Lecture 4 - Embryogenesis Flashcards
Embryonic Germ Layers
- Endoderm
- Mesoderm
- Ectoderm
embryonic origins from the ectoderm
Reproductive Tract
- external vagina or penile sheath
- clitoris or penis
Nervous System
- hypothalamus
- pituitary
Oral cavity
Nasal cavity
embryonic origins from the mesoderm
Repro System
- gonads
- uterus, cervix, internal vagina
- epididymus, ductus, deferens, accessory sex glands
Urinary System
Skeletal System
Blood Vessles
Muscle
embryonic origins from the endoderm
Digestive System
Respiratory System
Glandular Systems
embryonic development of the reproductive system
- development of hypothalamic-hypophyseal systems
- primordial germ cells migrate from yolk sac
- sex cord development in the gonad and mesonephric renal system regression/transformation
- sexual differentiation
- development of female tract and ovaries
- formation of broad ligament
Gestation period of cattle
280-290 days
gestation period of sheep
145-150 days
gestation period of swine
114 days
gestation period of dog
60-65 days
gestation period of cat
63-67 days
Why are the anterior and posterior pituitary so different?
- posterior originates from infundibulum coming from the 3rd ventricle (neural tissue)
- anterior originates from Ratheke’s pouch which was apart of the embryonic mouth (glandular)
Why do germ cells migrate into the gonadal ride of the embryo?
to form any tissue type
What does the repro system develop in close proximity to?
renal system
Three embryonic renal systems
- pronephroes
- mesonephros
- metanephros
Pronephros
most primitive form of kidney found in developing embryo- limited fxn and eventually degenerates
Mesonephros
- early kidneys of emrbyo regresses and gives way to metanephros
- remnants of regressing mesonephric renal system become portions of repro tract
What do remnants of regressing mesonephric renal system become?
- mesonephric ducts = male repro tract
- paramesonephric ducts = female repro tract
Metanephros
final renal system that becomes fxning kidneys
Sex determining factors
Female
- no TDF
- ovaries develop
- no AMH
- Paramesonephric duct becomes the oviducts, uterus, cervix and part of the vagina
- complete female tract
Where is AMH secreted from
sertoli cells of the testis
What female organ does the paramesonephros duct turn into?
- oviducts, uterus, cervix, cranial vagina
What female organ does the mesonephros duct turn into
regresses
What female organ does the urogenital sinus turn into?
urethra, caudal vagina
Gonadal dysgenesis
- incomplete development of gonads
- ex. Turner syndrome; only 1 X chromosome so ovary doesn’t fully develop
Hermmaphrodites
-have both ovarian and testicular tissues
- ex. FREEMARTIN
