Ovarian follicle
An ovarian follicle (also known as a Graafian follicle in its mature state) is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cells and contains a single oocyte.
On this page:
Gross anatomy
An ovarian follicle can be initiated to grow and develop, culminating in ovulation of usually a single competent oocyte in humans. Approximately 10 ovarian follicles begin to mature during a normal menstrual cycle and out of these usually one will turn into a dominant ovarian follicle.
During ovulation, the primary follicle forms the secondary follicle and then the mature vesicular follicle. After rupture, the follicle turns into a corpus luteum and eventually involutes to the corpus albicans.
Radiographic features
Ultrasound
Following maturations under the development of gonadotropins, small follicles can be seen as small sonolucent rounded structures around the ovary. In the normal physiological state one of the follicles enlarges to ~1 cm to become a dominant follicle which grows further to ~2.5 cm 1. This is then called an ovarian follicular cyst.
See the 1-2-3 rule.
MRI
Ovarian follicles, as well as follicular cysts, may be seen as rounded structures around the ovary.
Signal characteristics
- T2: high signal (as with many fluid-filled entities)
History and etymology
It is named after Reinier de Graaf, Dutch physician and anatomist (1641-1673).
Related Radiopaedia articles
Anatomy: Abdominopelvic
- skeleton of the abdomen and pelvis
- muscles of the abdomen and pelvis
- spaces of the abdomen and pelvis
- anterior abdominal wall
- posterior abdominal wall
- abdominal cavity
- pelvic cavity
- perineum
- abdominal and pelvic viscera
- gastrointestinal tract
- spleen
- hepatobiliary system
-
endocrine system
-
adrenal gland
- adrenal vessels
- chromaffin cells
- variants
- pancreas
- organs of Zuckerkandl
-
adrenal gland
-
urinary system
-
kidney
- renal pelvis
- renal sinus
- avascular plane of Brodel
-
variants
- number
- fusion
- location
- shape
- ureter
- urinary bladder
- urethra
- embryology
-
kidney
- male reproductive system
-
female reproductive system
- vulva
- vagina
- uterus
- Fallopian tubes
- ovaries
- broad ligament (mnemonic)
- variant anatomy
- embryology
- blood supply of the abdomen and pelvis
- arteries
-
abdominal aorta
- inferior phrenic artery
- celiac artery
- superior mesenteric artery
- middle suprarenal artery
- renal artery (variant anatomy)
- gonadal artery (ovarian artery | testicular artery)
- inferior mesenteric artery
- lumbar arteries
- median sacral artery
-
common iliac artery
- external iliac artery
-
internal iliac artery (mnemonic)
- anterior division
- posterior division (mnemonic)
- variant anatomy
-
abdominal aorta
- portal venous system
- veins
- anastomoses
- arterioarterial anastomoses
- portal-systemic venous collateral pathways
- watershed areas
- arteries
- lymphatics
- innervation of the abdomen and pelvis
- lumbar plexus
-
sacral plexus
- lumbosacral trunk
- sciatic nerve
- superior gluteal nerve
- inferior gluteal nerve
- nerve to piriformis
- perforating cutaneous nerve
- posterior femoral cutaneous nerve
- parasympathetic pelvic splanchnic nerves
- pudendal nerve
- nerve to quadratus femoris and inferior gemellus muscles
- nerve to internal obturator and superior gemellus muscles