Reproduction Flashcards
sonic hedgehog gene
produced at base of limbs in zone of polarizing activity. Involved in patterning along anterior-posterior axis. Involved in CNS development; mutation can cause holoprosencephaly
Wnt-7 gene
produced at apical ectodermal ridge (thickened ectoderm at distal end of each developing limb). Necessary for proper organization along dorsal ventral axis.
FGF gene
produce at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, providing lengthening of limbs.
Hox genes
Involved in segmental organization of embryo in craniocaudal direction. Code for transcription factors. Hox mutations causes appendages in wrong locations
Within 1 week of fetal development
hCG secretion begins around the time of implantation of blastocyst (it sticks at day 6)
Within week 2 of fetal development
bilaminar disc (epiblast, hypoblast. 2 weeks=2 layers
Within week 3 of fetal development
trilaminar disc. 3 weeks=3layers. Gastrulation. Primitive streak, notochord, mesoderm and its organization, and neural plate begin to form.
weeks 3-8 (embryonic period) of fetal development
Neural tube formed by neuroectoderm and close by week 4. Organogensis. Extremely susceptible to teratogens.
week 4 of fetal development
heart begins to beat. upper and lower limb buds begin to form. 4 weeks=4 limbs.
week 6 of fetal development
fetal cardiac visible by transvaginal ultrasound.
week 10 of fetal development
genitalia have male/ female characteristics.
gastrulation
process that forms the trilaminar embryonic disc. Establishes the ectroderm, mesoderm, and endoderm germ layers. Starts with the epiblast invaginating to form the primitive streak.
female genital embryology
Default development. Mesonephric duct degenerates and paramesonephric duct develops.
male genital embryology
SRY gene on Y chromosome produces testis determining factor leading to testes development. Sertoli cells secrete Mullerian inhibitory factor (MIF) that suppresses developent of paramesonephric ducts. Leydig cells secrete androgens that stimulate development of mesonephric ducts.
Paramesonephric duct
mullerian duct. develops into female internal structures– fallopian tubes, uterus, upper portion of vagina (lower portion from urogenital sinus).
Mullerian agenesis
may present as primary amenorrhea (due to a lack of uterine development) in females with fully developed secondary sexual characteristics (functional ovaries).
Mesonephric duct
develops into male internal structures (except prostate)– seminal vesicles, Epididymis, Ejaculatory duct, Ductus deferens (SEED). In females, remnant of mesonephric duct becomes Gartner duct.
Mullerian inhibitory factor deficiency
leads to both male and female internal genitalia and male external genitalia. This can also occur due to lack of Sertoli cells.
5 alpha reductase deficiency
inability to convert testosterone into DHT causing male internal genitalia, ambiguous external genitalia until puberty (when increase testosterone levels cause masculinization.
Septate uterus
Common anomaly. Incomplete resorption of septum. Decrease fertility. Treat with septoplasty.
Bicornuate uterus
incomplete fusion of mullerian ducts. Increase risk of complicated pregnancy.
Uterus didelphys
complete failure of fusion leads to double uterus, vagina, and cervix. Pregnancy possible.
Genital tubercle
becomes glans penis, corpus cavernosum, and songiosum in males and glans clitoris, vestibular bulbs, and greater vestibular glands (of bartholin) in women.
Urogenital sinus
becomes bulbourethral glands (of Cowper), prostate gland, and ventral shaft of penis (penile urethra) in males and greater vestibular glands (of Bartholin), urethral and paraurethral glands (of Skene), and labia minora in women.