetter and Gibley (1966) failed to elucidate ade quately the structural organization of the glomeruli, an important point if the function of the mouse mesonephros is to be assessed with a reasonable degree of accuracy.In the course of a study on the role played by the mesonephros in the development of the mouse gonads, we were able to observe the occurrence of glomeruli and to study their structural organization to a degree of resolution higher than that with which these structures were described in previous reports. MATERIALS AND METHODSThe mesonephroi of 68 mouse fetuses collected at close intervals of development, from day 9 after vaginal plug detection to term (day 19), were studied. The fetuses were distributed as follows: day 9, three; day 10, three; day 11, four; day 11%, one; day 12, nine; day 12% three; day 13, nine; day 13%, four; day 14, eight; day 15, eight; day 16, six; day 17, four; day 18, three; and day 19, three. The fetuses were fixed in situ by intracardiac perfusion (Abrunhosa, 1972) with 2.5% glutaraldehyde in 0.1 M cacodylate buffer, postfixed in 1% buffered Os04, and then embedded in Epon 812.The tissue was serially sectioned for light microscopy at i-pm thickness, and the sections were stained in 1% aqueous Toluidine blue. Upon reaching areas of interest, the blocks were trimmed and thin-sectioned for electron microscopy . RESULTSIn the mouse, mesonephric glomeruli are rare-occurring structures which are present in extremely limited numbers; they were visualized only in five fetuses-four at day 1 2 a...

Branching ducts similar to mesonephric ducts or ureteric buds in teratomas originating from mouse embryonic stem cells

“…Some mesonephric nephron-like structures had a rudimentary glomerulus in contrast to previous studies of human ES cells that reported the presence of nephron-like structures with discernible glomeruli and tubules in ES cell-derived teratomas (1,43). This discrepancy seems to depend principally on species differences, i.e., the human fetus has a well-developed mesonephros with distinct glomeruli (27), whereas the mouse fetus does not (48). In fact, no discernible vascularized glomeruli were observed in the mesonephros of mouse embryos used as controls.…”

Pkd1 and Pkd2 Are Required for Normal Placental Development

“…These authors were unable to detect a placental defect and concluded that polyhydramnios, which precedes cyst formation, is caused by abnormal proximal tubular function and excessive loss of renal solutes. Our data, however, are not consistent with this conclusion since we see polyhydramnios as early as E11.5, prior to filtration by the metanephric kidney [40]. In addition, Pkd endo− embryos lack a demonstrable renal phenotype yet they have significant polyhydramnios, making it unlikely that this is renal in origin.…”

The development of the sexually indifferent gonad in the prosimian, Galago crassicaudatus crassicaudatus

“…Obvious differences exist between the mesonephroi of primates which display a "conventional" type of organization, are relatively long-lived, function as excretory organs, and are still undergoing differentiation when the gonad begins to develop, and: 1) those of ruminants which not only are prominently developed but also peculiarly organized due to the presence of a giant nephron (Bremer, 1915;Davies and Davies, 1950;Shumkina, 1960;Tiedemann, 1976;Zamboni and Upadhyay, 19821, are highly functional, and are already involuting prior to onset of gonadal development; and 2) those of rodents which are ephemeral, incomplete, non-functional and still in very early formative stages at the time the PGCs arrive in the genital ridge (Bremer, 1916;Brambell, 1927b;Brown, 1931;Torrey, 1943;Vetter and Gibley, 1966;Zamboni and Upadhyay, 1981). Since in primates the mesonephros does not seem to play a critical role in the early assembly of the gonad in sharp contrast to ruminants and rodents where its role as source of the somatic-cell population of the gonadal blastema has been convincingly demonstrated one may speculate in the possibility that the differences in patterns and mechanisms of gonadal development may be attributable to the differences that exist among species with regard to the structural complexity, functionality, and stages of differentiatiodinvolution of their mesonephroi on the one hand, and the time of gonadal development on the other.…”

“…Our laboratory has contributed to the current understanding of the role of the mesonephros in gonadal development with studies in the mouse (Merchant and Zamboni, 1972;Upadhyay et al, 1979Upadhyay et al, , 1981 and the sheep Zamboni and Upadhyay, 1982), animals that are at the opposite extremes with regard to degrees of mesonephric development, structural complexity, and functionality. The mesonephroi of the mouse, like those of the rat (Torrey, 1943), are incompletely developed, rudimentary, and non-functional (Bremer, 1916;Brambell, 1927b;Brown, 1931;Vetter and Gibley, 1966;Zamboni and Upadhyay, 1981); in contrast, those of the sheep and other ruminants are of voluminous dimensions, possess a peculiar organization of considerable complexity, and are fully functional as filtering and excretory organs (Bremer, 1915;Davies and Davies, 1950;Shumkina, 1960;Tiedemann, 1976;Zamboni and Upadhyay, 1982). As a logical evolution of those studies, we decided to focus on gonadal development in the primates not only because of the obvious biomedical relevance of these animals, but also because they are characterized by degrees of mesonephric structural development and complexity which are intermediate between the rodent and ruminant extremes cited above (Torrey, 1954;Davies, 1963;De Martino and Zamboni, 1966;Patten, 1968;Du Bois, 1969;Cotrutz et al, 1971;Hamilton and Mossman, 1972;Koga, 1972;Arey, 1974;Torrey and Feduccia, 1979).…”