Week 9 - Reproductive system anatomy

pelvic diaphragm separates the….

pelvis from the perineum

muscle of pelvic diaphragm and its structure (5)

levator ani

3 layers and an opening for pelic viscera

Puborectalis forms sling around rectum -> helps with faecal continence

Pubococcygeus

Iliococcygeus

divisions of pelvic diaphragm and contents (2)

anal triangle posteriorly → contains anal aperture

urogenital triangle anteriorly → contains urogenital hiatus

perineal membrane location and structures formed (3)

superficial to pelvic diaphragm and covers urogenital triangle only

forms opening for urethra in both males and females

forms vagina fo females

deep perineal pouch - location and composition

space above perineal membrane and below levator ani

contains skeletal msucle that forms sphincters around urethra (external urethral sphincter) and vagina (sphincter urethrovaginalis)

damage to pelvic floor structures during childbirth (3)

levator ani and pernieal membrane can be injured during birth

puborectalis and pubococcygeus support urethra vagina and rectum in females → urinary stress incontinence, prolapse of uterus, faecal incontinence

muscles in deep perinela pouch can also be involved

ovary location

adjacent to lateral wall of pelvis in peritoneal cavitiy and posterior to broad ligament

attached to uterus by ligament of ovary

ovarian blood supply and nerves

ovarian artery from descending aorta

medulla = supply of nerves and blood vessels within ovary

divisions of ovary (2)

1. ovarian cortex → lcoation of folliculogenesis

2. ovarian surface epithelium → outer epithelial linding

folliculogenesis - steps (6)

1. Before birth, somatic cells will go between germ cells and break them up to form primordial cells -> oocytes surrounded with flat granulosa cells

2. Each menstrual cycle: a number of primordial follicles activated and undergo folliculogenesis to form primary follicles

   • Flat granulosa cells change into cuboidal granulosa cells

   • Oocyte grows in size

3. Granulosa cells proliferate to form multiple layers around the oocyte and recruit theca cells -> secondary/ preantral follicles

4. Continued proliferation of granulosa cells forms a fluid-filled cavity -> antrum

5. Continued growth of antrum leads to oocyte surrounded by cumulus cells with mural granulosa cells forming the other layer -> pre-ovulatory/ graphian follicle

6. Ovulation of the oocyte with some of the cumulus cells leaves the remaining granulosa cells and theca cells to form corpus luteum

structure of uterus (2)

thick-walled muscular organ

inner lining = endometrium

location and orientation of uterus

best supported at cervix -> opens inferiorly into posterior wall of vagina

When bladder is empty: uterus = anteverted (AV) relative to vagina and anteflexed (AF) over bladder

function of uterus (2)

facilitates development of embryo

supports pregnnancy and sheds during menstrual cycle

connection between ovaries and uterus

uterine tubes → pair of muscular tubes that project laterally to connect ovaries to uterus

opens adjacanet to ovaries

structure of uterine tubes (3)

Infundibulum = funnel shaped with fimbriae -> facilitates collection of oocytes

Ampulla = relatively large labyrinthine lumen for fertilization -> implantation usually in body of uterus

Isthmus = narrow portion that connects to uterus

vagina location (2)

muscular passage connecting uterine cavity to exterior

posterior to urethra and anterior to rectum

female peritoneum summary (2)

Folds over the top of the pelvic viscera

comes together over uterine tubes to form broad ligament

female peritoneum - ligaments (3)

Main peritoneal folds = round ligament of uterus and broad ligament

Ligament of ovary = formed by folds over ovarian vessels

female peritoneum - pouches (2)

Peritoneum projects in between bladder ad uterus to form vesico-uterine pouch

Peritoneum folds over uterus and between uterus and rectum to form recto-uterine pouch

signifance of pouches formed by female peritoneum

when fluid accumulates in peritoneal cavity, collect by lieing on back and letting it collect in recto-uterine pouch → syringe through posterior part of vaginal fornix to aspirate fluid

female external genitalia - undifferentiate to differentiated

genital tubercle → glans clitoris

urogenital fold → lavia minora

lavioscrotal fold → labia majora

superficial structure of female external genitalia

Vulva/ pudendum = erectile tissues and overlying skin

Labia minora = two skin folds next to midline -> comes together anteriorly to form gland clitoris

Vestibule = area between labia minora -> contains openings for urethra and vagina

Labia majora = larger skin folds lateral to labia minora

attachment anchors for roots of female external genitalia

perineal membrane and pubic arch

corpora cavernosa attaches to pubic arch

erectile tissues of female external genitalia (5)

2 corpora cavernosa

2 bulbs of vestibule -> continuous with Gland clitoris

Glans clitoris -> anterior to urethra and not covered by skin

muscles of external female genitalia (2)

Ischiocavernosus muscles = cover attached parts of corpora cavernosa to maintain erection of clitoris

Bulbospongiosus muscles = cover bulbs of vestibule and greater vestibular gland

function of bulbospongiosus muscle (3)

Support pelvic floor

Assist in erection of clitoris

Compress greater vestibular gland

strcuture of testes (3)

Divided into ~250 lobules by connective tissue septa -> each lobule contains 3-10 seminiferous tubules -> each tubule forms highly convoluted loop within lobule

Tubules end as straight tubule at mediastinum -> tubules erectus

Connected to rete testis -> anastomosing channel system

difference between embryogenesis and spermatogenesis

spermatogenesis involves true stem cell can self renew and differentiate to produce sperm cell -> located at periphery of the seminiferous epithelium

embryogenesis stops after birth

spetamtogenesis - steps (4)

1. Primordial germ cell under goes mitosis to produce spermatogonium -> becomes primary spermatocyte

2. Secondary spermatocyte after meiotic division I

3. Spermatids after meiotic division II

4. Elongated spermatids once tail elongates -> enters lumen

layers around testis (2)

Tunica vaginalis = extension of abdominal peritoneum during descent

Tunica albuginea = dense connective tissue capsule

gonadal devleopment in males

Testes descends along posterior abdominal wall towards inguinal canal by 7 months gestation

Through inguinal canal and into scrotum just before birth -> drags blood vessels, nerves, duct system (vas deferens) and layers of abdominal wall into scrotum

cryptorchidism - def and consequences (4)

undescended testes

Histological changes -> infertility

Increased risk of testicular cancer

Needs to be surgically corrected -> preferentially before 18 months to 2 years age

epididymis - structure (3)

5m long, highly coiled tube

Consists of caput (head), corpus (body) and caudal (tail) segments

Surrounded by smooth muscle cells

function of epididymis

storage and maturation of sperm → acquire ability to move

vans-deferens - fucntion

Transports spermazoa to ejaculatory duct -> ejaculation mediated by SNS

location of vas deferens (3)

penetrates abdominal wall through inguinal canal and descend along lateral wall of pelvic cavity to meet duct of seminal vesicle -> forms ejaculatory duct

Muscular duct -> smooth muscle wall

Part of spermatic cord

vasectomy

ligation of vans deferens to prevent sperm from reaching penis

accessory glands of male reproductive system (3)

contribute to volume of ejaculate

Seminal vesicles

Prostate

Bulbourethral glands

location of seminal vesicles (2)

Posterior surface of bladder

Ducts of seminal vesicles join vas deferens to form ejaculatory duct -> empties into prostatic urethra

function of seminal vesicles (2)

Contributes to volume of semen, sperm motility and sperm viability

Secretes alkaline viscous fluid -> neutralises acidic female reproductive tract environment

location of prostate (4)

Inferior to bladder

anterior to rectum

superior to pelvic diaphragm

surrounds urethra

fucntions of prostate as a secretory gland (3)

Secretion = watery liquid containing zinc, citric acid, prostaglandins and proteolytic enzymes

section is slightly acidic but alkaline secretion from seminal vesicles makes semen overall alkaline

Prostate specific antigen (component of secretion) liquifies semen to help movement of sperm -> often upregulated in prostate cancer

fucntions of prostate as a muscle (3)

helps move seminal fluid into urethra

functions of prostate as a valve

ensures right fluid flow during right time → urination or ejaculation

common diseases associated with prostate (2)

1. benign prostatic hypertropy → occurs mostly in elderly men

• hypertrophy compresses urethra and can eventually completely block it → DRE reveals bulky prostate

2. prostate cancer → common malignancy in men

• diagnosed by blood tests + DRE reveals rock hard prostate

• treated with radiotherapy, chemotherapy or removal

bulbourethral glands - structure and location

Paired, pea shaped gland in deep perineal pouch

Duct opens into spongey urethra

function of bulbourethral glands

mucous type secretion acts to lubricate urethra → forms pre-ejaculate

peritoneal pouches in males

Rectal vesical pouch = fold that goes between rectum and bladder

no uterus so only one pouch

external genitalia development - males vs females summary

testosterone production by testes = strcutures grow to be much bigger in males than females

undifferentiate to differentiated external genitalia - males vs females (3)

Genital tubercle becomes glans penis -> homologous to glans clitoris

Urogenital fold fuses proximal to distal to form penis shaft -> homologous to labia minora

Labioscrotal fold fuses in the midline to form to the scrotum -> homologous to labia majora

hypospadias - def

congenital disorder of the penis -> urethra opens somewhere along the shaft of the penis

Occurs in ~1:250 boys at birth -> increasing trend

erectile tissue in male external genitalia (4)

covered by skin

Body of penis = pendulous and entirely surrounded by skin

Scrotum = homologous to labia majora -> skin fuses to midlines to form raphe and testes descends into pouch

Skin over glans penis = prepuce -> opens anteriorly and is attached to glans at frenulum

attachment points for roots of penis (2)

perineal membrane and pubic arch

erectile tissues in males vs females

male erectile tissues have two corpora cavernosa and a single corpus spongiosum

females have two corpora cavernosa as well but two bulbs of vestibule and no corpus spongiosum

superficial structure of penis (2)

Corpus spongiosum expands distally to form glans penis

Urethra pierces perineal membrane -> enters corpus spongiosum and opens at glans penis

male erection - cause

mediated by PNS -> relaxes arteries in penis to allow blood to fill erectile tissues

Ischiocavernosus and bulbospongiosus muscles move blood from root into body of penis and constricts venous drainage