Embryology of Reproductive System Flashcards
Gastrulation begins with…
Formation of primitive streak
Describe the process of gastrulation
Conversion of the epiblast from a bilaminar disc into a trilaminar embryonic disc consisting of a definitve mesoderm and endoderm
Mesoderm is organised into 3 groups. What are they?
Paraxial plate
Intermediate plate
Lateral plate
The urogenital system arises from which germ cell layer?
Intermediate mesoderm
Which common cavity do excretory reproductive ducts open into during development?
Cloaca
Describe the formation of genital ridges
Proliferation of coelomic epithelium into somatic support cells, which envelope primordial germ cells (origins of sperm and oocytes)
Describe the formation of the indifferent gonad
Two genital ridges penetrate and invade the underlying mesenchyme forming finger-like primitive sex cords
State the two genital ducts formed during the ambisexual phase of development
Mesonephric (wolfian) duct - MALES
Paramesonephric (mullerian) duct - FEMALES
What structure do the genital ducts connect to?
Urogenital sinus
Sexual differentiation occurs from week _ onwards
7
Male development is triggered by the absence/presence of sex determining region of Y transcription factor
Presence
Somatic support cells develop to form what cells? What are they stimulated by?
Sertoli cells
SRY transcription factor
Which structure connects the mesonephric tubules to the testis cords?
Rete testis
What exists between coelemic epithelium and testis cords?
Tunica albuginea
Thickened layer of CT
List the functions of sertoli cells in development
Secrete anti-Mullerian harmone (AMH) causing degeneration of paramesenephric duct
Stimulate gonadal ridge cells to form Leydig cells
What is the function of Leydig cells?
Production of testosterone –> dihydrotestosterone
The production of testosterone stimulates which male structures to form?
Epididymis
Vas deferens
Seminal vesicles
The production of dihydrotestosterone stimulates which male structures to form?
External genitalia
Prostate
Which spinal level do the testis orginate from?
T10
Name the ligament which pulls the testis caudally during development
Gubernaculum
Failure to descend one or both testis is known as…
Cryptorchidism
List the 3 male accessory glands formed during development and the relative origin of each
Prostate (endoderm) Bulbourethral glands (endoderm) Seminal vesicles (mesonephric duct)
Female development is triggered by the absence/presence of sex determining region of Y transcription factor
Absence
Primary oocytes are differentiated from which cells?
Germ cells
Granulosa cells are differentiated from what cells?
Somatic support cells
Primordial follicles are formed from…
Primary oocytes surrounded by granulosa cells
Paramesonephric ducts are formed under the influence of what sex harmone?
Ovarian oestrogens
Paramesonephric ducts give rise to which structures of the female reproductive system?
Uterine tubes
Uterus
Superior vagina
List the 3 main parts of a paramesonephric duct
Cranial portion (opens into coelomic cavity) Horizontal portion (crosses mesonephric duct) Caudal portion (fuses paramesonephric duct on opposite side)
What is the function of the uterovaginal canal
Fused caudal portion of paramesonephric ducts give rise to uterus and superior vagina
How is the paramesonephric portion of vagina, sinuvaginal bulbs and fornices formed?
Vacuolization of vaginal lumen
How is the spongy urethra in males formed?
Proximal to distal zipping of urethral groove
Which germ cell layer forms the tip of the glans penis and the foreskin?
Ectoderm
What is hypospadias?
External urethral opening lies in abnormal position along ventral aspect of penis
