embryology-10-reproductive system

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genetic gender comes from where: karyotype: established at fertilization
phenotypic sex is what?: structural gender. develops over first 3 months
development of phenotypic sex involves what structures: gonads, accessory organs, genitals
if development is normal, what occurs: genotype determines gonad, gonad determines hormones produced, hormones determine which gender of accessory organs and genitals that develop.
gross anatomical diffs between M&F: 1st 7 wks?: NONE. Can tell males only by presence of Y chromosome, and expression of HY antigen
first event of indifferent stage: gonad appears on posterior abdominal wall, medial to mesonephros
gonad appearance referred to: gonadal or genital ridge
genital ridge tissue structure: intermediate mesoderm core, with covering of epithelial lining of body cavity (coelom)
what are sex cords?: cord-like extensions of coelomic epithelium penetrating mesoderm of genital ridge
what is between the sex cords?: intermediate mesoderm
stimulates further development of gonad?: primordial germ cells appear near origin of allantois, migrate to genital ridges, arrive at genital ridges and enter sex cords
timing of germ cell migration: appear at 4th week, arrive at 6th week
what do primordial germ cells come from?: epiblast
if no Y chromosome, what happens to sex cords?: begin to fragment
what do germ cells become if no Y chromosome: oogonia (primary oocytes)
what do sex cord cells become if no Y chromosome: follicular cells around oocytes
If Y chromosome (and SRY gene) germ cells become: spermatogonia
if Y chromosome, sex cords do what?: elongate to form seminiferous tubules
if Y chromosome, sex cord cells become: sertoli cells
secreted by the cells the sex cords become if Y chrom.?: sertoli cells secrete antimuellerian hormone
if Y chromosome, what do intermediate mesoderm cells between the sex cords of genital ridge become?: Leydig cells, which secrete testosterone
two phases of testicular descent are: trans-abdominal and trans-inguinal
describe the first phase of test. descent: trans abd: from post abd. wall Â– deep ring: passive. gubernaculm tethers testis, fetus grows around it, testis goes to deep ring via differential growth
describe the 2nd phase of test. descent: trans-inguinal: during 7th month, happens over two days, active process
first structure through inguinal ring during desc. is?: processus vaginalis, acquiring coverings as it goes
where are ductus and testicular vessels after descent: within spermatic cord
distal part of processus vaginalis becomes what: tunica vaginalis
what triggers testicular descent: probably hormones
undescended testis Â–term/description: cryptorchid testes, usually on normal line of testicular descent, but not fully into scrotum
testis not where would normally be called: ectopic testis
ovarian descent arrested where: pelvis
gubernaculum between ovary and uterus becomes: ligament of the ovary
gubernaculum between uterus- labium majus becomes: round ligament of the uterus
indifferent stage of access. sexual organs develop from: first as tubular invaginations of coelum near cranial end of mesonephros
indifferent stage of access. sexual organs grow where: caudally alongside mesonephric ducts, into pelvis
entering pelvis, paramesonephric ducts do what?: cross anterior to mesonephric ducts, fuse together in the midline, forming uterovaginal primordium
uterovaginal primordium is located where: posterior to urogenital sinus
at caudal tip of uterovaginal primordium?: makes contact with posterior wall of urogenital sinus, triggering endoderm proliferation toward uterovaginal primordium
mass of endoderm created between urogenital sinus and uterovaginal primordium called: vaginal plate or sinovaginal bulb
If male, cascade of sex differentiation is:: SRY gene=testicle develops: germ cells become spermatogonia;sex cords elongate, become seminiferous tubules;cells of sex cords become sertoli cells, secrete anti-muellerian factor; genital ridge mesoderm cells become leydig cells, secrete testosterone
If testicle present, what is induced?: antimuellerian from sertoli cells induces paramesonephric ducts and uterovaginal primordium to undergo regression
after regression, remnants of uterovaginal primordium?: prostatic utricle and appendix of testes
androgens from leydig cells diffuse into adjacent tissues, inducing what three processes?: mesonephric excretory tubules link with rete testes, forming efferent ductules, mesonephric duct develops into epididymis, vas deferens and ejaculatory duct, and seminal vessicles grow out of mesonephric ducts
If no testicle present, paramesonephric ducts become: uterine tubes
If no testicle, uterovaginal primordium develops into: uterus
if no testosterone present (i.e. no testicle) mesonephric ducts: regress and degenerate
mesonephric duct remnants in broad ligament are called: epoophoron and paroopharon
mesonephric duct remnant near uterus is called: gartners cyst
vagina develops from what two structures: uterovaginal primordium, plus endoderm of urogenital sinus area called vaginal plate
vaginal plate changes into vagina how?: grows as a solid cylinder of endoderm, then spaces develop and fuse into common space.
remnant of vaginal plate is called?: hymen
condition if hymen not perforated?: hydrocolpos
problems caused if hymen not perforated: fills with fluid, compresses urethra, urine backs up, can cause hydronephrosis
indifferent stage of genital development lasts until?: about 9th week
names of the 5 indifferent genitalia swellings?: central anterior genital tubercle, two urogenital folds around urogenital sinus opening, labioscrotal swellings around urogenital folds.
If no male hormones present, genital tubercle forms: glans clitoris
if no male hormones present, urogenital folds form: labia minora
if no male hormones present, labioscrotal swellings form: labia majora
If male hormones present, genital tubercle: elongates, drawing urogenital folds with it
how is fissure created on ventral surface of glans: ingrowth of epithelium(ectoderm) forms glandular plate, which breaks down, creating the fissure
fusion of urogenital folds creates?: penile urethra
direction of fusion of folds, and result: posteriorÂ– anterior bringing urethral meatus out to glans
in male, labioscrotal swellings do?: migrate together and fuse to become scrotum
if urethra doesnÂ’t fuse properly?: hypospadias Â– urethral opening on underside of penis
what if body canÂ’t create cortisol?: ruins feedback loop that stimulates adrenal cortex
name of condition where body canÂ’t create cortisol: congenital virulizing adrenal hyperplasia
CVAH individuals are: genotypic females, phenotypic males: no breasts, small penis, chest hair, male pattern baldness
If cortisol not produced?: hypothalamus induces pituitary to release ACTH, asking adrenal glands to make cortisol. Ad. gland canÂ’t make cortisol, but makes instead lots of androgens, which have masculinizing effects
treatment for CVAH: give cortisol.
androgens do what: drive masculinization
cells take up testosterone how: testosterone binds to a receptor within target cell. Both enter nucleus. These change gene expression.
testosterone complex drives what changes at 8 wks: masculinization of mesonephric duct + tubules
at 10 weeks, what happens with testosterone: taken into target cells in urogenital sinus and converted to dihydrotestosterone.
testosterone converted to dihydrotestosterone by: steroid reductase enzyme
dihydrotestosterone does what: binds to receptor in target cell, enters nucleus, mediates changes to gene expression that masculinize indifferent genitalia
karyotype of Congenital virulizing Adrenal hypoplasia: XX (female)
gonads and ducts of CVAH: ovaries, and female ducts
External genitalia of CVAH: masculinizes due to androgens: male genitalia
gonadal dysgenesis: 46XX or 46 XY Â– usually only streak ovary, with uterus/uterine tubes. No testicle, leydig/testosterone, no male duct development: remain pre-pubertal female, with no functioning gonad
Androgen resistance syndrome (or androgen insensitivity syndrome): canÂ’t take up androgens, so no masculinizing takes place. Genetically male 46XY, but otherwise female: external genitalia, short vagina to nowhere, no pubic or axillary hair, ample breasts. no male ducts, no descent of testes.

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