Revision notes: 2. Embryology Flashcards
Name for 16 cell zygote
Morula
Syncitiotrophoblast secretes?
hCG
Process involving formation of 3 germ layers
gastrulation
occurs in 3rd week of development
Ectoderm forms
epidermis
nervous system
mesoderm forms
muscles
skeletal system
connective tissues
endoderm forms
GIT
respiratory tract
endocrine glands
auditory system
urinary system
At what stage does the embryo obtain nutrient from maternal blood via uteroplacental circulation
Day 12
primary chorionic villi formed from
cytotrophoblasts
neural plate formed at day
day 18
primitive heart tube formed at
day 20
1st pharyngeal arch
Trigeminal nerve
Muscles of mastication
2nd pharyngeal arch
Facial nerve (VII)
Muscles of facial expression
3rd pharyngeal arch
Glossopharyngeal nerve
Muscle: stylopharyngeus
4th and 6th pharyngeal arch
Vagus nerve
4th arch: cricothyroid, pharyngeal
6th arch: muscles of larynx and oesophagus
Diagram of pharyngeal arches
Which structure is primary mechanism for shunting blood away from foetal pulmonary circulation
Foramen Ovale
Which structures develop from mesodermal somites
Dermis - dermatomes
Skeletal mucsle - myotomes
Tendons and cartilage - syndetomes
Bone - sclerotomes
Another name for paramesonephric ducts
Mullerian ducts
A bicornuate uterus is due to what?
Abnormal fusion and reabsorption of mullerian ducts
Which structure forms the kidney
metanephros
Mechanism of closure of ductus arteriosus
1st breath leading to inc arterial PO2
Increased bradykinin from lungs, stimulating smooth muscle constriction of ductus
DROP in prostaglandin E2
What percentage of people have a Meckel’s diverticulum
2%
Most potent prostaglandin for maintaining patency of DA during pregnancy
Prostaglandin E2
Somites are derived from which germ layer
Para-axial mesoderm
Diagram of spermatogenesis
In non-pregnant state, which hormones does the corpus luteum secrete
Progesterone (17a hydroxyprogesterone)
Oestradiol
Inhibin A
Which germ layer does the myenteric plexus of the GI tract develop
Neural crest of ectoderm
At term the placenta receives what percentage of uterine blood flow
90%
All hindgut structures are innervated by
T12/L1
Mullerian agensis otherwise known as
Rokitansky-Kuster-Hauser syndrome
Rathke pouch forms what
Adenohypophysis of pituitary gland
i.e. anterior pituitary
Kidney develops from which germ layer
Intermediate mesoderm
When does meconium first appear in fetal terminal ileum
10-16 weeks gestation
Primary site of prostaglandin E2 production
All cells tbh, but placenta and ductus arteriosus have particularly high quanitities of COX enzyme isoforms required for PGE2 synthesis
How many days post fertilisation does the blastocyst enter uterine cavity
4
Kidney forms from the
Metanephric mesoderm
Metanephros is functional from week?
10
Which vessel obstructs ascent of kidney leading to horseshoe kidney
Inferior mesenteric artery
Embryological origin of Allantois
Endoderm
Embrylogical origin of distal 1/3rd of anal canal
Ectoderm of Cloaca
The Pectinate or Dentate line marks junction
Which part of the placenta is in contact with maternal blood
Syncitiotrophoblast
The collecting tubules of the kidney develop from
Metanephric mesoderm
The liver and biliary tree develop from the
Distal Foregut Endoderm
The liver develops as an outgrowth of the endoderm of the distal foregut, as does the gall bladder, bile and cystic ducts.
Gartner’s cyst - embryological origin
Mesonephric duct
The round ligament is a remnant of the
Gubernaculum
The inner cell mass differentiates into
Epiblast and hypoblast
Becomes bilaminar disc
Primary chorionic villi form from the
cytotrophoblasts
Primitive heart tube forms at day
20
Intra-embryonic mesoderm forms from the
Ectoderm
Para-axial mesoderm forms
somites
Intermediate mesoderm forms
Urogenital system
Lateral plate mesoderm forms
Somatic and splanchnic mesoderm
Intra-embryonic coelom forms
Pericardial cavity
Pleural cavity
Peritoneal cavity
Maternal parts of the placenta are derived from
Decidua Basalis
Which villi contain blood vessels
Tertiary chorionic villi
Placenta increta meaning
Invades myometrium but has not breached uterine serosa
placentra percreta meaning
Has breached uterus serosa
which intervertebral disc component is formed form the notocord?
nucleus pulposus
Bartholin’s glands - embryonic origin
Urogenital sinus
Paramesonephric duct in females (otherwise known as mullerian duct)
Forms: Uterovaginal canal (uterus, cervix, fallopian tubes, upper half of vagina), broad ligament
Penile urethra forms from
Cloacal fold
The obliterated umbilical vein becomes the
ligamentum teres
Whenever the intestinal midgut loop fails to return from the umbilical cord into the abdominal cavity, the defect is known as
Exomphalos
Gastroschisis is distinguishable from exomphalos in that exomphalos
Is covered by peritoneum and amnion
Which part of the female urogenital system is described as the Vestibule?
Area between labia minora
Which molecule plays an important role in capacitation?
Heparin
What are the components of Placental barrier at term?
Syncitiotrophoblast and Endothelium
How many oocytes are available at the time of puberty?
400,000
The intraembryonic coelom forms within which structure?
Lateral plate mesoderm
At what age does meconium appear in Fetal terminal ilium
10-16 weeks
Which structure is the origin of the vas deferens
Mesonephric duct
Thyroid cartilage and cricothyroid muscle develop from which Pharyngeal Arch
4th arch
External Carotid artery develops from the
1st pharyngeal arch
Common and internal carotid artery develop from the
3rd pharyngeal arch
Morula forms on day what after fertilisation
Day 4
The 7th cranial nerve develops from which pharyngeal arch
2nd arch
Intrinsic muscles of larynx form from which pharyngeal arch
6th arch
Subclavian artery develops from which pharyngeal arch
4th arch
Muscles of facial expression - which pharyngeal arch?
Muscles of facial expression
