Embryology Flashcards
What is the appendix of the testis derived from?
Paramesonephric (Mullerian) duct
What is the ligamentum arteriosum derived from?
Ligamentum Arteriosum = small ligament attaching aorta to pulmonary artery
Ductus arteriosus
What is the ductus arteriosus derived from?
6th aortic arch (left)
When does the anterior pituitary form in the foetus?
Week 5
Complete mole vs Partial mole
Complete: empty egg fertilised by one or two normal sperm: 46XX or 46XY
Diffuse swelling of villous tissue and diffuse trophoblastic hyperplasia in the absence of embryonic tissue
Partial: normal haploid egg fertilised by two or three sperm: 69XXY, 69XXX, 69XYY
Focal swelling of villous tissue and focal trophoblastic hyperplasia in the presence of embryonic tissue
Highest risk time to use warfarin?
6-9 weeks
What remnant of the upper mesonephric duct is commonly seen at laparoscopy?
Epoophoron- remnant of caudal mesonephric duct found next to ovary and Fallopian tube (homologue of male epididymis)- located in lateral part of mesosalpinx.
May give rise to local para-ovarian cyst/ adenoma
What is a Gartner’s cyst?
Remnants of mesonephric duct that are located along anterior and lateral parts of the vaginal wall
What do oocytes develop from?
Primordial germ cells
What is the allantois derived from?
Endoderm & splanchnic mesoderm
Origin of ureteric bud?
Mesonephric duct
What do the ovaries originate from?
The gonads begin as genital ridges – a pair of longitudinal ridges derived from intermediate mesoderm and overlying epithelium.
What are the pharyngeal arches?
In the developing embryo, there are six pharyngeal arches. They arise in the fourth week of development as out-pocketings of mesoderm on both sides of the pharynx.
Each pharyngeal arch has a branch of the aorta, a cranial nerve and a cartilage bar associated with it.
What does cleft palate result from?
Failure of development of the 1st pharyngeal arch: failure of fusion of palatal shelves in the midline.
Derivatives of 2nd pharyngeal arch?
Facial nerve
Muscles of facial expression (buccinator, stapedius, stylohyoid, posterior belly of digastric, platysma)
Temporal styloid process, lesser horn of hyoid bone, stylohyoid ligament, stapes, reacher’s cartilage
Stapedial artery
What is the proximal internal carotid artery derived from?
3rd pharyngeal arch
Derivatives of 1st pharyngeal arch
Trigeminal nerve (V2 and V3)
Muscles of mastication (mylohyoid, anterior belly of digastric, tensor veil palatine, tensor tympani).
Malleus and Incus of middle ear, maxilla, mandible, zygoma and sphenomandibular ligament
External carotid artery
Maxillary artery
Derivatives of 3rd pharyngeal arch?
Glossopharyngeal nerve
Stylopharyngeus muscle
Greater horn (lower part) of hyoid bone
Common carotid artery, internal carotid artery
Derivatives of 4th pharyngeal arch?
Vagus nerve
Superior laryngeal nerve
Pharyngeal/ cricothyroid muscles
Thyroid cartilage, Cricoid cartilage
Subclavian artery
Derivatives of 6th pharyngeal arch?
Vagus nerve
Recurrent laryngeal nerve
Muscles of larynx & oesophagus (except cricothyroid)
Aytenoid cartilages
Cricoid cartilage
Cuneiform cartilage
Corniculate cartilage
Pulmonary artery
Ductus arteriosus
Pharyngeal pouches & their derivatives
1st: tubotympanic recess, middle ear, auditory tube, tubal tonsil
2nd: palatine tonsil
3rd: DORSAL- inferior parathyroid glands, VENTRAL- thymus gland
4th: DORSAL- superior parathyroid glands, VENTRAL- ultimobranchial body
5th: Ultimobranchial body (fuses with lateral lobe of thyroid gland), parafollicular cells (produce calcitonin)
How many days after fertilisation does the blastocyst hatch from the zona pellucida?
5-7
What germ cell layer does the GIT develop from?
Endoderm.
GIT forms via gastrulation from the endoderm of the trilaminar embryo around week 3
What germ layer does the kidney develop from?
Intermediate mesoderm