Download 5. Anatomy and Embryology

Chapter 5. Anatomy and
Embryology
부산백병원 산부인과
R3 강영미
Pelvic Viscera
Embryonic development

Female urinary and genital tract
 Closely related, anatomically and embryologically
 Embryologic urinary system ; important inductive
influence on developing genital system
 Anomalies in one system are often mirrored by
anomalies 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
excretory 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 in 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
differentiation 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 embryo
Signal for differentiation of Leydig cells from the
surrounding mesenchyme
Male fetus

Leydig cells
 Produce testosterone,dihydrotestosterone with 5areductase


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 Skene) 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 gonads
(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 other
In the latter case, a fallopian tube and single uterine horn
may 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
gender
Caused either by abnormal levels of sex hormones or
abnormalities 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
sacrum
 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 ant. wall
∵ vagina is attached at a higher point posteriorly than
anteriorly
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 cavity 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 receives 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 anterior to the vagina
Lined by nonkeratinized squamous epithelium that is
responsive to estrogen stimulation
Contains as inner longitudinal layer and outer circular
layer
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
transversus abdominis muscle
Like peritoneum, divided into a parietal and a visceral
component

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
tuberosities 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)