chapter 5. anatomy and embryology 부산백병원 산부인과 r3 강영미
TRANSCRIPT
Chapter 5. Anatomy and Embryology
부산백병원 산부인과R3 강영미
Pelvic Viscera
Embryonic development
Female urinary and genital tract Closely related, anatomically and embryologically Embryologic urinary system ; important inductive influe
nce on developing genital system Anomalies in one system are often mirrored by anomal
ies in another system
Embryonic development
Urinary system, internal reproductive organs and external genitalia Develop synchronously
at an early embryologic age(table 5.6)
Urinary system
Kidney, Renal collecting system, Ureters
Kidney, renal collecting system and ureters from longitudinal mass of mesoderm(nephrogenic cord)
Mesonephric(Wolffian) duct
Singular importance for the following reasons Grows caudally in developing embryo to open an excre
tory channel into the primitive cloaca and outside world
Serves as starting point for development of the metanephros which becomes definitive kidney
Differentiates into the sexual duct system in male Although regressing in female fetuses, inductive role i
n development of the paramesonephric or mullerian duct
Metanephros
Development of metanephros
그림 13-8
Bladder and Urethra
Cloaca
Genital system development
Genital system
In embryologic stage, early genital system Indistinguishable between two sexes Known as “ indifferent stage” of genital development Mesodermal epithelium, mesenchyme and primordial
germ cell
Internal reproductive organs
Primordial germ cells
1. Mullerian duct
Paramesonephric or mullerian ducts Form lateral to mesonephric ducts Grow caudally and then medially to fuse in midline Contact urogenital sinus in region of the post. urethra
at slight thickening known as sinusal tubercle
Male fetus
TDF Results in degeneration of gonadal cortex and differen
tiation of the medullary region of the gonad into Sertoli cells
Sertoli cells Secrete glycoprotein known as anti-mullerian hormone
(AMH) Cause regression of paramesonephric duct system in male e
mbryo Signal for differentiation of Leydig cells from the surrounding
mesenchyme
Male fetus
Leydig cells Produce testosterone,dihydrotestosterone with 5a-red
uctase Testosterone
Responsible for evolution of mesonephric duct system into vas deferens, epididymis, ejaculatory ducts and seminal vesicle
At puberty, leads to spermatogenesis and changes in primary and secondary sex characteristics
DHT Results in development of the male external genitalia and
prostate and bulbourethral glands
Female fetus
In the absence of TDF, medulla regresses and cortical sex cords break up into isolated cell clusters(primordial follicles)
in the absence of AMH & testosterone, Mesonephric duct system degenerates Then, paramesonephric duct system develops
Inf. fused portion Uterovaginal canal -> uterus and upper vagina
Cranial unfused portions Open into celomic cavity(future peritoneal cavity) Fallopian tubes
3. Accessory genital glands
Female accessory genital glands Develop as outgrowths from urethra(paraurethral or Sk
ene) and definitive urogenital sinus(greater vestibular or Bartholin)
Ovaries first develop in the thoracic region, but arrive in pelvis by complicated process of descent This descent by differential growth ; under the control
of a ligamentous cord called the gubernaculum
Genital system ; 3. Accessory genital glands Gubernaculum
External genitalia
Genital system abnormalities
Congenital defects in sexual development, usually arising from a variety of chromosomal abnormalities, tend to present clinically with ambiguous external genitalia
Known as intersex conditions or hermaphroditism Classified according to the histologic appearance of the g
onads
(1) True hermaphroditism
Individuals with true hermaphroditism Have both ovarian and testicular tissue
Most commonly as composite ovotestes Occasionally with an ovary on one side and a testis on the oth
er In the latter case, a fallopian tube and single uterine horn ma
y develop on the side with the ovary
∵ absence of local AMH Extremely rare condition
(2) Pseudohermaphroditism
In individuals with pseudohermaphroditism, Genetic sex indicates one gender External genitalia has characteristics of the other gend
er Caused either by abnormal levels of sex hormones or abn
ormalities in the sex hormone receptors
(2) Pseudohermaphroditism
Males with pseudohermaphroditism Genetic males with feminized external genitalia
Hypospadias(urethral opening on the ventral surface of the penis)
Incomplete fusion of the urogenital or labioscrotal folds ; m/c manifesting sx.
Females with pseudohermaphroditism Genetic females with virilized external genitalia
Clitoral hypertrophy Some degree of fusion of the urogenital or labioscrotal folds
Genital Structures
Vagina
Hollow fibromuscular tube extending from the vulvar vestibule to the uterus In dorsal lithotomy, directed posteriorly toward the sac
rum In upright position, almost horizontal Spaces between the cervix and vagina ; ant, post, and
lateral vaginal fornices Post. vaginal wall ; about 3 cm longer than the a
nt. wall ∵ vagina is attached at a higher point posteriorly than ant
eriorly
Vagina
Post. vaginal wall ; separated from post. cul-de-sac and peritoneal cavity by the vaginal wall and peritoneum
This proximity ; clinically useful Culdocentesis
Intraperitoneal hemorrhage, pus, other intraabdominal fluid Posterior colpotomy
As an adjunct to laparoscopic excision of adnexal masses
Cervix
Endocervical canal About 2-3cm in length, opens proximally into the endometrial cavi
ty at the internal os In early childhood, during pregnancy, or with oral contraceptive use,
Columnar epithelium may extend from the endocervical canal onto the exocervix -> eversion or ectopy
Cervical mucus production Under hormonal influence Around the time of ovulation - profuse, clear, thin In the postovulatory phase of the cycle ; scant and thick mucus
Corpus
At birth, cervix and corpus are about equal in size In adult women, corpus has grown to 2-3 times
the size of the cervix Position ; flexion and version
Flexion - angle between the long axis of the uterine corpus and cervix
Version - angel of the junction of the uterus with the upper vagina
Corpus
Divided into several different regions ; Isthmus or lower uterine segment
The area where the endocervical canal opens into the endometrial cavity
Uterine cornu On each side of the upper uterine body, funnel-shaped area r
eceives the insertion of the fallopian tubes Fundus
Uterus above this area(cornu)
Fallopian tubes
Fallopian tubes and ovaries ; referred to as the adnexa Vary in length from 7 to 12 cm Function
Ovum pickup Provision of physical environment for conception Transport and nourishment of the fertilized ovum
Fallopian tubes
Divided into several regions ; Interstitial
Narrowest portion of the tube, lies within the uterine wall and forms the tubal ostia at the endometrial cavity
Isthmus Narrow segment closest to the uterine wall
Ampulla Larger diameter segment lateral to the isthmus
Fimbria(infundibulum) Funnel-shaped abdominal ostia of the tubes
Ovaries
Paired gonadal structures that lie suspended between the plevic wall and the uterus by the infundibulopelvic ligament laterally and uteroovarian ligament medially
Varies in size with measurements up to 5*3*3cm Consists of a cortex and medulla
Cortex - specialized stroma and follicles Medulla - primarily of fibromuscular tissue and blood vessels
Urinary tract
Ureters
25cm in length Totally retroperitoneal in location Pathway of lower half of each ureter
Traverses the pelvis after crossing the common iliac vessels at their bifurcation, just medial to the ovarian vessels
Descends into the pelvis adherent to the peritoneum of the lateral pelvic wall and the medial leaf of the broad ligament
Enter the bladder base anterior to the upper vagina, traveling obliquely through the bladder wall
P. 772
Bladder
divided into two areas ; Base of the bladder
Consists of the urinary trigone posteriorly and a thickened area of detrusor anteriorly
Trigone - two ureteral orifices and opening of the urethra into the bladder
Receives a-adrenergic sympathetic innervation Is the area responsible for maintaining continence
Dome of the bladder Parasympathetic innervation Is responsible for micturition
Urethra
Female urethra ; about 3 to 4 cm in length Extends from the bladder to the vestibule, traveling just a
nterior to the vagina Lined by nonkeratinized squamous epithelium that is res
ponsive to estrogen stimulation Contains as inner longitudinal layer and outer circular lay
er
Abdominal Wall
Abdominal wall
1. Skin 2. Muscles
Five muscles and their aponeuroses(fig 5.16)
3. Fascia ; (1) Superficial fascia
Consists of two layers Camper fascia
Most superficial layer, which contains a variable amount of fat Scarpa fascia
Deeper membranous layer continuous in the perineum with colles fascia(superficial perineal fascia) and with deep fascia of the thigh(fascia lata)
3. Fascia ; (2) Rectus sheath
Aponeuroses of the external and internal oblique and the transversus abdominis
; Combine to form a sheath for the rectus abdominis and pyramidalis, fusing medially in the midline at the linea alba and laterally at the semilunar line(fig 5.16)
3. Fascia ; (3) Transversalis fascia and endopelvic fascia Firm membranous sheet on the internal surface of the tra
nsversus abdominis muscle Like peritoneum, divided into a parietal and a visceral co
mponent Transversalis fascia
Continues along blood vessels and other structures leaving and entering the abdominopelvic cavity
Contributes to the formation of the visceral (endopelvic) pelvic fascia
Pelvic fascia Invests the pelvic organs and attaches them to the pelvic side
walls, thereby playing a critical role in pelvic support
Perineum
Situated at the lower end of the trunk between the buttocks
Its bony boundaries Lower margin of the pubic symphysis anteriorly Tip of the coccyx posteriorly Ischial tuberosities laterally
Diamond shape of the perineum Divided by imaginary line joining the ischial tuberositie
s immediately in front of the anus, at the level of the perineal body, into an ant. urogenital and a post. anal triangle(fig 5.18)