Reproductive - FA Embryo etc p598 -610 Flashcards
Mutations in Sonic hedgehog gene leads to what defect?
holoprosencephaly
Wnt-7 gene needed for? produced where?
Produced at apical ectodermal ridge (thickened ectoderm at distal end of each developing limb). Necessary for proper organization along dorsal-ventral axis.
FGF gene stimulates what?
mitosis of underlying mesoderm, to lengthen limbs
If error in Hox gene, what defect?
appendages in wrong locations
Week 1 development
hCG secretion begins @ time of implantation
Week 2
Bilaminar germ disc - epi & hypoblast
Week 3
Trilaminar germ disc
Cells from epiblast invaginate –> primitive streak –> endoderm, mesoderm, ectoderm.
Notochord arises from midline mesoderm; overlying ectoderm becomes neural plate
Weeks 3–8 (embryonic period
Neural tube formed by neuroectoderm and closes by week 4.
Organogenesis. Very susceptible to teratogens
Week 4
Heart begins to beat. Upper and lower limb buds begin to form.
4 weeks = 4 limbs and 4 heart chambers.
Week 6
Fetal cardiac activity visible by transvaginal ultrasound.
Week 8
Fetal movements start.
Week 10
Genitalia have male/female characteristics.
Surface ectoderm
- Epidermis;
- adenohypophysis (from Rathke pouch);
- lens of eye;
- epithelial linings of oral cavity, sensory organs of ear, and olfactory epithelium;
- anal canal below the pectinate line;
- parotid, sweat, mammary glands.
benign Rathke pouch tumor with cholesterol crystals, calcifications
Craniopharyngioma
Neural tube derivs
Brain (neurohypophysis, CNS neurons, oligo- dendrocytes, astrocytes, ependymal cells, pineal gland), retina, spinal cord.
Neural Crest derivs
- PNS (dorsal root ganglia, cranial nerves, autonomic ganglia, Schwann cells),
- melanocytes,
- chromaffinn cells of adrenal medulla,
- parafollicular (C) cells of thyroid,
- pia and arachnoid,
- bones of the skull, odontoblasts,
- aorticopulmonary septum, endocardial cushions,
- myenteric (Auerbach) plexus.
Mesoderm
- Muscle, bone, connective tissue,
- serous linings of body cavities (eg, peritoneum),
- spleen (derived from foregut mesentery),
- cardiovascular structures,
- lymphatics, blood,
- wall of gut tube, upper vagina, kidneys, adrenal cortex,
- dermis, testes, ovaries.
Mesodermal defects
VACTERL
- Vertebral defects
- Anal atresia
- Cardiac defects
- Tracheo-Esophageal fistula
- Renal defects
- Limb defects (bone and muscle)
Endoderm
- *Gut tube epithelium (including anal canal above the pectinate line), *
- Most of urethra and lower vagina (derived from urogenital sinus),
- *Luminal epithelial derivatives (eg, lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, Parafollicular cells of thyroid
Teratogenicity of ACEI?
Renal damage, oligohydramnios, hypocalvaria
Teratogenicity of alkylating agents
Absence of digits, multiple anomalies
Aminoglycosides ?
Ototox
Antiepileptic Rx?
Neural tube defects, cardiac defects, cleft palate, skeletal abnormalities (eg, phalanx/nail hypoplasia, facial dysmorphism)
Diethylstilbestrol
Vaginal clear cell adenocarcinoma, congenital Müllerian anomalies
trimethoprim, methotrexate, antiepileptic drugs.
neural tube defects (folate antagonists)
Methimazole
Aplasia cutis congenita
Tetracyclines
Discolored teeth, inhibited bone growth
Limb defects (phocomelia, micromelia “flipper” limbs)
Thalidomide
Bone deformities, fetal hemorrhage, abortion, ophthalmologic abnormalities
Warfarin - use heparin instead, as it does not cross placenta
Cocaine
Low birth weight, preterm birth, IUGR, placental abruption
Why does smoking cause issues in development?
Nicotine = vasoconstriction. CO = impaired O2 delivery.
Maternal diabetes
- Caudal regression syndrome (anal atresia to sirenomelia),
- congenital heart defects,
- neural tube defects,
- macrosomia, neonatal hypoglycemia
- polycythemia
Methylmercury found in? What teratogenicity?
Highest in swordfish, shark, tilefish, king mackerel. - Neurotox