Repro/Embryology

Question 1

Origin of anterior pituitary

Answer 1

Surface ectoderm (Rathke’s pouch -> adenohypophysis). Note that the neurohypophysis (posterior pituitary) comes from neuroectoderm

Question 2

Origin of parafollicular cells in thyroid (C-cells) and bones of the skull

Answer 2

Both are neural crest derived!

Question 3

Birth defect from phenytoin and carbamazapine taken during pregnancy

Answer 3

Fingernail & phalynx hypoplasia

Question 4

Mechanism by which alcohol causes fetal alcohol syndrome

Answer 4

Failure of cell migration

Question 5

Implantation of zygote timing?

Answer 5

~7 days (6-10). Cleavage of monozygotic twins occurs around this same time. When it happens just after implantation -> monochorionic, diamniotic twins (most common)

Question 6

Only branchial cleft that persists into adulthood?

Answer 6

First branchial cleft: external auditory meatus

Question 7

Branchial arch 3 derivatives

Answer 7

CN IX: Stylopharyngeus muscle, greater horn of hyoid bone. Note most other things that will cause confusion in this area are arch 2 derivatives (CN VII).

Question 8

Derivative of all intrinsic muscles of the larynx?

Answer 8

Mostly arch 6 (CN X, recurrent laryngeal) except for cricothyroid: arch 4 (CN X, superior laryngeal)

Question 9

Adult derivatives of genital tubercle

Answer 9

Men: glans penis, corpus cavernosum and spongiosum (when positioned improperly develops into epispadias)

Women: clitoris and vestibular bulbs

Question 10

Adult derivatives of urogenital folds

Answer 10

Men: ventral shaft of penis/urethra (defect in fusion causes hypospadias)
Women: labia minora (NTBCw/ labioscrotal swellings that become labia majora)

Question 11

Embryologic origin of prostate gland

Answer 11

Urogenital sinus: note this means that DHT stimulates prostate development while testosterone stimulates devo of rest of male internal structures from Wolffian duct (mesoneprhic)

Question 12

Site of urethral injury from pelvic fracture

Answer 12

Posterior urethral membranous urethra (immediately distal to the prostate). Anterior urethra (bulbous and penile segments) at risk from straddle injury

Question 13

Name of fully mature sperm in lumen of seminiferous tubule? Options: spermatogonium, spermatids, spermatozoon, spermatocyte

Answer 13

Spermatozoon. Order of development: : spermatogonium, spermatocyte, spermatids, spermatozoon (“Zooming to egg”)

Question 14

Most consistent part of menstrual cycle across all women

Answer 14

Luteal/secretory phase (post-ovulation) is exactly 14 days

Question 15

3 types of estrogens and their sources

Answer 15

Estradiol: ovaries (most potent), Estrone: adipose, estriol: placenta (least potent)

Question 16

Two middle ear muscles invovled in dampening sound and their innervation

Answer 16

Tensor tympani: CN V3

Stapedius muscle: CN VII

Question 17

Mechanism of HPV virulence to cause cervical cancer

Answer 17

Inhibition of p53 (E6 gene) and inhibition of Rb (E7 gene)

Question 18

Immature vs. mature teratomas (ovarian neoplasms)

Answer 18

Mature teratoma is benign, contains teeth, hair, etc and can contain thyroid tissue
Immature teratoma is malignant and contains neuroectoderm & embryonic-like tissue

Question 19

Danazol MOA (Hint: repro/endo)

Answer 19

Used in treatment of endometriosis. Decreases estrogen production by ovaries and displaces testosterone from binding protein. Net hypo-estrogen, hyper-androgen affect

Question 20

Most important prognostic factor in malignant breast tumors

Answer 20

Axillary lymph node involvement (suggests metastases)

Question 21

Tender breast with inflamed looking skin that resembles an orange peel (woman is not breastfeeding). Dx?

Answer 21

Peau d’orange breast caused by lymphatic invasion of breast carcinoma. Neoplastic cells block lymphatic drainage, no bueno

Question 22

Clomiphene MOA

Answer 22

Antagonist of estrogen receptors in hypothalamus. Loss of negative feedback increases GnRH secretion. Used to stimulate ovulation in PCOS