This section of notes gives an overview mainly of adult renal histology, see also Renal System Development notes.
Page also provides further background information for Medicine phase 1 Health Maintenance B Urinary Tract Histology Practical Virtual Slides.
- Nephron - Functional unit of kidney
- Humans up to 1 million
- Filtration of waste from blood
- Blood pressure regulation
The key structure of the adult nephron is the glomerulus (renal corpuscle), which represents the initial vascular/renal interface.
- mean glomerular number shown to level at 36 weeks, increasing from about 15,000 at 15 weeks to 740,000 at 40 weeks.
Can be described anatomically by its 4 layers from outside inward:
- Serous - the superior or abdominal surfaces and the lateral" surfaces of the bladder are covered by visceral peritoneum, the serous membrane (serosa) of the abdominal cavity, consisting of mesthelium and elastic fibrous connective tissue.
- Muscular - the detrusor muscle is the muscle of the urinary bladder wall.
- Submucosa - connects the muscular layer with the mucous layer.
- Mucosa - (mucus layer) a transitional epithelium layer formed into folds (rugae).
- The adult detrusor muscle consists of three layers of smooth (involuntary) muscle fibres.
- external layer - fibres arranged longitudinally
- middle layer - fibres arranged circularly
- internal layer - fibres arranged longitudinally
- The adult ureter is a thick-walled muscular tube, 25 - 30 cm in length, running from the kidney to the urinary bladder.
- Anatomically can be described in two parts the abdominal part (pars abdominalis) and pelvic part (pars pelvina).
- The ureter is composed of three layers: outer fibrous layer (tunica adventitia), muscular layer (tunica muscularis) and mucous layer (tunica mucosa).
- The muscular layer can also be subdivided into 3 fibre layers: an external longitudinal, a middle circular, and an internal longitudinal.
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bladder exstrophy - A congenital malformation with bladder open to ventral wall of abdomen (between umbilicus and pubic symphysis) and may have other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).
blastema - Term used to describe a mass of undifferentiated cells. (More? Wilm's tumour)
diabetes insipidus - The disorder is related to the hormone antidiuretic hormone (ADH, also called vasopressin) its synthesis, secretion, receptors and signaling pathway. In diabetes insipidus there is an excretion of large amounts (up to 30 litres/day) of a watery urine and an unremitting thirst.
hydronephrosis - (congenital hydronephrosis, Greek, hydro = water) A kidney abnormality due to partial or complete obstruction at the pelvi-ureteric junction. This leads to a grossly dilated renal pelvis causing extensive renal damage before birth.
hyperplastic rests - In kidney development, embryonic blastema cells can persist and proliferate to form a pool of cells, which under either genetic or epigenetic influence can then change to become a neoplastic rest. Normally the majority of nephrogenic rests either regress or become dormant.
mesonephros - The second temporary stage of kidney development (pro-, meso-, meta-). The intermediate mesonephros develops and disappears with the exception of its duct, the mesonephric duct, which will form the male reproductive duct system. In males, the mesonephric tubules go on to form the ducts of the testis. In females, these degenerate. A few mesonephric tubules remain as efferent ductules in the male and vestigial remnants in the female.
mesonephric duct - (= Wollfian duct) An early developing urogenital duct running the length of the embryo that will differentiate and form the male reproductive duct system. In females this duct degenerates (some remnants may remain associated in broad ligament).
metanephros - The adult kidney, third stage of mammalian kidney (pro-, meso-, meta-) development within the intermediate mesoderm.
metanephric cap - In kidney development, the intermediate mesoderm which surrounds the ureteric bud and will develop into nephrons.
Multicystic Kidney - There is no functional kidney tissue present in the kidney and it is replaced by a multilocular cyst. This is non-familial and is produced by atresia of a ureter and is always unilateral.
neoplastic rest - In kidney development, a neoplastic rest can develop under either genetic or epigenetic influence from a hyperplastic rest, originating from an embryonic blastema cell. Normally the majority of nephrogenic rests either regress or become dormant.
nephrogenic rest - A kidney term used to describe the embryonic blastema cells which persist and under either genetic or epigenetic can change to become a neoplastic rest. These neoplastic rests can develop postnatally as a benign form (adenomatous rest) or a malignant Wilm's tumour form. The rests are further characterised by the time of generation leading to different anatomical kidney locations: early intralobar nephrogenic rests (within the renal lobe) and late pelilobar nephrogenic rests (periphery of the renal lobe) nephron - (Greek, nephros = kidney) The functional unit of the kidney.
nephros - (Greek, nephros = kidney) Term used to describe features associated with the kidney. (pronephros, mesonephros, metanephros, nephric, nephron, nephroblastoma).
podocyte - (visceral epithelial cell) kidney glomerulus cell forming the main component of the glomerular filtration barrier.
podocyte specific proteins - podocalyxin, glomerular epithelial protein-1, podocin, nephrin, synaptopodin, and alpha-actinin-4), podocyte synthesized proteins (vascular endothelial growth factor and novH), transcription factors (WT1 and PAX2).
pronephros - (Greek, pro = before) The first temporary stage of kidney development (pro-, meso-, meta-). This forms the kidney of primitive fish and lower vertebrates. Kidney development occurs within the intermediate mesoderm interacting with endoderm. In humans, this very rudimentary kidney forms very early at the level of the neck. It is rapidly replaced by the mesonephros, intermediate stage kidney, differentiating in mesoderm beneath.
proteinuria - The abnormal presence of protein in the urine and an indicator of diesease including diabetic kidney disease (DKD, diabetic nephropathy).
renal - (Latin, renes = kidney) Term used in relation to the kidney and associated structures (renal pelvis, renal artery)
ureter - The two ureters are hollow tubes that link and carries urine from kidney to the bladder. The tubes have a muscular wall lined with transitional epithelium.
urethra - The single muscular tube that links and carries urine from the bladder to the exterior. In humans, the urethral length differs between the sexes (male longer, female shorter).
urinary - Term used to describe all components of the kidney system including the bladder, ureters and urethra.
urine - Term used to describe the liquid waste produced by the kidney, stored in the bladder and excreted from teh body through the urethra.
urorectal septum - (URS) The structure which develops to separate the cloaca (common urogenital sinus) into an anterior urinary part and a posterior rectal part.
Wilms' tumour - A form of kidney/renal cancer (nephroblastoma) named after Dr Max Wilms who first described the tumor. This childhood kidney cancer is caused by the inactivation of a tumour suppressor gene (BRCA2) or Wilms tumor-1 gene (Wt1) and is one of the most common solid tumors of childhood, occurring in 1 in 10,000 children and accounting for 8% of childhood cancers. Wt1 also required at early stages of gonadal development. (More? OMIM - Wilm's tumour | Dr Max Wilms)
Wilms' tumor 1-associating protein - (WTAP) protein expressed in extraembryonic tissues and required for the formation of embryonic mesoderm and endoderm.
Wolffian duct - (= mesonephric duct, preferred terminology), runs from the mesonephros to cloaca, differentiates to form the male vas deferens and in the female regresses. Named after Caspar Friedrich Wolff (1733-1794), a German scientist and early embryology researcher and is said to have established the doctrine of germ layers. (More? Caspar Friedrich Wolff)
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Cite this page: Hill, M.A. (2021, October 22) Embryology Renal System Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Renal_System_Histology
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