∞ generated and posted on 2018.10.08 ∞

Female mammals are responsible for producing and maturing ova, obtaining sperm from males, becoming subsequently internally fertilized, and then physiologically supporting subsequent embryonic development as well as post-partum development.

Females in terms of their contribution to reproduction essentially by definition produce ova, which are produced, in animals, within gonads which we refer to as ovaries.

This page contains the following terms: Ovary, Follicle, Oogenesis, Ovulation, Ovum, Fallopian tube, Uterus, Cervix, Endometrium, Vagina, Vulva, Sexual response, Menstrual cycle, Ovarian cycle, Follicular phase, Luteal phase, Corpus luteum, Uterine cycle, Menses, Menstrual phase, Proliferation phase, Secretory phase

The above video is more than a bit overwhelming but does provide an overview of the female reproductive system through to the approximately the point of embryo implantation.


Female gonads.
The ovaries are the site of ovum formation. The latter occurs within ovarian follicles, or just 'follicles' for short.

The ovaries are found in the abdominal cavity and are important endocrine organs, producing estrogen and progesterone in varying amounts over the course of the menstrual cycle. The production of these hormones is considered explicitly in terms of discussion of both follicle development and what is known as the ovarian cycle.

Links to terms of possible interest: Broad ligament, Fallopian tube, Ovary, Uterus, Vagina

The above video walks through the anatomy and histology of the ovary.


Egg containing spherical clusters of cells where many of these clusters together make up ovaries.
The follicle is more precisely described as an ovarian follicle. During its maturation, it not only supports the formation of the ovum but also the production of estrogen, which stimulates the proliferation of the uterine lining.

Following release of a mature egg – the ovum, as occurs in the course of the process that is known as ovulation – the follicle is converted into what is known as a (or the) corpus luteum. The corpus luteum in turn is responsible for secreting progesterone during the secretory phase of the uterine cycle as well as the overlapping luteal phase of the ovarian cycle.

Note that it is follicle-stimulating hormone, i.e., FSH, as secreted by the anterior pituitary gland, that stimulates follicle maturation. It is a jump in luteinizing hormone (LH), also produced by the anterior pituitary gland but as stimulated by rising blood estrogen levels, that stimulates ovulation itself.

Links to terms of possible interest: Atretic follicle, Corpus albicans, Corpus luteum, Follicular cells, Follicular fluid, Graafian follicle, Ovary, Ovum, Primary follicle, Ruptured follicle, Secondary oocyte Stroma of ovary

The above video provides a nice discussion of both primordial follicles and primary follicles.

The above video provides a nice discussion of both primordial follicles and primary follicles.


Meiotic conversion of an oogonium to ovum.
This process takes place within ovarian follicles and spans from prior to birth through post ovulation. Oogonia give rise to primary oocytes which go through their first round of meiotic division to form what are known as secondary oocytes. This occurs prior to birth and primordial follicles, primary follicles, and secondary follicles all contain primary oocytes.

Secondary oocytes initiate the second round of meiosis within mature follicles a few hours prior to ovulation. This gives rise to the ovum, which is released upon ovulation. The second round of meiosis is not completed, however, until post fertilization, should fertilization occur.

Links to terms of possible interest: Corpus luteum, Diploid cell, Embryo, Haploid cell, Meiosis, Meiosis I, Meiosis II, Oogenesis, Oogonium, Ovary, Ovum, Polar body, Primary oocyte, Ruptured follicle, Secondary oocyte, Sperm,

The above video is a good diagramatical overview of oogenesis.


Gamete release from the female gonad.
Ovulation consists of release of an ovum – technically, a secondary oocyte – from an ovary. This allows for egg entrance into the fallopian tube along with subsequent exposure to sperm (if available) and potentially subsequent fertilization.

Ovulation also serves as the dividing line between the follicular phase and luteal phase of the ovarian cycle. It furthermore is associated with an increase in progesterone production as mediated by the corpus luteum, which forms from the formerly ovum-associated structure that is left behind in the ovary following ovum release.

Ovulation itself is stimulated by a peak in levels of follicle stimulating hormone (FSH) along with luteinizing hormone (LH), both of which are produced by the anterior pituitary gland.

Links to terms of possible interest: Corpus luteum, Follicle, Oocyte, Ovary, Ovulation

The above video discussed ovulation with nice graphics!


An unfertilized egg cell that is receptive to fertilization.
The above definition actually is technically wrong since the ovum, as a post-meiotic structure, doesn't exist in humans until post fertilization. In fact, it instead is a secondary oocyte that is released upon ovulation and which in fact is fertilized, with fertilization stimulating the completion of meiotic division (meiosis) and thereby ovum formation.

Nonetheless, the term ovum is used sufficiently often to describe the cell that is released in the course of ovulation that, for the sake of simplicity, we'll use that term as well. The ovum is, regardless, either fertilized, thereby generating the zygote (which then implants), or instead fails to be fertilized and consequently is lost.

Links to terms of possible interest: Ovum, Polar body

The above video shows the formation, release, and then fertilization of what at least loosely may be described as an ovum, with subsequent embryonic development of the fertilized egg through implantation depicted as well.

Fallopian tube

Connecting organ between the ovary and the uterus.
The fallopian tubes, also known as the uterine tubes, carry the unfertilized egg (that is, the ovum, or secondary oocyte) towards the uterus. They also are the sites of fertilization and thus also carry the fertilized egg, or zygote, towards the uterus. That movement is motivated via cilia lining these tubes, which pull the ovum from the abdominal cavity into the fallopian tube and then, as noted, direct movement via fluid flow towards the uterus.

Links to terms of possible interest: Blastocyst, Broad ligament, Cervix, Cleavage, Endometrium, External cervical orifice, Fallopian tube, Fertilized egg, Internal cervical orifice, Morula, Myometrium, Ovary, Ovulation, Uterus, Vagina, Zygote

This is a nice animation of a sperm swimming within a fallopian tube.


Location in mammals where fetus gestation occurs.
The uterus consists of what can be described as a "body" along with the cervix. The uterus, as a part of the female reproductive tract, otherwise is located between the vagina and the fallopian tubes, with the cervix serving as the partition between the uterus and the vagina.

The uterus possesses walls that are rich in smooth muscle (myometrium) and its lining, the endometrium, is the site of placental attachment. Sperm following ejaculation into the vagina passes through the cervix, into the uterus, and from there into the fallopian tubes.

Links to terms of possible interest: Bladder, Rectum, Urethra, Uterus, Vagina

The above video provides a guide to the histology of the uterus.

The above video provides an endoscopic view of the uterus; note that the tubal ostia are where the fallopian tubes enter into the uterus and the fundus is the top of the uterus.


Muscular canal separating the lumen of the uterus from that of the vagina.
It is the cervix that dilates during the dilation phase of parturition. That is, the cervix expands its opening sufficiently that movement of the baby out of the uterus becomes possible. It is also through the cervix that sperm must swim during its journey from the vagina into the uterus. It additionally is through the cervix that the shed uterine lining must flow during menses. Lastly, during pregnancy the uterus is sealed off from the vagina due to the formation of mucus plug within the cervix.

The cervix is not simply an opening but has depth, including what are known as an internal orifice (separating the cervical canal from the uterus) and an external orifice (separating the cervical canal from the vagina). In fact, the external orifice projects outward into the vagina.

Links to terms of possible interest: Bladder, Cervical canal, Cervical cancer, Cervix, External orifice, Fallopian tube, Fetus, Genital warts, HPV, Human papilloma virus, Internal orifice, Lumen, Menses, Mucus plug, Muscular, Oropharyngeal cancers, Ovary, Oxytocin, Pap smear, Parturition, Pelvic examination, Penis cancer, Posterior pituitary gland, Pregnancy, Rectum, Sperm, Uterine contractions, Uterine palpation, Uterus, Vagina

The above video walks through some of the anatomy and histology of the cervix.

The above video briefly discusses the cervix and then concentrates on cellular abnormalities particularly as potentially associated the cervical cancer.


The mucous membrane lining of the uterus.
It is the endometrium that partially dies and then which is partially shed over the course of the menstrual phase of the uterine cycle. This is not the function of the endometrium, however. The endometrium instead serves prior to shedding as the site of embryo along with placental attachment during pregnancy.

The endometrium prior to and following implantation, that is, attachment of the developing embryo, is thick and rich with blood vessels. Increasing thickness, richness in blood vessels, and indeed functionality is seen throughout the post-menstrual phase of the uterine cycle and through into pregnancy itself should that occur. This thickness and functionality, however, is reversed upon menses.

Introduction to the layers making up the uterus, with emphasis on the endometrium and the changes it goes through during the menstrual cycle.


Internal female structure directly involved in sexual intercourse and into which sperm is deposited in the course of male ejaculation.
The vagina also can be viewed as a canal that serves to connect the vulva, or external genitalia, with the cervix, i.e., the entrance to the uterus. A primary functional role of the vagina is to stimulate the erect penis towards the occurrence of ejaculation of sperm. This is accomplished in part as a consequence of supplying sufficient friction to stimulate the penis (as provided by various folds lining the vagina) while at the same time supplying sufficient lubrication to allow for relatively facile penal penetration into the vagina (lubrication as a supplied by mucus, as supplied in part by Bartholin's glands).

Having been deposited into the vagina, the sperm then must actively move through the adjacent cervical opening and into the uterus. In the course of parturition, i.e., the birthing process, the baby as well must pass through the vagina. Contrasting a caesarian section, this natural birthing process is referred to as a vaginal birth.

The vagina normally is not visible but instead is obscured by the relatively small diameter of the vaginal opening as found within the vaginal vestibule, that in turn is obscured by the overlying vulva.

Links to terms of possible interest: Anus, Bladder, Cervix, Fallopian tube, Ovary, Rectum, Urethra, Uterus, Vagina

Over the top, but a video on the vagina.


Female external genitalia.
The female external genitalia consist of the clitoris, numerous folds that can obscure to varying degrees the vaginal vestibule as well as the clitoris, and a fat-padded, hair-covered expanse of skin found above the clitoris that is known as the mons pubis.

The clitoris is an erectile organ and in fact a quite large organ, only a small portion of which (the glans) is found ventrally to the vaginal vestibule. This is a site of female sexual sensory stimulation. The glans of the clitoris can be fully or partially shrouded in a fold of skin known as the clitoral hood.

The vaginal vestibule otherwise is enclosed by the labia minora, which also consists of skin. Neither the clitoral hood nor the labia minora possess hair.

The labia majora, which are found laterally to the labia minora, and may or may not obscure the labia minora, by contrast typically does possess hair. The hair associated with labia majora as well as that associated with mons pubis become prominent over the course of puberty.

Note that the mons pubis is also found in males, the labia minora are equivalent embryologically in part to foreskin in males, the clitoris is equivalent to the penis itself, and the labia majora are equivalent to the skin making up the scrotum in males.

Links to terms of possible interest: Anus, Bulb of the vestibule, Clitoris, Corpus cavernosum, Crus clitoris, Glans clitoris, Labia minora, Labia majora, Mons pubis, Urethral orifice, Vagina, Vulva,

The above video is another less formal but still good introduction to the vulva, though with a fair amount of emphasis on the clitoris.

The above video is by a plastic surgeon so discusses not just female urogenital anatomy but how that can be modified surgically; nonetheless, it provides a good introduction to female urogenital anatomy, particularly the vulva.

The above video is a less formal but still good introduction to the vulva.

The above video also takes a less formal though pretty amazing look at the internal as well as external aspects of the vulva and other anatomy.

Sexual response

Excitement followed by plateau followed by orgasm followed by resolution.
Sexual response represents characteristic stages of sexual arousal. Four such stages exist. Excitement corresponds to arousal, particularly as occurs prior to the initiation of sexual intercourse or equivalent. The plateau phase takes place prior to orgasm and in terms of sexual intercourse corresponds to vaginal penetration by the penis along with associated stimulation of one by the other.

Orgasm differs between males and females and, with males, especially will typically correspond to a not readily reversed transition away from the plateau phase. With males also it is ejaculation of semen that occurs during the orgasm phase.

Resolution is post orgasmic and corresponds to a substantial reduction in sexual excitement as well as a period of refraction (most notable again in males) during which subsequent organism is impossible.

Links to terms of possible interest: Erection, Excitement phase Orgasmic phase, Plateau phase, Resolution phase, Vaginal lubrication

This is a cute but also informative look at the human sexual response.

This video walks us through the human sexual response, with emphasis on orgasm.

The above video provides an overview of sex, fertilization, and contraception; discussion of fertilization begins at 3:06; discussion of contraception begins at 6:58.

Menstrual cycle

Period over which ovulation, fertilization, and potential implantation occurs in great apes.
A combination of what are known as the ovarian cycle and uterine cycle together make up the menstrual cycle. These cycles begin and end with menses or instead, deviating from the cycle, begin with menses and end with pregnancy.

Various hormones produced by a combination of the ovaries and anterior pituitary gland drive the cycle. This includes follicle stimulating hormone (FSH) as produced by the anterior pituitary, estrogen production by the resultantly developing follicle, luteinizing hormone (LH) as produced by the anterior pituitary and as stimulated by increasing estrogen levels, and progesterone along with estrogen as produced by the corpus luteum of the ovary.

Links to terms of possible interest: Corpus albicans, Corpus luteum, Estradiol, Follicular phase, Follicle, Follicle-stimulating hormone, Luteal phase, Luteinizing hormone, Ovarian cycle, Ovulation, Progesterone, Uterine cycle

The above video provides a nice overview of the physiology of the menstrual cycle.

The above video is crude but makes its points well in terms of what's going on in the menstrual cycle, including what happens if pregnancy should occur.

Ovarian cycle

Well defined sequence of modifications to the egg-producing anatomy of sexually mature but not pregnant females.
The ovarian cycle, a component of the menstrual cycle, is associated with the preparation for fertilization rather than associated with the pregnancy that follows such fertilization. Its purpose is to prepare the egg for fertilization as well as prepare the body more generally, via hormone secretion, for subsequent embryonic development.

The ovarian cycle is associated with changes in the levels of the hormones estrogen and progesterone which are produced by the ovaries, and follicle stimulating hormone (FSH) along with luteinizing hormone (LH) which are both produced by the anterior pituitary gland. The overall process can be differentiated into follicular phase and luteal phase.

Links to terms of possible interest: Androgens, Anterior pituitary gland, Corpus luteum, Egg, Embryonic development, Estrogen, Fertilization, Follicle stimulating hormone, Follicular phase, FSH, Hypothalamus, Inhibin, LH, LH surge, Luteal phase, Mature follicle, Menstrual cycle, Ovarian cycle, Ovaries, Ovulated secondary oocyte, Positive feedback, Pregnancy, Pregnant, Progesterone, Ruptured follicle, Sexually mature, Thecal cells,

Follicular phase

Stage during ovarian cycle leading up to ovulation.
During the follicular stage of the ovarian cycle the follicles mature and oogenesis is reinitiated. This phase of the ovarian cycle is strongly under the influence of follicle-stimulating hormone (FSH) as well as luteinizing hormone (LH) and estrogen production strongly dominates over progesterone production. Under the influence of estrogen, the endometrium also is regenerated (proliferative phase of the uterine cycle).

Links to terms of possible interest: Estrogen, Follicular phase, Luteal phase, Menstrual phase, Progesterone, Proliferative phase, Secretory phase

The above video takes us through the ovarian cycle, beginning with the follicular phase and ending with the luteal phase, with substantial emphasis on the roles of hormones along with their impact on each other's production.

Luteal phase

Stage during ovarian cycle following ovulation.
The luteal phase is dominated by the presence and actions of the corpus luteum. During this phase, levels of both estrogen and progesterone are high, with both produced by the corpus luteum. Also during this phase the endometrium fully matures in anticipation of implantation.

Should implantation fail to occur, then the corpus luteum degenerates and the luteal phase transitions back into the follicular phase, with the start of menses providing the dividing line. Should implantation successfully occur, however, then the corpus luteum will be sustained, maintaining the endometrium through the earlier stages of pregnancy.

Links to terms of possible interest: Corpus luteum, Follicle, Follicular phase, Luteal phase, Ovarian cycle, Ovulation,

The above video is a reasonably detailed overview of the menstrual cycle.

Corpus luteum

Progesterone-secreting structure that is present within ovaries during the secretory phase of the ovarian cycle.
The ovarian cycle consists of a follicular phase that is followed by a luteal phase. The follicular phase is associated with follicle development and maturation of its associated egg. Estrogen is secreted by the follicle, resulting in stimulation of a buildup of the endometrium.

Estrogen production peaks and then declines in association with egg release from the follicle. The follicle then matures into the corpus luteum, which produces progesterone (as well as smaller amounts of estrogen) that in turn both sustains and further prepares the endometrium for subsequent embryo implantation.

Absent implantation and subsequent pregnancy, the corpus luteum is no longer sustained but instead is reabsorbed. This loss corresponds to substantial declines in progesterone levels of the blood, leading to death and then shedding of the cells making up the outer layers of the endometrium, i.e., as associated with the menstrual phase of the uterine cycle.

Links to terms of possible interest: Atresia, Atretic follicles, Corpus luteum, Cortex, Egg, Endometrium, Estrogen, Follicle, Follicular phase, Implantation, Granulosa lutein cells, Luteal phase, Medulla, Menstrual phase, Ovarian cycle, Ovary, Ovulation, Ovum, Progesterone, Secreted, Secretory phase, Theca lutein cells, Uterine lining

The above video discusses the corpus luteum and its formation.

Uterine cycle

Well defined sequence of modifications to the embryo-nourishing anatomy of sexually mature but not pregnant female mammals.
The uterine cycle, a component of the menstrual cycle, is associated with preparation for embryo implantation and thus support of subsequent pregnancy. The overall process can be differentiated into a menstrual phase, proliferative phase, and then secretory phase during which characteristic changes take place in both the ovaries (and developing egg) and uterus (particularly its lining).

These phases are driven by hormone secretion by the ovaries, estrogen and progesterone, over the course of the ovarian cycle. Primarily affected by those hormones is the endometrium, i.e., the uterine lining, which is shed and then regenerated over the course of the uterine cycle.

Links to terms of possible interest: Anatomy, Egg, Embryo, Endometrium, Estrogen, Menstrual cycle, Ovarian hormones, Ovarian cycle, Ovaries, Progesterone, Pregnant, Proliferative phase, Secretory phase, Sexually mature, Uterine cycle, Uterine lining

The above video provides a nice overview of the uterine cycle.


Bloody discharge from the vagina associated with shedding of the endometrium.
Menses, or menstruation, occurs during the menstrual phase of what is known as the uterine cycle. It serves as a visual indication both of lack of pregnancy and of impending fertility.

In humans, menses begins approximately every 28 days during a female's fertile years. Menopause is associated with the cessation of periodic menstruation.

Menstruation is also lacking prior to puberty, during pregnancy, and often also during breastfeeding. The latter is not necessarily 100% associated with a lack of fertility as ovulation will occur prior to onset of the first menses following pregnancy.

Links to terms of possible interest: Breastfeeding, Cervix, Endometrium, Menopause, Menses, Menstrual phase, Menstruation, Ovulation, Pregnancy, Puberty, Uterine cycle, Uterus, Vagina

The above video considers the overall context of menses.

Menstrual phase

Time during the uterine cycle of endometrium shedding.
It is during the menstrual phase of the uterine cycle that menses, that is, menstruation occurs. This occurs in response to the loss of progesterone production by the now also lost corpus luteum. This loss occurs following a failure of the occurrence of early embryo implantation into the uterine lining. Following that failure the now proliferated endometrium is discarded, resulting in cell death and shedding into and then out through the vagina.

Links to terms of possible interest: Basilar zone of endometrium, Cervix, Corpus luteum, Early embryo, Endometrial glands, Endometrium, Functional zone of endometrium, Implantation, Menses, Menstrual cycle, Menstrual phase, Menstruation, Myometrium, Perimetrium, Progesterone, Proliferative phase, Secretory phase, Uterine cavity, Uterine lining, Vagina

The above video first considers the menstrual phase as a part of the menstrual cycle and then transitions into talking about menses more generally, from a medical perspective.

Proliferation phase

Time during the uterine cycle of endometrium regeneration.
It is during the proliferative phase that the endometrium proliferates from its shed state as found at the end of the menstrual phase. The endometrium is not completely shed during the menstrual phase so it is from the underlying remaining layers that proliferation occurs. This proliferation is stimulated by increasing estrogen secretion by the maturing follicle.

The above video discusses the histology of proliferative phase endometrium.

Secretory phase

Time during the uterine cycle when the corpus luteum is producing progesterone.
It is during the secretory phase that the endometrium becomes receptive to implantation by the early embryo. It is also the secretory phase that is terminated should implantation fail to occur, thereby giving rise to the menstrual phase.

The above video discusses the histology of secretory phase endometrium.