embryology Flashcards

Question

what is the urinary system comprised of

Answer 1

Kidney, ureter, bladder and urethra

Answer 2

Kidney and ureter develop from three overlapping systems in nephrogenic cord portion of the urogenital ridge - pronephros, mesonephros and metanephros. Kidney develop in the pelvis and then ascends into the abdomen with the final position taken by 12th week. Bladder and urethra are formed from urogenital sinus (part of cloaca) which also give rise to parts of female and male reproductive tract.

Answer 3

The pronephros (non-functional) The mesonephros (functional but transient) The metanephros (final kidney) Metanephric mesenchyme forms kidney and ureteric duct forms the ureter The nephric duct drains into the cloaca which is a common temporary outlet for digestive, urinary and genital tract in embryonic life.

Answer 4

renal agenesis horseshoe kidney pelvic kidney duplex kindeys duplex ureter and cloacal system

Answer 5

The caudal end of the enfolded yolk sac is known as the cloaca. Its covered by the cloacal membrane which is formed by fusion of ectoderm and endoderm The cloaca is divided by the urorectal septum to form - The urogenital sinus - The anal canal The urogenital sinus will form the bladder and urethra The Mesonephric duct below the ureteric bud is incorporated into the bladder as the trigone

Answer 6

The indifferent gonad develops in the gonadal ridge The gonadal ridge is closely related to the mesonephros Primordial germ cells do not originate in the gonadal ridge but migrate to the gonads from endoderm lining of yolk sac via hindgut around 6 weeks of gestation Epithelium of gonadal ridge forms primitive sex cords Combination of germ cells and primitive sex cord forms the indifferent gonad which is capable of developing into a testis or ovary

Answer 7

The Y chromosome contains the SRY gene (sex-determining region Y) SRY produces testis determining factor / SRY protein This protein acts on the indifferent gonad to promote the formation of the testis In rare cases, following a translocation error, a male can be born with a 46 XX Karyotype (1:20,000)

Answer 8

The migrating germ cells enter the ovary The primitive sex cords extend into the medulla but degenerate Secondary sex cords (cortical cords) develop and surround the germ cells to form the ovarian primordial follicles Ovarian follicle pool (determining female ovarian reserve established at 20 weeks of gestation in fetal life

Answer 9

The migrating germ cells enter the testis The primitive sex cords extend into medulla and form testis cords (medullary cords) which transform into future seminiferous tubules and rete testis Sertoli cell are derived from surface epithelium under effect of AMH Leydig cells are produced from intermediate mesoderm and produce testosterone from 8 week onwards

Answer 10

The gonads originate in the posterior abdominal wall The testes reach the deep inguinal ring by 7 months of pregnancy By term 97% of male infants will have fully descended testes Undescended testicle, also known as cryptorchidism requires early surgery for correction

Answer 11

There are two sets of genital ducts Mesonephric duct next to the gonad Paramesonephric duct laterally The presence or absence of AMH determines which develops and which regresses In the male the presence of AMH causes the paramesonephric ducts to regress and these do not form any part of the adult

Answer 12

Mesonephric ducts , also called Wolffian ducts drain the mesonephros into the cloaca In both males and females it forms the trigone part of the bladder Rest of the duct only persists in the males under the effect of testosterone and forms the epididymis, vas deferens and seminal vesicles In females, the duct regresses and remnants might remain as epoophoron, paraophoron (small cystic structures lateral to ovary) and gartners duct cyst (benign lesions on the lateral vaginal wall)

Answer 13

In the absence of AMH, the paramesonephric ducts continue to develop and the mesonephric ducts regress Paramesonephric ducts grow medially and fuse. The fused portions of the paramesonephric ducts canalises to form the uterus and upper 2/3 rd of vagina. The unfused portions give rise to the fallopian tubes Urogenital sinus forms the lower 1/3rd of vagina Paramesonephric ducts fuse with the urogenital sinus at the sinus tubercle and point of fusion forms the hymen

Answer 14

On either side of the cloacal membrane folds develop – The urogenital folds Anteriorly these fuse to form the genital tubercle Lateral to this are the labioscrotal swellings As the cloaca is split by the urorectal septum the anus is separated off

Answer 15

In the male the genital tubercle elongates to form the penis The labioscrotal swelling folds fuse posteriorly The urogenital folds fuse posterior to anteriorly to form the penile urethra (spongy urethra) The glans penis will canulate at the tip to form the final part of the urethra

Answer 16

In the female the urogenital folds form the labia minora The labioscrotal folds form the labia majora The genital tubercle forms the clitoris

Answer 17

Penile- micropenis (genital tubercle does not elongate fully), hypospadias (urethral development problem causing opening to be abnormally located) Testicular- Absence, undescended (cryptochordism) Absence of vas deferens (cystic fibrosis) Absence of seminal vesicles

Answer 18

Anomalies of the female reproductive tract are common 4-7% of women No one agreed classification system: ASRM (AFS) ESHRE/ESGE There is an association with renal tract anomalies

Answer 19

Vaginal anomaly Vaginal Septa Can be longitudinal or transverse (1:80,000) Imperforate Hymen (1:2000) Vaginal Agenesis Absent or underdeveloped uterus and vagina MKRH Syndrome (Mayer–Rokitansky–Küster–Hauser) or Mullerian agenesis syndrome (1:4500) Failure of the paramesonephrict ducts to develop normally

embryology Flashcards

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