Embryogenesis of urinary system & reproductive duct
86 Questions
10 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What primarily drives the differentiation of embryonic structures into male external genitalia?

  • Progesterone
  • Testosterone and dihydrotestosterone (correct)
  • Follicle-stimulating hormone
  • Estrogen

    • Which embryonic structure differentiates into the glans penis in males?

  • Urogenital sinus
  • Urogenital folds
  • Labioscrotal swelling
  • Genital tubercle (correct)

    • What is the female equivalent of the bulbar urethral glands in males?

  • Bartholin glands
  • Greater vestibular glands (correct)
  • Urethral glands
  • Skene glands

    • During which weeks does the development of the urogenital sinus occur?

    <p>4-6 weeks</p> Signup and view all the answers

    What is the role of estradiol during the differentiation of external genitalia in females?

    <p>To drive the differentiation of female external genitalia</p> Signup and view all the answers

    What structures are formed in relation to the nephrogenic cord during embryo development?

    <p>Gonads and mesonephric duct</p> Signup and view all the answers

    Which embryonic structure is known as the first excretory organ in humans?

    <p>Pronephros</p> Signup and view all the answers

    At which stage of kidney development does the metanephros appear?

    <p>Final stage</p> Signup and view all the answers

    What divides the cloaca during embryonic development?

    <p>Urorectal septum</p> Signup and view all the answers

    Which part of the urogenital sinus is further subdivided into the vesicourethral canal?

    <p>Cranial part</p> Signup and view all the answers

    What is the fate of the pronephros as kidney development progresses?

    <p>It degenerates</p> Signup and view all the answers

    Which duct persists from the pronephros and is later integrated into the mesonephros?

    <p>Pronephric duct</p> Signup and view all the answers

    Where does the mesonephros arise during embryonic development?

    <p>Thoracolumbar region</p> Signup and view all the answers

    What is the initial location of the kidneys during development?

    <p>Pelvic region</p> Signup and view all the answers

    What happens to the original blood supply to the kidneys during their ascent?

    <p>It degenerates and is replaced by new vessels</p> Signup and view all the answers

    What type of kidney anomaly is characterized by an absence of kidney?

    <p>Agenesis</p> Signup and view all the answers

    From which embryological tissue does the adrenal cortex develop?

    <p>Intermediate mesoderm</p> Signup and view all the answers

    What are the characteristics of cystic kidney dysplasia?

    <p>Kidney with numerous cysts and enlargement</p> Signup and view all the answers

    What condition occurs when a kidney fails to ascend during embryonic development?

    <p>Pelvic kidney</p> Signup and view all the answers

    What determines the phenotypic sex during typical sex development?

    <p>Gonadal sex</p> Signup and view all the answers

    Which congenital anomaly results in the presence of an additional kidney?

    <p>Supernumerary kidney</p> Signup and view all the answers

    During which week of gestation does the first indication of primitive gonad development appear?

    <p>4th week</p> Signup and view all the answers

    What developmental change occurs to the ureters during bladder formation?

    <p>They move laterally and proximally</p> Signup and view all the answers

    What is primarily responsible for the differentiation of testes in male individuals?

    <p>SRY gene</p> Signup and view all the answers

    What do primordial germ cells (PGCs) eventually give rise to?

    <p>Gametes (sperm and oocyte)</p> Signup and view all the answers

    Which anomaly occurs when the ureteric bud crosses the central plane of the kidney?

    <p>Crossed ectopia</p> Signup and view all the answers

    What results from the secretion of Mullerian inhibitory factor (MIF)?

    <p>Suppression of paramesonephric duct differentiation</p> Signup and view all the answers

    Which type of kidney anomaly is characterized by a small size and underdeveloped structures?

    <p>Hypoplasia</p> Signup and view all the answers

    Where does the migration of primordial germ cells take place?

    <p>From the yolk sac to the urogenital ridge</p> Signup and view all the answers

    What are the undifferentiated gonads described as during the indifferent stage?

    <p>Nonbinary and bipotent</p> Signup and view all the answers

    Which gene is associated with the development of ovaries in the absence of a Y chromosome?

    <p>WNT4 gene</p> Signup and view all the answers

    What are the structures called that are involved in the development before sex differentiation occurs?

    <p>Wolffian and Müllerian ducts</p> Signup and view all the answers

    What role does hormonal stimulation play in sex development?

    <p>Secretion of hormones by developing gonads</p> Signup and view all the answers

    What is a key function of the mesonephros during development?

    <p>Contributes to the male genital system</p> Signup and view all the answers

    At what stage does the metanephros begin to develop?

    <p>Starting in the 5th week of development</p> Signup and view all the answers

    What ultimately becomes the cells making up the nephrons in the metanephros?

    <p>Metanephric blastema</p> Signup and view all the answers

    Which structures are formed from the ureteric buds in the metanephros?

    <p>Renal pelvis and collecting tubules</p> Signup and view all the answers

    What is the primary process that allows the growth of metanephric mesoderm and metanephric blastema?

    <p>Reciprocal induction</p> Signup and view all the answers

    What occurs to the mesonephros by the end of the second month?

    <p>It undergoes complete degeneration</p> Signup and view all the answers

    Which of the following structures does NOT originate from the mesonephros?

    <p>Minor calyces</p> Signup and view all the answers

    What is the primary role of Bowman's capsules during the mesonephros phase?

    <p>To filter blood in the absence of other structures</p> Signup and view all the answers

    Which structure is associated with the degeneration of the mesonephros?

    <p>Allantois</p> Signup and view all the answers

    What is the first major interaction that occurs in the development of the metanephros?

    <p>Development of the ureteric bud</p> Signup and view all the answers

    What feature primarily facilitates the descent of the testes through the inguinal ring into the scrotum?

    <p>The gubernaculum</p> Signup and view all the answers

    Which of the following structures undergoes breakdown during male embryonic development, leading to the formation of the primitive urethral folds?

    <p>Urogenital membrane</p> Signup and view all the answers

    At what point in gestation is the descent of gonads expected to be complete?

    <p>Week 33</p> Signup and view all the answers

    What happens to the genital tubercle in male embryonic development?

    <p>It develops into the glans penis</p> Signup and view all the answers

    What structure do the right and left genital swellings fuse to form in males?

    <p>The scrotum</p> Signup and view all the answers

    What is the medial part of the urogenital ridge responsible for developing?

    <p>Genital system</p> Signup and view all the answers

    From which embryonic tissue does the urinary system primarily develop?

    <p>Intermediate mesoderm</p> Signup and view all the answers

    What is the term for the longitudinal elevation of mesoderm that forms along the dorsal body wall?

    <p>Urogenital ridge</p> Signup and view all the answers

    At what week of embryonic development does the formation of the urinary system begin?

    <p>4th week</p> Signup and view all the answers

    Which part of the urogenital ridge is responsible for the development of the urinary system?

    <p>Nephrogenic cord</p> Signup and view all the answers

    What do precursor cells migrate from during the formation of the urinary system?

    <p>Cranial to caudal end</p> Signup and view all the answers

    What structure further delineates the genital system from the urinary system in the urogenital ridge?

    <p>Nephrogenic cord</p> Signup and view all the answers

    What is the function of the kidneys as they develop and migrate?

    <p>To filter waste and produce urine</p> Signup and view all the answers

    What drives the differentiation of male internal organs from the mesonephric ducts?

    <p>Testosterone</p> Signup and view all the answers

    Which of the following ducts gives rise to the female internal sex organs?

    <p>Paramesonephric ducts</p> Signup and view all the answers

    What prevents the differentiation of the mesonephric ducts in female individuals?

    <p>Presence of testosterone</p> Signup and view all the answers

    Which hormone is primarily responsible for the differentiation of female external genitalia?

    <p>Estrogen</p> Signup and view all the answers

    What is the role of dihydrotestosterone in embryonic development?

    <p>Drives the differentiation of male external genitalia</p> Signup and view all the answers

    Which of the following structures degenerates in male individuals due to the influence of testosterone?

    <p>Paramesonephric ducts</p> Signup and view all the answers

    What begins the differentiation of sex organs in males starting from the 7th week?

    <p>Development of mesonephric ducts</p> Signup and view all the answers

    Which embryonic structure acts as the precursor to male internal sex organs?

    <p>Mesonephric ducts</p> Signup and view all the answers

    What is the primary differentiating factor for the development of internal organs in females?

    <p>Absence of MIF</p> Signup and view all the answers

    Which of the following statements is correct regarding the differentiation of sex organs?

    <p>Testosterone is essential for the differentiation of male internal organs.</p> Signup and view all the answers

    What is the role of the SRY gene during sex development?

    <p>It stimulates the differentiation of the testes in male individuals.</p> Signup and view all the answers

    Which embryonic structure gives rise to the primordial germ cells?

    <p>Yolk sac</p> Signup and view all the answers

    Which structure supports the development of the genital ridge?

    <p>Celomic epithelium</p> Signup and view all the answers

    What occurs during the differentiation of embryonic structures in male individuals?

    <p>Development of the prostate gland</p> Signup and view all the answers

    Which hormone is crucial for the differentiation of female external genitalia?

    <p>Estradiol</p> Signup and view all the answers

    What effect does Mullerian inhibitory factor (MIF) have during sex development?

    <p>Inhibits the differentiation of the paramesonephric ducts.</p> Signup and view all the answers

    What does the presence of the WNT4 gene indicate in sex development?

    <p>Differentiation into ovaries in females.</p> Signup and view all the answers

    Which structure develops into the bulbourethral glands in males?

    <p>Urogenital sinus</p> Signup and view all the answers

    Which component is responsible for the differentiation of bipotent gonads into either testes or ovaries?

    <p>Chromosomal sex present at fertilization</p> Signup and view all the answers

    What is the time frame for the start of differentiation of external genitalia?

    <p>Week 9</p> Signup and view all the answers

    Which embryonic structure gives rise to the glans penis in males?

    <p>Genital tubercle</p> Signup and view all the answers

    At what week does the first indication of primitive gonad development appear?

    <p>4 weeks</p> Signup and view all the answers

    The development of which female structure does the absence of dihydrotestosterone contribute to?

    <p>Labia majora</p> Signup and view all the answers

    What structures include the mesonephric ducts and paramesonephric ducts during early development?

    <p>Primitive urinary system</p> Signup and view all the answers

    Which of the following is an accurate sequence of embryonic development as it relates to sex differentiation?

    <p>Chromosomal sex → Gonadal sex → Phenotypic sex</p> Signup and view all the answers

    What is the fate of the urogenital folds during male differentiation?

    <p>Develop into the ventral penile shaft</p> Signup and view all the answers

    Which male external genitalia structure is formed under the influence of testosterone?

    <p>Scrotum</p> Signup and view all the answers

    What is the primary source from which gonads develop?

    <p>Intermediate mesoderm</p> Signup and view all the answers

    What does the urogenital sinus become in both sexes?

    <p>Bladder and urethra</p> Signup and view all the answers

    Which external genitalia structure is a derivative of the labioscrotal swelling in males?

    <p>Penile urethra</p> Signup and view all the answers

    Study Notes

    Urogenital Ridge Development

    • The nephrogenic cord, extending from the cervical to sacral region, forms several structures: excretory renal tubules (para-, meso-, and metanephric), the nephric duct (later mesonephric duct), the paramesonephric duct, and the gonad.
    • The cloaca, divided by the urorectal septum, forms the primitive rectum and the primitive urogenital sinus (subdivided into the vesicourethral canal and the definitive urogenital sinus).

    Kidney Development Stages

    • Three successive kidneys develop from the nephrogenic cord: pronephros, mesonephros, and metanephros, with the metanephros becoming the permanent kidney.

    Pronephros

    • The first rudimentary embryonic excretory organ, arising in the cervical region during weeks 3-4.
    • Composed of a pronephric duct and nephric tubules; has temporary excretory function.
    • Degenerates as the mesonephros develops; its duct persists, becoming the mesonephric duct.

    Mesonephros

    • The second embryonic excretory organ, developing caudally to the pronephros.
    • Arises in the thoracolumbar region during the 4th week.
    • Consists of S-shaped tubules draining into the mesonephric duct (Wolffian duct), forming Bowman's capsule.
    • Most tubules disappear, some contributing to the male genital duct system (epididymis, ductus deferens, seminal vesicle, ejaculatory duct).
    • Functions until the end of the second month, then degenerates. Blood is filtered through glomerular capillaries in Bowman's capsule, traveling down the mesonephric tubule to the cloaca and allantois.

    Metanephros

    • The third embryonic excretory organ, developing caudally to the mesonephros and persisting as the permanent kidney.
    • Arises during the 5th week, canalization complete by the 10th week; matures until weeks 35-36.
    • Develops from the ureteric bud (outgrowth of the mesonephric duct) and the metanephric blastema (condensation of intermediate mesoderm). Reciprocal induction between these structures promotes growth via growth factors.
    • The metanephric blastema forms nephrons. The ureteric bud forms the ureter, renal pelvis, major and minor calyces, and collecting tubules.

    Urinary Bladder Development

    • Initially, the Wolffian ducts and ureteric buds enter the urinary bladder base.
    • Later, they become independent, with ureters moving laterally and proximally, and Wolffian ducts dorsally and caudally.
    • Specialized transitional epithelium develops from the urogenital sinus endoderm.

    Kidney Relocation and Vascularization

    • Kidneys initially are in the pelvic region; they ascend to the abdomen during development. Failure to ascend results in pelvic kidney.
    • The original blood supply degenerates as kidneys ascend; new vessels from the aorta become the mature renal arteries. Persistent original vessels may form additional renal arteries or veins.

    Congenital Anomalies

    • Agenesis (absence of kidney) – bilateral agenesis is incompatible with life.
    • Hypoplasia (underdeveloped kidney)
    • Supernumerary kidney
    • Double kidney
    • Renal dysplasia (aplastic kidney with no parenchyma or cystic kidney with many cysts)
    • Positional anomalies (pelvic kidney, crossed ectopia)

    Adrenal Gland Origin

    • The adrenal medulla derives from neural crest cells near the dorsal aorta.
    • The adrenal cortex develops from the intermediate mesoderm.

    Typical Sex Development Overview

    • Chromosomal sex determines gonadal sex, which determines phenotypic sex.
    • Up to 6 weeks, development is nonbinary: undifferentiated gonads, mesonephric (Wolffian) and paramesonephric (Müllerian) ducts, urogenital sinus, and genital tubercle, swellings, and folds.

    Indifferent Stage of Gonad Development

    • Gonads develop from intermediate mesoderm, coelomic epithelium, and primordial germ cells.
    • The genital ridge appears around week 4, formed by mesoderm condensation and coelomic epithelium proliferation.

    Primordial Germ Cells (PGCs)

    • Originate in the yolk sac, migrating through the vitelline duct to invade the urogenital ridge.
    • Give rise to sperm and oocytes.

    Genetic Influence on Gonad Differentiation

    • Genes at fertilization determine gonad differentiation (testes or ovaries).
    • The SRY gene on the Y chromosome encodes the testis-determining factor (TDF), stimulating testes differentiation.
    • Absence of SRY and the presence of WNT4 lead to ovary development.
    • Müllerian inhibitory factor (MIF), from Sertoli cells, suppresses paramesonephric duct differentiation in males.

    Hormonal Stimulation in Gonad Development

    • Developing gonads secrete hormones influencing further development.

    External Genitalia Differentiation

    • Begins in week 9, driven by estradiol and dihydrotestosterone (DHT) presence or absence.
    • Testosterone converts to DHT (via 5α-reductase), differentiating male genitalia, glands.
    • Estradiol and absence of DHT differentiate female genitalia.

    External Genitalia Development Summary

    • The genital tubercle forms the glans penis/clitoris, corpus cavernosum/vestibular bulbs, and corpus spongiosum.
    • The urogenital sinus becomes the urethra, bladder, and distal vagina/vestibule.
    • Urogenital folds become the ventral penile shaft/labia minora.
    • Labioscrotal swellings form the scrotum/labia majora.

    Embryological Development of the Urogenital System

    • The urinary system develops from intermediate mesoderm and the primitive cloaca, beginning at the 4th week of embryonic development. Precursor cells migrate cranially to caudally.
    • The intermediate mesoderm forms the urogenital ridge after embryo folding. The medial part forms the genital ridge (genital system), and the lateral part forms the nephrogenic cord (urinary system).
    • Typical sex development follows a sequence: chromosomal sex determines gonadal sex, which determines phenotypic sex. Up to 6 weeks, development is identical and non-binary, including undifferentiated gonads, mesonephric (Wolffian) and paramesonephric (Müllerian) ducts, the urogenital sinus, and genital tubercle, swellings, and folds.

    Gonad Development

    • Gonads develop from intermediate mesoderm, coelomic epithelium, and primordial germ cells (PGCs).
    • PGCs, originating in the yolk sac, migrate through the vitelline duct to invade the urogenital ridge, forming gametes.
    • Gonadal differentiation depends on genetic factors: the presence of the SRY gene on the Y chromosome leads to testis differentiation; its absence, combined with the WNT4 gene, leads to ovary differentiation.

    Hormonal Influence on Sexual Differentiation

    • The SRY gene encodes a testis-determining factor (TDF).
    • The presence of testosterone (from Leydig cells) promotes mesonephric duct differentiation into male internal organs, and dihydrotestosterone leads to male external genitalia.
    • Müllerian inhibiting factor (MIF), produced by Sertoli cells, suppresses paramesonephric duct development in males.
    • In females, the absence of MIF allows paramesonephric duct development into female internal organs, and estrogen drives female external genitalia development.

    Ductal Sex Differentiation

    • Paramesonephric ducts develop into the fallopian tubes, uterus, and proximal vagina in females; they degenerate in males. Differentiation is driven by estrogens and suppressed by MIF.
    • Mesonephric ducts develop into male internal organs (seminal vesicles, ejaculatory ducts, epididymis, and ductus deferens) in males; they degenerate into vestigial remnants in females. Testosterone drives their differentiation.

    External Genitalia Differentiation (Week 9 Onwards)

    • Driven by the presence/absence of estradiol and dihydrotestosterone.
    • In males, testosterone converts to dihydrotestosterone (via 5α-reductase), leading to male external genitalia, bulbourethral glands, and prostate gland development.
    • In females, estradiol and the absence of dihydrotestosterone lead to female external genitalia.

    External Genitalia and Urogenital Structures

    • The genital tubercle forms the glans penis (male) or clitoris (female).
    • The urogenital sinus forms the bladder and urethra (both sexes), prostate gland (male), distal vagina and vestibule (female).
    • Urogenital folds form the ventral penile shaft and penile urethra (male) or labia minora (female).
    • Labioscrotal swellings form the scrotum (male) or labia majora (female).

    Descent of Gonads

    • Testes descend caudally from their initial retroperitoneal location through the inguinal ring into the scrotum.
    • Ovaries descend caudally to the pelvic rim. This descent, more prominent in males, is facilitated by the gubernaculum. Descent is generally complete by week 33.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Embryology Of The Urogenital System PDF

    Description

    Test your understanding of the development of the urogenital ridge and the stages of kidney formation. This quiz covers the details of the nephrogenic cord, the evolution of embryonic kidneys, and the structures that arise during development. Perfect for students studying embryology or related fields.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser