Embryo Flashcards
What are the 4 embryonic genes?
- sonic hedgehog
- FGF
- Wnt-7a
- Homeobox (Hox) Genes
What is the SHH gene and what are its main roles?
Makes Sonic Hedgehog protein, which is an embryonic signalling protein; *limbs, brains, eyes.
Key Roles: CNS and Limb dev.
Est. the midline.
What results in a mut. of the sonic hedgehog gene?
Holoprosencephaly; baby does not have a right or left side of brain. SINGLE LOBE brain.
cyclopia, cleft lip.
what is the FGF gene and why is it important?
Fibroblast growth factor. needed for aprical ectodermal ridge dev.
What factor in important in the Dorsal-Ventral dev.?
Wnt-7a; key for dorsal dev. “Dorsalizes the the mesoderm”, Wnt-7a activates the LMX-1 gene.
How is the Wnt gene important in early embryogenesis and later embryogensis?
early embryogenesis; regulators of dorsal-ventral axis.
Late embryogenesis; anteroposterior axis
The zone of polarizing activity is ~w/ dev. in what plane?
A-P; SHH are important in this dev.
homeosis: ?
transformation of one structure into another; leads to formation of body segments.
What genes are important regulators of AP axis dev.?
Homeobox genes
issues with Homeobox genes –> ??
abnormal limb formation; polydactyly/syn-
- Haploid mature spermatozoon (?N, ?C)
- Haploid ovum (?N, ?C)
- Forms zygote (?N, ?C)
- Haploid mature spermatozoon (1N, 1C)
- Haploid ovum (1N, 1C)
- Forms zygote - (2N, 2C)
What is the difference between a morula and a blastula?
blastula has fluid filled cavity called a blastocoel
blastocyst implant in uterus around day ?
day 6-10; beta-hCG starts to be secreted by the placenta
what forms the bilaminar disc?
the inner cell mass
epiblast dev. into what?
embryo.
what devs. into the embryo?
the epislast
what does the hypoblast dev. into?
yolk sac
presence of what indicates start of gastrulation?
presence of the primitive streak
which of the 3 germ layers does the nervous system come from?
Ectoderm; because your nervous system dev. from an involution of the ectoderm. neural fold and neural crest cells make up the mature nervous system
which of the 3 germ layers does the notochord arise come from?
Mesoderm; adult remnant: nucleus pulposus of spine
what does the neural tubes go on to become?
CNS; neurons, oligodendrocytes; astrocysts; retina; spinal cord.
Whas does the neural crest go on to become?
PNS: CNs, dorsal root ganglia, Autonomic ganglia, schwann cells.
microglia and meninges are from?
mesoderm
airway cartilage of the pulm. is from?
mesoderm
What is NOT found in adults (except as stem cells) and rises rise to CT (bones, cartilage, lymphatics & circulatory system?
Mesenchyme; mesenchymal tumors = sarcoma
what is the embryo origins of:
ant. pit (adenohypophsis):
Post. pit (neurohypophysis):
adenohypophsis: from rathke’s pouch of ECTODERM; outpouching of upper mouth.
neurohypophysis: from neural tube
what is the embryo origins of:
Adrenal Gland Cortex:
Adrenal Gland Medulla:
Adrenal Gland Cortex: MESODERM; makes aldo, cortisol, androgen.
Adrenal Gland Medulla: NCC; makes Epi/NE
- missing organ caused by missing embryonic tissue?
- missing organ d/t growth failure of embryonic tissue?
- incomplete organ dev.?
- agenesis; renal agenesis
- thymic aplasia; DiGeorge synd.
- Hypoplasia; microcephaly.
Abnormal development of a structure == ??
Malformation; NT defects, cleft lip/palate, congenital heart defects.
extrinsic error in dev. Disruption = ?
normal tissue growth arrested d/t to external forces; amniotic band syndrome. fetal structure entrapped by fibrous bands in utero (involves limbs or digits)
extrinsic error in dev. Deformation = ?
external forces to abnormal growth (NOT arrested); deforms or misshapes structures; POTTER syndromes
What prego class are ACEi and ARBs in?
Class D; only use if benefits outwieghs risk in life/death situations. leads to congential malformations and oligohydromnios.
What are the highest risk chemo agents for use in pregos?
Alkalating agents and anti-metabolites; leads to spont. abortions, missing digits.
what ADR can Methotreate cause in pregos?
NTD; prego class X
What is Warfarin Embyropathy?
- bone and cartilage abnorms.
- stippled epiphyses
- nasal and limb hypOplasia
What is Methimazole used to Tx and what effects does it have on pregos?
Tx Hyperthyoidism.
in pregos: Aplasia Cutis; absence of epidermis on scalp. use PTU in the 1st-trimester instead. “missing patch of skin/hair in neonate”
S/Sx of fetal alcohol syndrome:
- facial features; smooth philtrum, short palpebral fissures, thin vermillion border (upper lip)
- cong. heart defects: [ASD/VSD/ToF]
- skeletal anomalies; limb defects, small head.
- intellectual disabilities; low IQ, abnormal reflex, small brain.
how does smoking lead to impair Oxygen delivery to fetus?
nicotine-induced vaso-CONSTRICTION –> decrease placental blood flow –> CO competes with O2 ==> decreased oxyhemoglobin.
How does cocaine use affect fetus?
Cause vasoconstriction.
- IUGR/low birth-wight; miscarriage, prematurity
Babies of pregos with Maternal Diabetes have what?
Neonatal HypOglycemia: baby makes excess insulin. so after baby is born, it has a transient (~24hr.) hyper-insulinemic state.
what congential heart defect is ~w/ Maternal DM?
Transposition of the Great Arteries (TGA); also can have VSDs, ASDs.
what is Caudal Regression Syndrome?
Saacral agenesis–incomplete development of the sacrum; ~w/ GDM, may include sirenomelia=”mermaid syndrome”. maye also present with NTD
Fetal Heart issue ~w/ mom’s who have PKU?
coarctation of aorta
Pharyngeal Arch 1 nerve and structures: ?
CNV (maxillary & mandibular br.); maxilla/mandible
Pharyngeal Arch 2 nerve and structures: ?
CNVII (facial); hyoid
Pharyngeal Arch 3 nerve and structures: ?
CNIX (GP); Hyoid
Pharyngeal Arch 4/6 nerve and structures: ?
CNX (vagus); Larynx
What is Treacher Collins Synd?
FIRST arch issue; failure of NCC migration==> underdev. facial bones (w/ glossoptosis–retraction of tongue). may lead to breathing difficulty d/t underdev. lower jaw and obs. of airway by tongue
micrognathia: ?
small jaw
what genetics is involved in cleft lip & palate?
multifactorial; genetic and enviromental
In cleft lip:
1 - nasal prominences fuse to form: ?
2 - maxiliary prominences are from pharyngeal arch: ??
3 - maxillary prominences fuse with medial nasal prominences fuse to form what?
1 - forms philtrum
2 - 1st pharyngeal arch
3 - primary palate.
Failure leads to cleft lip
**Cleft Palate is d/t to failure of palatal processes
Eustachian tube is from what?
first pharyngeal pouch
2nd pharyngeal pouch = ?
lining of the palatine tonsils (back of throat); invaded by mesoderm and lymphatic tissue
3rd pharyngeal pouch = ?
Thymus; left and right inferior parathyroid glands; dorsal (back) = parathyroid; Ventral wing (front) = thymus
4th pharyngeal pouch = ?
superior parathyroid glands; ultimobranchial body (ventral wing) == -C-Cells (calcitonin).
DiGeorge = failure of what ?
failure of 3rd and 4th pharyngeal POUCH!
Pharyngeal clefts are lined by what?
ectoderm
What does the 1st Pharyngeal clefts become?
external auditory meatus; also contributes to the tympanic membrane.
what do the 2nd to 4th Pharyngeal clefts become?
for cervical sinus, a temporary cavity and obliterated in development.
What is a branchial cleft cyst?
a neck mass. 2nd cleft cysts MC. below the angle of the mandible, anterior to the sternocleidomastoid muscle, can become infected and painful. [DOES NOT move with swallowing]
What is the difference between a branchial cleft cyst and a thyroglossal duct cyst?
branchial cleft cyst DOES NOT move with swallowing.
thyroglossal duct cyst is a MIDLINE mass and moves when you swallow.
What is the difference between a branchial cleft cyst and a thyroglossal duct cyst?
branchial cleft cyst DOES NOT move with swallowing.
thyroglossal duct cyst is a MIDLINE mass and moves when you swallow.
What make up the INTERNAL gential tracts of a male and female?
Male: epididymis, vas deferens, seminal vesicles
Female: Fallopian tubes, uterus, upper vagina
what releases MIF?
sertoli cells; suppress the dev. of paramesonepheric ducts
paramesonephric ducts form the internal structures b/c why?
only happen in the absence of MIF and androgen; Fallopian tubes, uterus, upper 2/3 vagina
bladder is from what embryonic structure, regardless of gender?
upper portion of the urogential sinus
where does the inferior part of the vagina come from?
pelvic portion of the urogential sinus; in males this becomes the prostate and the prostatic urethra
- Partial fusion of mullerian ducts = ?
- Mullerian ducts fail to fuse = ?
- Other ovary not connected to uterus = ?
- Partial fusion of mullerian ducts = Bicornate
- Mullerian ducts fail to fuse = Uterine didelphys
- Other ovary not connected to uterus = Unicornate uterus.
in males; failure of urethal folds to close = ?
Hypospadia
abnormal formation of the genitalia tubercle on males = ?
Epispadia
