In this section, we will examine the physiological processes that occur within the male and female reproductive systems. These processes are male sperm production (spermatogenesis), and the female ovarian and uterine cycles. Spermatogenesis Males create 1,500 sperm per second, and the process continues throughout the adult life span. This process, known as spermatogenesis occurs in the seminiferous tubules within the testes. The Sertoli cells within the seminiferous tubules support sperm development. Once the sperm are fully mature, they enter the seminiferous tubules and pass their way to the epididymis, where they travel through the epididymis and mature into fully functional sperm. This process takes about 20 days, and then the sperm are stored in the tail of the epididymis until ejaculation.  Ruiz Villarreal, M. (2006). Complete diagram of a human spermatozoa [Ilustration]. Wikimedia Commons. https://en.wikipedia.org/wiki/Sperm#/media/File:Complete_diagram_of_a_human_spermatozoa_en.svg Sperm Anatomy The head of the sperm contains the nucleus which houses the DNA or chromosomes. Capping the head of the sperm is a structure called the acrosome that contains the enzymes to help penetrate the egg during fertilization. The midpiece of the sperm contains the mitochondria that supplies the sperm with ATP to be able to propel the tail to move through the female reproductive tract. Finally, the tail of the sperm is the flagellum that beats like a whip to propel and move the sperm forward and enables it to move through the reproductive tract of the female. We will examine the physiology of fertilization in our next module. Ovarian and Uterine Cycles Female reproductive physiology is more complex, as it involves coordinating two cycles: the ovarian cycle and the uterine cycle. The ovarian cycle regulates egg development. The uterine cycle regulates endometrium development within the uterus. The cycles occur at the same time in a 21-40-day range; the most typical range is 28 days. Females are born with approximately 1 million oocytes, of which only 300-500 will develop to the point of ovulation. The ovarian cycle occurs in the ovaries, and consists of follicle and oocyte maturation, ovulation, and development of the corpus luteum. The ovarian cycle consists of two phases, the follicular phase and the luteal phase.  The Follicular Phase The follicular phase lasts from day 1-14 of the 28-day cycle; during this phase, a dominant follicle matures and secretes large amounts of estrogen. Ovulation of this follicle’s mature oocyte will occur on day 14. Ovulation is the process by which the egg leaves an ovary to enter into the fallopian tubes. At this transition point, remaining granulosa cells form the corpus luteum as the cycle transitions to the luteal phase. This luteal phase lasts from day 14-28 and involves the activity of the corpus luteum. The corpus luteum secretes progesterone, which influences endometrial lining development in the ute ...

1. In this section, we will examine the physiological processes that
occur within the male and female reproductive systems. These
processes are male sperm production (spermatogenesis), and the
female ovarian and uterine cycles.
Spermatogenesis
Males create 1,500 sperm per second, and the process continues
throughout the adult life span. This process, known as
spermatogenesis occurs in the seminiferous tubules within the
testes. The Sertoli cells within the seminiferous tubules support
sperm development. Once the sperm are fully mature, they enter
the seminiferous tubules and pass their way to the epididymis,
where they travel through the epididymis and mature into fully
functional sperm. This process takes about 20 days, and then the
sperm are stored in the tail of the epididymis until ejaculation.
Ruiz Villarreal, M. (2006). Complete diagram of a human
spermatozoa [Ilustration]. Wikimedia Commons.
https://en.wikipedia.org/wiki/Sperm#/media/File:Complete_diag
ram_of_a_human_spermatozoa_en.svg
Sperm Anatomy
The head of the sperm contains the nucleus which houses the
DNA or chromosomes. Capping the head of the sperm is a
structure called the acrosome that contains the enzymes to help
penetrate the egg during fertilization. The midpiece of the
sperm contains the mitochondria that supplies the sperm with
ATP to be able to propel the tail to move through the female
reproductive tract. Finally, the tail of the sperm is the flagellum
that beats like a whip to propel and move the sperm forward and
enables it to move through the reproductive tract of the

2. female. We will examine the physiology of fertilization in our
next module.
Ovarian and Uterine Cycles
Female reproductive physiology is more complex, as it involves
coordinating two cycles: the ovarian cycle and the uterine cycle.
The ovarian cycle regulates egg development. The uterine cycle
regulates endometrium development within the uterus. The
cycles occur at the same time in a 21-40-day range; the most
typical range is 28 days.
Females are born with approximately 1 million oocytes, of
which only 300-500 will develop to the point of ovulation. The
ovarian cycle occurs in the ovaries, and consists of follicle and
oocyte maturation, ovulation, and development of the corpus
luteum. The ovarian cycle consists of two phases, the follicular
phase and the luteal phase.
The Follicular Phase
The follicular phase lasts from day 1-14 of the 28-day cycle;
during this phase, a dominant follicle matures and secretes large
amounts of estrogen. Ovulation of this follicle’s mature oocyte
will occur on day 14. Ovulation is the process by which the egg
leaves an ovary to enter into the fallopian tubes. At this
transition point, remaining granulosa cells form the corpus
luteum as the cycle transitions to the luteal phase. This luteal
phase lasts from day 14-28 and involves the activity of the
corpus luteum. The corpus luteum secretes progesterone, which
influences endometrial lining development in the uterus.
This ovarian cycle is coordinated with the uterine cycle, which
pertains to the events that occur within the uterus. Most of the
uterine changes involve thickening of the endometrium to
prepare to receive a potentially fertilized egg, and shedding of

3. this lining through menstruation as the alternative. The uterine
cycle is divided into three phases: menstrual phase, proliferative
phase, and secretory phase.
The Menstrual Phase
Days 1-5 of the 28-day cycle are termed the menstrual phase, as
the endometrium is discharged through the vagina. At this point,
the controlling hormones of estrogen and progesterone are at
their lowest. After this period, estrogen begins to rise, and the
endometrium rebuilds to prepare to receive a potentially
fertilized egg. At day 14, progesterone from the corpus luteum
begins to rise, which leads to thickening of the endometrium. If
the egg is not fertilized, the corpus luteum breakdown (as part
of the ovarian cycle) leads to endometrial decomposition as the
uterine cycle re-enters into the menstrual phase.
Menstrual cycle [Illustration]. (2009). Wikimedia commons.
https://commons.wikimedia.org/wiki/File:MenstrualCycle2_en.s
vg
The Endocrine System’s Hormonal Regulation
Both of these cycles are under the endocrine system’s hormonal
regulation. The hypothalamus secretes gonadotropin releasing
hormone, which signals the anterior pituitary’s release of
follicle stimulating hormone (FSH) and luteinizing hormone
(LH). These regulate the ovaries’ estrogen production, which
sends a feedback loop to the hypothalamus to maintain
homeostasis.
Encyclopedia Brittanica. (2016). Female reproductive system
[Illustration]. Britannica ImageQuest.
https://go.openathens.net/redirector/rasmussen.edu?url=https%3
A%2F%2Fquest-eb-

4. com.eu1.proxy.openathens.net%2Fsearch%2Ffemale-
reproductive-system%2F1%2F309_1156355% 2FFemale-
reproductive-system
Now that we have examined the physiology of the reproductive
systems, check your understanding with the cases and activities
that follow.
Males and females both have primary reproductive organs called
gonads, and secondary reproductive organs (ducts, glands, and
external genitalia). Yet, particularly after puberty, male and
female differences emerge. In this section, we will examine the
anatomical elements of both the male and reproductive systems.
Male Reproductive Organs
The male reproductive organs include primary sex organs
(gonads) called testes, as well as secondary organs. Secondary
organs include the scrotum, male duct system, penis, and
glands. The three major male reproductive accessory glands are
the prostate, seminal vesicles, and bulbourethral glands.
Encyclopedia Britannica. (2016). Male reproductive system
[Illustration]. Britannica ImageQuest.
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A%2F%2Fquest-eb-
com.eu1.proxy.openathens.net%2Fsearch%2Fmale-reproductive-
system%2F1%2F309_365517%2FMale-reproductive-
system%2Fmore
Testicles
The primary sex organs, testicles, come in a pair; they are made
up of hundreds of seminiferous tubules which produce sperm.

5. The seminiferous tubules transport sperm to the epididymis. The
two types of cells within the seminiferous tubules are the germ
cells, which mature into sperm, and the Sertoli cells, which
support sperm development. Additional endocrine cells, Leydig
cells, lie outside the seminiferous tubules. The Leydig cells
produce testosterone.
Openstax. (2013). Testicle anatomy [Illustration]. Wikimedia
Commons.
https://en.wikipedia.org/wiki/Testicle#/media/File:Figure_28_0
1_03.JPG
The testicles’ surface is covered by a tunica albuginea, and then
the scrotum. The scrotum’s location outside the abdominal
cavity is critical for temperature regulation, as sperm require a
temperature slightly lower than body temperature. The scrotum
contains muscles and blood vessels to fine-tune temperature
regulation.
· The dartos muscle can wrinkle the scrotum’s surface, therefore
decreasing its surface area to promote heat retention.
· The cremaster muscle elevates the testes, and can serve to
promote heat retention in cold conditions.
· The pampiniform venous plexus can, conversely, cool
incoming blood due to its location surrounding the testicular
artery.
Openstax. (2013). Musculature and inner workers of the scrotum
[Illustration]. Wikimedia Commons.
https://upload.wikimedia.org/wikipedia/commons/5/53/Figure_2
8_01_02.JPG

6. Each testicle’s posterior side contains a 20-foot coiled cord-like
structure called the epididymis. The epididymis is where sperm
cells mature. They take 20 days to pass through the epididymis.
To exit the body, the sperm pass through additional ducts:
ductus deferens (also called the vas deferens), the ejaculatory
duct, and the urethra (which is shared with urine). The penis
encases the ducts.
Sperm
Sperm make up only 10% of ejaculation, as male accessory
glands create additional fluids to comprise seaman. Seminal
vesicles secrete yellowish fructose-based alkaline liquids that
comprise 60% of the semen volume. This fluid enhances sperm
mobility within the female’s reproductive tract. The prostate
secretion is a milky white substance that comprises 30% of the
semen volume; it is nutrient-rich to support the sperm. The
bulbourethral glands produce a small amount of additional clear
fluid for lubrication.
Male anatomy [Illustration]. (2003). Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Male_anatomy.png
Female Reproductive Anatomy
Like males, females have both internal and external
reproductive anatomy. Internal female anatomical instructions
include ovaries, ovarian tubes (also called fallopian tubes), the
uterus, and the vagina. Externally, females have a clitoris and
labia.
Typical sites for pelvic inflammatory disease [Illustration].
(2014). Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Male_anatomy.png

7. Ovaries
The female primary sex organs (gonads) are called ovaries.
They produce both eggs and sex hormones (progesterone and
estrogen). The two ovaries are quite small, each being roughly
the size of two almonds. They are not free-floating, as many
ligaments support them. These ligaments include the ovarian
ligament, suspensory ligament, broad ligament, and
mesovarium.
Ovaries contain immature eggs (oocytes), each of which is
surrounded by supporting granulosa cells and a follicle. Each
month, one of these follicles is ovulated into a fallopian tube
connected to the uterus.
The Uterus
The uterus is largely made of smooth muscle located between
the bladder and rectum. Like kidneys, the uterus has three
regions and three layers. The three regions are the fundus, body,
and cervix. The three layers, from superficial to deep are the
perimetrium, myometrium, and endometrium.
Encyclopedia Britannica. (2016). Female reproductive system
[Illustration]. Britannica ImageQuest.
https://go.openathens.net/redirector/rasmussen.edu?url=https%3
A%2F%2Fquest-eb-
com.eu1.proxy.openathens.net%2Fsearch%2Ffemale-
reproductive-system%2F1%2F309_1156355%2FFemale-
reproductive-system
The Vagina
The uterus leads to the vagina. The vagina is located between

8. the rectum and bladder. It serves as a pathway for intercourse,
menstruation, and the birthing process. In the next section, we
will examine the menstrual process in further detail.