week 9: female reproductive system

gonads

ovaries

• located in pelvic cavity on lateral side of uterus

• connected to body wall by ligaments → continuous with peritoneum

histology: surface (germinal) epithelium

layer of cuboidal cells → modified visceral peritoneum lacking CT

histology: tunica albuginea

dense CT

histology: ovarian cortex 

contains ovarian follicles and CT

histology: ovarian medulla

contains blood and lymph vessels, verves, CT

uterine/fallopian tubes: infundibulum

suspended over each ovary

• opens into peritoneal cavity

• fimbriae that cover the ovary during ovulation → help capture and over ovulated 2degree oocyte into uterine tube

fimbriae

finger like projections

uterine/fallopian tubes: ampulla

middle

• site where fertilization usually occurs

uterine/fallopian tubes: isthmus

connects to the uteru

uterine/fallopian tubes | histology: mucosa

simple columnar epithelium 

• ciliated cells: moves oocyte/zygote/morula along the uterine tube 

• non-ciliated secretory cells with microvilli: nourish oocyte/cell mass 

uterine/fallopian tubes | histology: muscularis externa

smooth muscle

• contractions aid oocyte/cell mass movement along the tube

uterine/fallopian tubes | histology: serosa

visceral peritoneum

uterus/womb 

hollow, muscular organ located superior to the bladder formed of the: 

• fundus: superior to the uterine tubes 

• body: forms the majority of the uterus 

  • contains the uterine cavity → site of embryo implantation and fetal growth occur

• cervix: inferior, narrow passafe that opens to the vagina

uterus histology: endometrium

mucus membrane

• formed of simple columnar epithelium (deep layer) + underlying highly vascular lamina propria layer 

uterus endometrium: stratum functionalis  

develops at puberty and is shed monthly → menstruation 

• contains endometrial glands → secrete nutritive fluid for the embryo prior to implantation 

uterus endometrium: stratum basalis

permanent layer

uterus histology: myometrium

muscularis externa → smooth muscle

uterus histology: perimetrium 

serosa → visceral peritoneum 

vagina histology: mucosa

thick stratified squamous epithelium and CT

• folded into numerous transverse ridges → rugae

vagina histology: muscularis externa

smooth muscle

• stretches during intercourse + birth

vagina histology: adventitia 

fibroelastic CT 

vulva

reproductive structures external to the vagina 

vulva: mons pubis

layer of adipose tissue that overlies and cushions the pubic symphysis

vulva: labia majora

large outer skin folds that surround the labia minora

vulva: labia minora

small inner skin folds that surround the vestibule

vulva: vestibule

contains the vaginal opening and external urethral orifice

• underlying greater vestibular glands secrete mucus that lubricates the vestibule

vulva: clitoris

derived from the same embryonic tissue as the penis

• mainly internal with small external portion visible at anterior junction of the labia minora → contains erectile tissue

follicle development: late embryonic + fetal period

• germ cells migrate to developing gonads → diff into oogonia + proliferate → mitosis doesn’t occur following this stage

• oogonia begin to diff into 1deg oocytes during early fetal period

  • single layer of flat pre-granulosa/follicular cells forms around = primordial follicles

• meiosis 1 begins, stops in P1

  • meiotic arrest until puberty

follicle development: childhood

absence of reproductive hormones renders ovary largely functionally inactive

follicle development | puberty: step 1

ovarian cycles begin

• reproductive hormones stimulate 1000 primordial follicles to develop within cortex each cycle

  • oocytes enlarge and follicular cells transition into cuboidal granulosa cells = 1deg follicles

follicle development | puberty: step 2

• granulosa cells of some 1deg proliferate = become stratified = 2deg follicles

  • secrete estrogen and fluids

  • theca cells (endo) also form around each follicle 

follicle development | puberty: step 3

fluid-filled spaces unite into single large antrum

• forms vesicular (antral) follicles

follicle development | puberty: step 4

fluid accumulates within a single dominant preovulatory (graafian) follicle 

• oocyte becomes isolated, is still surround by layer of granulosa cells → corona radiata 

• follicle grows in size and begins to protrude from the surface of ovary  

follicle development | puberty: step 5

just prior to ovulation, hormone levels stimulate meiosis1 to re-initiate forming 2deg oocyte 

• arrests in metaphase2

follicle development | puberty: step 6

follicle, in ovary, fills with blood + clots

• granulosa + theca cells proliferate forming corpus luteum → secretes high levels of hormones that support fetal development

follicle development | puberty: step 7 

corpus luteum degenerates into scar-like corpus albicans within 2 (no pregnancy) or 10 (with pregnancy) weeks 

• if no pregnancy, blood hormone levels initiate another cycle → approx. 500 in reproductive lifetime