Embryology Flashcards
what makes up the female reproductive system?
what makes up the male reproductive system?
what is shown here?
Blastocyst
Blastocyst – outer layer of cells that goes to form the placenta and membranes
Inner ball of cells that goes to form the embryo proper
The blastocyst is a structure formed in the early development of mammals. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast
Ectoderm ___, Mesoderm in ______, endoderm ______
Amniotic cavity _______ and yolk sac _______
Neural tube = ______________
Paraxial mesoderm = _______
Intermediate mesoderm = _____________
Lateral mesoderm = ____________
top
middle
bottom
above
below
brain and spinal cord
somite’s
forms urogenital systems
forms the bodies cavities
Intermediate plate mesoderm forms the ________ system
urogenital
timeline of events:
Weeks 1 & 2 – ________ formed
Week 3 – ________ (splits into 3 germ layers), neurulation (neural tube forms), _______ formation (paraxial mesoderm)
Weeks 4 – 8 - __________ period
Week 9 onwards – _________ of organ systems
blastocyst
gastrulation
somite
organogenetic
maturation
But…..Reproductive system Organogenesis:
- _________ beyond 8 weeks
- Extends beyond _________ period
Extends
post-natal
- Reproductive and urinary systems have close ___________ links
- Urinary system forms _________ for reproductive (part) system
embryological
template
Urinary system development - recap:
- 3 sets of kidneys develop
- _________ – cervical region – vestigial
- _________ – thoracolumbar region – briefly functional
- ________ – pelvic region – functional
- Each acts as template for subsequent stage
Pronephros
Mesonephros
Metanephros
Pronephros, Mesonephros and Metanephros develop from what?
intermediate plate mesoderm
pictures show the week 5 embryo:
The ___________ that goes to start developing the reproductive system
Mesonephric ducts drain into the ______
Mesonephros is no longer ________ as part of the urinary system so is refunctioned to form the ______
mesonephros
cloaca
function
gonads
At about _ weeks mesonephros forms a long ovoid structure in association with thoracic and upper lumbar vertebrae
_______ part of mesonephric ridge becomes thickened to form a ___________ ridge
_______ ridge forms the substance of the ______
6
Medial
genital/gonadal
Gonadal
gonads
(Anteromedial part of the mesonephros (in blue in bottom right) thickens to form genital ridge)
Need cells that can undergo meiosis so they need to be undifferentiated and you wont find them in these 3 germ layers so need to import them form the _____ ____
Germ cells migrate into Genital ridge = ________ _______
- Week 6 - ____ cells migrate from yolk sac, via dorsal mesentery, and embed into primitive sex cords (formed from mesenchyme of genital ridges)
- This structure is known as the _________ gonad (why?) – no difference between male and female at this stage
- No migration of germ cells - no ________
yolk sac
Indifferent Gonad
Germ
indifferent
gonads
what is the Paramesonephric duct?
Epithelium of the mesonephros invaginates to form a tube
This tube becomes the para-mesonephric duct
Paramesonpheric duct:
Develops lateral to developing gonads and __________ duct
Funnel shaped cranial end opens into __________ cavity
Caudally, cross ventral to __________ ducts
This projects into dorsal wall of _________ sinus
mesonephric
peritoneal
mesonephric
urogenital
what are the 3 main strucutres which go on to form the reproductive sytem in males and females?
- Indifferent gonad (with primordial sex cells that have moved in from the yolk sac)
- Mesonephric duct (Wolffian duct)
- Paramesonephric duct (Mullerian duct)
in males:
- Gonad forms _______
- Mesonephric duct develops into _______________________________
- Paramesonephric duct ____________
- Urogenital sinus forms ______________________
testis
epididymis, vas deferens, seminal vesicle,
degenerates
bladder, urethra; and prostate
In females:
- Gonad forms the ______
- Mesonephric duct ____________
- Paramesonephric duct forms ______________________
- Urogenital sinus forms ______________________
ovary
degenerates
fallopian tube, uterus, cervix part of vagina
bladder and lower part of vagina
How does the indifferent gonad know whether to develop into a testis or an ovary? (Only difference is chromosomes)
what is the proccess in men? fill in the blanks in the picture
study this histology
Sertoli cells have much lighter nucleus
Leydig cells in-between seminiferous tubules
what is the process of testis development?
sex cords, medulla and cortex
Wk 6 priWk 5 – primary mordial germ cells incorporated into primary sex cords
Wk 7 – TDF stimulates primary sex cords - extend into medulla - seminiferous cords - tubules
Seminiferous cords branch, ends anastomose - rete testis of medulla
Surface epithelium (mesothelium) lost when thick capsule forms (tunica albuginea of adult testis)
Mesenchyme between cords gives rise to Interstitial cells of Leydig
By week 8, Leydig cells produce testosterone and other hormones which stimulate masculine differentiation of mesonephric ducts and external genitalia
In males, paramesonephric duct degenerates
Testis – post natal development
what photo of the testis is prepubertal and which is postpubertal?
At puberty the seminiferous tubules become canalised and the Leydig cells make more testosterone
Reproductive system development doesn’t fully complete until puberty
Seminal vesicles - Outgrowth from caudal end of ___________ duct
Prostate - Outgrowth(s) from _______ (from urogenital sinus)
Male external genitalia formed under the influence of __________
mesonephric
urethra
testosterone
__________ duct disappears in females, opposite to males
Mesonephric
