Mesoderm-3rd week

Pronephros & mesonephros-4th week

Urogenital ridge 4th week

Urinary system-4th week

4-5 week

Mesonephric vesicle

Mesonephric tubules

metanephros

Metanephric kidneys

Metanephric kidneys

5th week

6th-7th week

8th-9th week

12th week

Relocation of Kidneys 6th & 7th week

Relocation of Kidneys 8th & 9th week

Renal anomalies Renal agenesis – Potter Sequence Renal dysplasias – multicystic dysplastic kidney Cong. polycystic kidney D. Autosomal dominant Autosomal recessive Duplication of ureter

Renal Anomalies Disorders due to malrotation Often associated with ectopic kidneys Malrotated kidneys Supernumerary kidneys Fused kidneys- crossed renal ectopia Divided kidney with bifid ureter

Renal Anomalies Disorders due to positional changes Accessory renal arteries Accessory renal veins Pelvic kidneys Horseshoe kidneys Pancake kidneys

Bladder Anomalies Urachal fistula Urachal sinus Urachal cyst Exstrophy of bladder Exstrophy of cloaca

Multiple Renal Arteries

Multiple Renal Veins

Unilateral Renal Agenesis

Pelvic Kidney

Malrotation of kidney

Crossed Renal Ectopia

Discoid Kidney

Supernumerary Kidney

Urachal Cyst

Urachal Sinus

Urachal Fistula

Development of gonads 4th week- primordial germ cells 5th week – Gonadal ridge 6th week – Incorporation of cells into gonadal cords Upto 7th week – Indifferent gonad Y- chrosomome- SRY gene for TDF in sex determining region of y ch. Y chromosome has a testis determining effect on medulla of gonad Type of gonad formed will further differentiate development of genital ducts and external genitalia

Development of gonad Mesothelium- (of post. Abd. Wall) Mesenchyme Primordial germ cells- large sperical cells among endoderm of yolk sac near allantois Gonadal ridge- mesothelial thickening on medial side of mesonephros + mesenchyme Prim. Germ cells migrate along dorsal mesentery to gonadal ridge

Indifferent gonad Gonadal Ridge Gonadal cords (Fingerlike epithelial cords) Gonad consists of cortex & medulla xy xx Testis ovary

Indifferent Gonad

Indifferent Gonad

Differentiation of Gonads

Ovaries

Testis Condensation of cords Extension into medulla Branching & anastomoses-rete testis Tunica albuginea develops Connection of cords with surface nis lost S. tubules, T recti & rete T Mesenchyme- interstitial cells in 8th wk- hormones S tubules remain solid till puberty

Hormones in male 8-12 wk- peak of HCG --- Testosterone & androstenedion from Leydig cells MIS / AMH from Sertoli cells

Mesonephric duct & tubules Mesonephric tubules --- Efferent ductule + paradidymus in male Epoophoron & paroophoron in female M duct prox. Part --- duct of epididymus, appendix of epididymus M duct distal part ---URETERIC BUD + ductus deferens, ejaculatory ducts & seminal gland Appendix vesiculosa, duct of epoophoron & Gartner’s duct in female + URETERIC BUD

Descent of the Testis The process vaginalis, (evagination of peritoneum), develops ventral to the gubernaculum and herniates through the abdominal wall along the path formed by the gubernaculum The vaginal process carries extensions of the layers of the inguinal canal In males these layers also form the coverings of the spermatic cord and testis The opening in the transversalis fascia produced by the vaginal process becomes the deep inguinal ring The opening created in the external oblique aponeurosis forms the superficial inguinal ring.

Descent of Testes Enlargement of the testes Atrophy of the mesonephroi Atrophy of the paramesonephric ducts Enlargement of the processus vaginalis Enlargement of fetal pelvis Trunk elongates Androgens Descend retroperitoneally Gubernaculum Increased intra abdominal pressure due to viscera .

Development of Inguinal Canals The inguinal canals form pathways for the testes to descend from the abdomen into the scrotum Develop in both sexes because of the indifferent stage As the mesonephros degenerates, a ligament – the gubernaculum – descends on each side of the abdomen from the inferior pole of the gonad The gubernaculum passes obliquely through the developing anterior abdominal wall at the site of the future inguinal canal The gubernaculum attaches caudally to the internal surface of the labioscrotal swellings (future halves of the scrotum or labia majora).

Role of Gubernaculum Uncertain Forms a path for processus vaginalis Anchors testes to scrotum Guides its descent

Effects of descent of testes Ductus deferens and vessels are carried with testes Testis and ductus deferens are ensheathed by fascial extensions Transversalis fascia ---- internal spermatic fascia Internal oblique muscle and fascia --- cremasteric muscle and fascia External oblique aponeurosis --- external spermatic fascia In the scrotum the testis projects into the distal end of the processus vaginalis.

Cryptorchidism or Undescended Testes Unilateral or bilateral The testes fail to descend uptill the end of the first year May fail to mature and sterility is common (bilateral) Often histologically normal at birth, but failure of development and atrophy are detectable by the end of the first year May be in the abdominal cavity or anywhere along the usual path of descent of the testis Usually in the inguinal canal Cause mostly unknown Deficiency of androgen production by the fetal testes is an important factor Increased risk of developing testicular cancer

Congenital Inguinal Hernia Communication between the tunica vaginalis and the peritoneal cavity fails to close, a persistent processus vaginalis exists. A loop of intestine may herniate through it into the scrotum or labium majus Hydrocele Abdominal end of the processus vaginalis remains open but is too small to permit herniation of intestine. Peritoneal fluid passes into the patent processus vaginalis and forms hydrocele of the testis If the middle part of the processus vaginalis remains open, fluid may accumulate and give rise to a hydrocele of the spermatic cord.

Ducts in male

Urinary bladder & Prostate

Hormonal Influence on Sex Differentiation Testis Mullerian inhibiting Testosterone Substance (Sertoli cells) (Leydig cells) Paramesonephric ducts suppressed Mesonephric ducts stimulated & form epididymis & vas deferens Ovary Estrogens Paramesonephric ducts stimulated & External genitalia stimulated & Form uterine tube, uterus, upper form labia, clitoris & lower portion of portion of vagina vagina

Uterus & Vagina Three parts of paramesonephric ducts Fimbriated end of fallopian tube Body of fallopian tube Uterovaginal primordium formation by union of paramesonephric ducts Mesoderm forms broad lig. & parametrium Uterovaginal primordium grows towards sinus tubercle in urogenital sinus Sinovaginal bulbs & vaginal plate formation

Uterus &Vagina 9 Weeks 12 Weeks Newborn

Paramesonephric ducts & urogenital Sinus

Paramesonephric ducts & urogenital Sinus

Paramesonephric ducts & urogenital Sinus

Ducts in Female

Development in Female

Descent of the Ovaries Descent of the gonads in female is much less. Ovaries move and settle just below the rim of the true pelvis. Cranial genital ligament forms the suspensory ligament of the ovary, where as the caudal genital ligament forms the ligament of the ovary proper and the round ligament of the uterus. The later extends into the labia majora.

Adult Derivatives Male Embryonic Structure Female Paramesonephric Duct Uterine tube Uterus Urinary bladder Urogenital Sinus Urinary bladder Urethra Urethra Prostatic gland Vagina Bulbourethral glands Urethral & paraurethral glands Greater vestibular glands Sinus Tubercle Hymen Penis Phallus Clitoris Glans penis Glans clitoris Corpora cavernosa penis Corpora cavernosa clitor. Corpus spongiosum penis Bulb of vestibule Ventral aspect of penis Urogenital Folds Labia minora Scrotum Labioscrotal swellings Labia majora

Normal Uterus & Vagina

Double uterus & double vagina Uterus Didelphys & vagina duplex

Uterus didelphys &single vagina

Bicornuate uterus

Bicornuate uterus with rudimentary horn

Septate uterus

Unicornuate uterus

Ambiguous sex - Intersex True Hermaphroditism- have testicular & ovarian tissue Extremely rare, 70 % 46xx, 20% mosaicism, 10%46xy presence of both testicular & ovarian tissue-nonfunctional ovotestes phenotype variable with ambiguous external genitalia Female Pseudohermaphroditism- have ovaries 46 xx, chromatin +, exposure of excessive androgens to female fetus (C.Ad.Hyper.) excessive progesterone in threatened abortion maternal tumours Male Pseudohermaphroditism- have testes 46xy, chromatin -, external & internal genitalia are variable, testis rudimentary to normal inadequate testosterone & MIS Genetic defects in enzymes for production of testosterone

Ambiguous sex Androgen Insensitivity Syndrome Mixed Gonadal Dysgenesis (testicular Feminization Syndrome) 46 xy, testes present, normal appearing female Female external genitalia, Uterus & Ut. tubes rudimentary or absent, Vagina ends in a blind pouch Normal breast development but no mensturation Testes are in abdomen or ing. Canals Resistance to testosterone at cellular level Mixed Gonadal Dysgenesis Testis on one side & undiff. gonad on other side Internal genitalia female External genitalia variable

External Genitalia Sexually undifferentiated stage. Genital tubercle --- at the cranial end of the cloacal membrane. Labioscrotal swellings and urogenital folds develop on each side of the cloacal membrane The genital tubercle form a primordial phallus Urorectal septum fuses with the cloacal membrane, it divides the cloacal membrane into anal membrane b. Ventral urogenital membrane. The anal and urogenital membranes rupture forming the anus and urogenital orifice. In female the urethra and vagina open into the vestibule.

Male External Genitalia Masculanizaion of indifferent gonad by testosterone Phallus forms penis Urogenital folds form spongy urethra Urogenital folds form walls of urethral groove on the ventral surface of penis Urethral groove is lined by endodermal cells of urethral plate Surface ectoderm fuses forming penile raphae & encloses spongy urethra Cords forms at the tip and canalize to form urethral orifice Labioscrotal swellings form the scrotum

External Genitalia Genital tubercle Urethral groove Urogenital orifice Urogenital fold Labioscrotal fold Anus 7th Week Old Embryo 9th Week Old Embryo

External Genitalia of 12 Week Old Fetus Glans penis Glans clitoris Urethral groove Urethral orifice Vestibule of vagina Labia minora Labia majora Scrotal raphe Scrotum Anus Male Female

External Genitalia In Female 5 Week Embryo Newborn

Urethral orifice abnormalities Epispadias Urethra opens on dorsal surface Urogenital sinus opens on dorsal surface Urine is expelled at the dorsal surface of malformed penis Hypospadias The external urethral orifice is on the ventral surface of penis (penile hypospadias) These defects result in failure of canalization of ectodermal cord or failure of fusion of urogenital folds