splanchnic mesoderm
has vascular function
somatic mesoderm
has structural function
primitive gut/yolk sac
forms from fusion of two embryonic germ cell layers (mesoderm and endoderm)
other parts of the placenta
allantois, chorion, amnion
Before the placenta may form, the mesoderm differentiates into:
splanchnic and somatic mesoderm
mesonephros
temporary kidney from the mesoderm
mesonephric ducts
Wolffian ducts, larger diameter, waste is transported through these to the urogential sinus
mesonephric tubules
initially drains the mesonephros, merge together to form mesonephric ducts
urogenital sinus
shared urinal and reproductive systems, from ectodermal tissue origin
metanephros
true kidney
paramesonephric ducts
Mullerian, form next to the mesonephric ducts
As metanephros grows and becomes functional, mesonephros _____.
regresses
undifferentiated gonad
adjacent to the mesonephros, originates from undifferentiated mesodermal tissue
mesenchyme
undifferentiated mesodermal tissue
differentiation of the gonad is under genetic control by
Sox9, FGF9, Wnt4
gonadal/genital ridge
special region of the indifferential gonad
primordial germ cells
originally found in the lining of the yolk sac, proliferate and then migrate to the gonadal ridge
primary sex chords
form by PGC's stimulating connective tissue in the gonadal ridge, cause enlargement of the gonadal ridge, pushing it toward the mesonephros fusion of the indifferential gonad and mesonephros eventually occurs
chemotactic signal
emitted from the primary sex chords to attract the XY PGC's into the sex chords, attracts other cells too
sustenacular cells
Sertoli, differentiatenon-PGCs that go inside the primary sex chords
interstitial cells
Leydig, non-PGCs that remain outside of the primary sex chords
seminiferous tubules
primary sex chords develop into these
Fox2L gene
regulator gene that suppresses genes promoting development of the testes
secondary sex chords
emit a signal to attract XX PGCs
follicle cells
result of PGCs inducing mesenchymal cells around them to differentiate
monotocous
typically gives birth to one offspring per parturition
polytocous
typically gives birth to more than one offspring per parturition
Freemartinism
an abnormal condition that can result when a female conceptus and male conceptus are gestated in the same uterus
avascularized placental tips
no blood flow; in pigs it is necrotic tips
anterior lobe
develops from ectodermal tissue from the roof of the mouth
posterior lobe
develops from neural (ectodermal) tissue in the brain; highly innervated
innervated
supply an organ or other body part with nerves
diverticulum
infundibulum; results from tissue of the brain starts growing downward toward the mouth, another forms from the tissue from the roof the mouth
Rathke's pouch
diverticulum that forms from the tissue from the roof of the mouth
stomodeum
embryonic mouth; Rathke's pouch becomes isolated from this
adenohypophysis
anterior pituitary
neurohypophysis
posterior pituitary
hypothalamus
special region of the brain
sphenoid bone
bone in skull that forms around both lobes of the pituitary to protect them
sella turica
special cavity formed
allantois
the fetal membrane lying below the chorion; formed as an outgrowth of the embryo's gut; in mammals it forms part of the placenta
amnion
the innermost membrane that enclose the embryo
chorion
the outermost membrane surrounding an embryo
What gene initiates the development of the testes and the male reproductive system?
SRY gene
What PGCs enter the primary sex chords to create which sex in mammals?
mesonephric cells
What PGCs do not enter the primary sex chords to create which sex in mammals?
mesonephric cells
In males, the non-PGC that enter the primary sex chords, and the non-PGC that do not, become what?
sustenacular (Sertoli) cells; interstitial (Leydig) cells
What hormones cause regression of the paramesonephric ducts?
anti-Mullerian hormone; AMH
Why is there no one specific uterus for every species?
species vary in litter size, uterus size, placental size
monozygotic
twins derived from a single embryo; identical
dizygotic
twins derived from two embryos; fraternal
Paramesonephric ducts become what parts of the female reproductive system?
oviducts, uterus, cervix, anterior vagina,
The genital tubercle develops where in the male? Female?
near umbilicus; near anus
What do we see in litter bearing species that keeps Freemartinism from occurring?
avascularized/neurotic placental tips
Anterior lobe develops from what? Posterior lobe develops from what?
stomodeum; infundibulum
What surrounds the pituitary gland for protection?
sphenoid bone