Histogenesis Of Human Fetal Renal Medulla

Introduction: Histogenesis of kidney gives knowledge regarding histological maturity of kidney and its functionalstatus at the given gestational age. Kidney is developed from two parts, metanephrogenic blastema and uretericbud. Metanephrogenic blastema gives origin to secretory part i.e. nephron while ureteric bud forms the collectingpart i.e. collecting tubules and ureter. Both these parts fuse with each other and the development becomescomplete.Materials and Methods: 50 aborted human fetuses between 13-36 weeks of gestational age were used for thisstudy with no obvious congenital anomalies. The 2-3 mm thick cut sections of both kidneys were taken, processedand Paraffin blocks were prepared. 5-7 micron thick sections were taken with rotary microtome, mounted andthen stained with Haematoxylin and Eosin. Microscopic features were observed in low and high power and thendocumented.Results and Discussion: Differentiation between cortex and medulla was seen from 16-18 week onwards. Themedulla with collecting ducts, thick and thin segment of loop of Henle became well differentiated from 16 weekonwards. Vascularity of medulla increased with increase in gestational age while connective tissue decreasedwith increase in gestational age. Renal pelvis was lined by transitional epithelium.

Development of the Fetal Ureter: A Fetal Metric and Histological Study

@#Introduction: This study provides a description of development of various components of the human ureter at different gestational ages. Methods:Measurements of the length of the ureter from pelvi-ureteric junction to vesico-ureteric junction, length of its intravesicular portion and angle made by the ureter at the entry into the bladder with respect to the internal ureteric orifice were taken. Transverse sections of the ureter were taken at the upper end, close to the pelvi-ureteric junction, and at the midpoint between the pelvis of the kidney and the vesico-ureteric junction. These were subjected for processing and stained with Haematoxylin Eosin and Masson’s Trichrome. They were then studied under the light microscope. Results: The length of the ureter from the pelvi-ureteric junction to the vesico-ureteric junction showed a highly positive correlation with the gestational age (GA). The angle of entry of the ureter to the bladder decreased as the GA increased. The microstructure of the ureter in both the sections showed development of transitional epithelium with an increase in layers by 33 weeks. At 18 weeks, the smooth muscle layer was in a single layer with an abundance of interspersed collagen fibers. By 33 weeks, the thickness of the wall increased significantly with a decrease in collagen. There was no trace of longitudinal muscle fibers even upto 33 weeks. Conclusion: Epithelial, muscular and connective tissue components displayed significant changes during intra uterine development.

Keratinizing Desquamative Squamous Metaplasia of the Upper Urinary Tract: A case report

Keratinizing desquamative squamous metaplasia of the transitional epithelium occurs rarely in the upper urinary tract, especially in the ureter. It is associated in most cases with long-standing chronic inflammation but the exact pathogenesis is unknown, and the relationship to cancer has continued to be controversial. More cases should be accumulated for a better assessmnt of this lesion. Recently, we experienced a case of keratinizing desquamative squamous metaplasia in the renal pelvis, adjacent calyces and ureter following acute and chronic pyelonephritis. Herein, we are presenting our case with a review of literatures.

An Experimental Study on the Sequential Changes of the Irradiated Transitional Epithelium of the Urinary Bladder in Rats. An Ultrastructural Observation with Special Reference to Polyploid Cells / 대한비뇨기과학회지

Polyploid cells in the urinary sediments often give an erroneous clinical judgement in cases of post-pelvic irradiation follow-up, but their nature and evolution have remained unclarified. An experimental induction of polyploid cells in the transitional epithelium of the urinary bladder was carried out in Sprague-Dawley rats by administration of 3,000 rads in a single dose, and their sequential morphological changes were analysed under light and electron microscopes. 1. The acute post-irradiation changes of transitional epithelial cells were manifested with two consecutive phases of degenerative process ; the early lesion started to appear from the first day after irradiation and diminished partly at the 7th day; the later changes became enhanced progressively from the 2nd week and maximized at the 3rd week, but regressed thereafter . 2. The general histological alterations of the transitional epithelial cells in the acute stage were characterized by cytoplasmic vacuolization due to profound widening of intercellular cisternal spaces and dilatation of smooth endoplasmic reticulum aside from severe disruption of mitochondria and increase of lysosomes, especially in the superficial and intermediate cells, and by eventual outcome of cell death by nuclear pyknosis and karyorrhexis. 3. The polyploid cell change was demonstrated as a spectrum of the later alterations of acute irradiation injury to the basal layer cells, and appeared early from the 2nd week and regressed after the 4th week. 4. Based on their increased size and nuclear abnormalities, those polyploid cells exhibited features of both amitotic nuclei and cytoplasmic degenerative processes ultrastructurally, and in the acute phase the nuclear indentation and lobulation were associated with increased amount of heterochromatins and margination together with nucleolar enlargement and increase in number. 5. The above cells started to regress thereafter, being terminated by nuclear pyknosis and karyolysis, and numerical reduction of the polyploid cells was accompanied concomitantly with basal (reserve) cell hyperplasia of the remained epithelium. It is of the author's assumption that the polyploid cell phenomenon induced by irradiation onto the transitional epithelium of the urinary bladder is a transient manifestation of irradiated amitotic basal cells during the later phase of acute post-irradiation injury and is subsequently removed out by nuclear pyknosis and karyolytic processes.

HISTOLOGICAL AND HISTOCHEMICAL STUDIES OF DEVELOPING TRANSITIONAL EPITHELIUM OF RAT URETER AND URINARY BLADDER / 解剖学报

The development of transitional epithelium of ureter and urinary bladder in the rats from prenatal 15 days old to postnatal 4 weeks old was studied by histological and histochemical methods. During the development, RNA and glycogen contents are increased at first and then decreased. The activity of SDH,AcP and AlP increased gradually and ATPase reaction was negative. These parameters tended to be stable from the postnatal 3rd week, it meants that the epithelium tend to maturation. On the prenatal 15th day there were some significant differences between the epithelium of the two organs, however thereafter they gradually become identical and they showed the same type of epithelium, i.e. transitional epithelium at maturation. This means that they reached the same goal by different routes. In addition, on the prenatal 15th day the epithelium of urinary bladder stratified in most portions, some of the superficial cells degenerate. Hence it deduced that the epithelium of urinary bladder undergo primitive stratification firstly, nad then cell degeneration happens, and evolve into trasitional form ultimately. Meanwhile, We presume that in certain extent, the development of the epithelium of the two organs, including cell temporary degeneration, in addition to the action of embryonic induction, probably related to the content of urinary tract also.