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Again, ovarian follicles are oocytes and their supporting cells. They grow and develop in a process called folliculogenesis    , which typically leads to ovulation of one follicle approximately every 28 days, along with death to multiple other follicles. The death of ovarian follicles is called atresia, and can occur at any point during follicular development. Recall that, a female infant at birth will have one to two million oocytes within her ovarian follicles, and that this number declines throughout life until menopause, when no follicles remain. As you’ll see next, follicles progress from primordial, to primary, to secondary and tertiary stages prior to ovulation—with the oocyte inside the follicle remaining as a primary oocyte until right before ovulation.

Folliculogenesis begins with follicles in a resting state. These small primordial follicles    are present in newborn females and are the prevailing follicle type in the adult ovary ( [link] ). Primordial follicles have only a single flat layer of support cells, called granulosa cells    , that surround the oocyte, and they can stay in this resting state for years—some until right before menopause.

After puberty, a few primordial follicles will respond to a recruitment signal each day, and will join a pool of immature growing follicles called primary follicles    . Primary follicles start with a single layer of granulosa cells, but the granulosa cells then become active and transition from a flat or squamous shape to a rounded, cuboidal shape as they increase in size and proliferate. As the granulosa cells divide, the follicles—now called secondary follicles    (see [link] )—increase in diameter, adding a new outer layer of connective tissue, blood vessels, and theca cells    —cells that work with the granulosa cells to produce estrogens.

Within the growing secondary follicle, the primary oocyte now secretes a thin acellular membrane called the zona pellucida that will play a critical role in fertilization. A thick fluid, called follicular fluid, that has formed between the granulosa cells also begins to collect into one large pool, or antrum    . Follicles in which the antrum has become large and fully formed are considered tertiary follicles    (or antral follicles). Several follicles reach the tertiary stage at the same time, and most of these will undergo atresia. The one that does not die will continue to grow and develop until ovulation, when it will expel its secondary oocyte surrounded by several layers of granulosa cells from the ovary. Keep in mind that most follicles don’t make it to this point. In fact, roughly 99 percent of the follicles in the ovary will undergo atresia, which can occur at any stage of folliculogenesis.


This multipart figure shows how follicles are generated. The top panel shows the six stages of folliculogenesis. In each stage, the major cell types are labeled. The bottom part shows a micrograph of a secondary follicle and the major parts are labeled.
(a) The maturation of a follicle is shown in a clockwise direction proceeding from the primordial follicles. FSH stimulates the growth of a tertiary follicle, and LH stimulates the production of estrogen by granulosa and theca cells. Once the follicle is mature, it ruptures and releases the oocyte. Cells remaining in the follicle then develop into the corpus luteum. (b) In this electron micrograph of a secondary follicle, the oocyte, theca cells (thecae folliculi), and developing antrum are clearly visible. EM × 1100. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Questions & Answers

list down all the hormones secreted by adrenal gland
Odong Reply
The amount of blood pumped by the left ventricle of the heart in one contraction.
Javid Reply
how we can calculate the cardiac output
and how do we calculate the strock valume
stroke volume is not all the blood contained in the left ventricle; normally, only about two-thirds of the blood in the ventricle is expelled with each beat.
Cardiac output 5.5 l S. V 68.75 ml H. R 80bpm
If we consider SV 70, end systolic vol is about 15% of total(approx always) out of a total of 80-85 ml only 70ml is pumped per systole
what is macrophages?and its function
Sajjad Reply
macrophages they are white blood cells that engulf dead cells in the body
what is power stroke?
no idea
what is the stroke volume of heart?
If an autoimmune disorder targets the alpha cells, production of which hormone would be directly affected?
Samantha Reply
what is a muscle?
Gideon Reply
A band or bundle of fibrous tissue in a human or animal body that has the ability to contract, producing movement in or maintaining the position of parts of the body
what's endolphthamities and panophthalmities?
fluid around the brain
louise Reply
what ?
cerebro spinal fluid
The brain and spinal cord are surrounded by a clear fluid called cerebrospinal fluid (CSF). This fluid is produced and stored in cavities in the brain called ventricles. It circulatesaround the brain, moving from ventricle to ventricle. ... Hydrocephalus is a condition in which there is too much CSF
what is hydrocphalus
aminul Reply
Google krlena na madarchod yha maa chudwa rha ha sabko notification bhjke
when cerebrospinal fluid produce în the brain, i.e. brain ventricles, is to abundent in the brain and is not trăind out of the brain. as a consequence this lichid pute mechanical pressure oñ the brain and it pushes the cerebrum tissue. as a consequence this pressure on the neuronscan cause neurologi
cal disfunctions, for example clinical headache
. It is posible to drainout the fluid through a device dalles shunt,as i remember.
but where are also home medicinsfor decreasing the production of cerebrospin.fluid etc
there are some medicines that can decrease the production of csf
a neurologist advice is needed
i wrote some medicines NOT home medicines. it is a serious condition and specialized medical advice is needed. of course also general medical knowledge may be helpful, but not enough, a specialist is neede
if anyone help me in physiology
Radika Reply
i am BSN student of first year which book is best for physiology
i am BSN student of first year which book is best for physiology
ross and wilson anotomy and physiology
it's 1 book for anotomy and physiology it's best for bs nursing
yes Ross and wilson physiology is better for study
I'm also the student of bs nursing
I study guiton and hall &ganong
I'm also midwif help me be the best book for midwif
what ia the function of indocrine system
salam all friend
help me with this question; explain at least five emergency acute pain found in fundamental emergency medicine
Fascial compartment of forearm
what's a tissue?
Mwape Reply
a group of cells with the same function
tissue is a group of cells that perform the same functions.
explain a bit about a tissue
A tissue is made up of cells that are similar in shape and perform the same function, for instance brain cells form up a brain tissue. Whereas a group of tissues that perform the same function form an organ... so in this case the brain which is the organ is formed as a result of brain tissues.
what is gross anatomy
the branch of anatomy that deals with the structure of organs and tissues that are visible to the naked eye.
1.To know how the structures functions. 2.To easily identify the micro structures and the macro structures. 3.To be able to explain that anatomy is the study of the structures and physiology is the study of how the structures functions
Abban Reply
Describe the two classes of hormones (3 with subclasses) and how they affect their target cells.
Shalaeha Reply
what is control centre
Gohil Reply
Angie The larger air passage of the lung is
Angie Reply
guys help to make me understand the structure of the skin
Olokojo Reply
the skin has three layers epidermis,dermis,and subcutaneous tissue
guys what is esrf
End Stage of Renal Failure
what's the meaning of OPD
Out Patient Department
the skin has the assesory structures.that is, sebaceous glands, sweat glands, hairs, nails,blood vessels and lymph vessels.
define cell and give it's brief description of the orgenelles
Manish Reply
a cell is a basic unit of life
what about philosophy
the organelle is a membrane bound structure in the cell that performs a particular function
Cell.Is a basic functional unit of life. it has the organelles, Golgi apparatus, smooth endoplasmic membrane, rough endoplasmic reticular,Lysosomes, mitochondrial and others.

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