A&P II REPRODUCTIVE SYSTEM STUDY GUIDE

Give examples of homologous reproductive structures in males and females

male testes & female ovaries

male penis & female clitoris

Describe the Hypothalamic-pituitary-gonadal axis?

Production of gametes and sex hormones is regulated by sequence
of hormonal events involving hypothalamus, anterior pituitary gland, and testes 

Involves interacting hormones: GnRH, FSH, LH, sex hormones,
and inhibin

Define meiosis. Compare and contrast meiosis to mitosis

Meiosis – unique kind of nuclear division that occurs only in gonads. Reduces number of chromosomes in gametes by half so
zygote does not end up with twice as many chromosomes. introduces genetic diversity, as all daughter cells are genetically
different from original cell
▪ Random alignment of homologous pairs provides variability
▪ Crossing over increases variability

mitosis  – Results in identical daughter cells
– Ensures that all cells in body have same complement of DNA for
normal growth and repair

Describe the structure and function of the testes and explain the importance of their location in the
scrotum.

sperm-producing male gonads that lie within the scrotum.

the scrotum provides a cool controlled environment required for healthy sperm development and overall reproductive health. 

Describe the location and function of the seminiferous tubules

found in the lobules of each testis. function as the site of sperm production.

Describe the location, structural characteristics, and function of the epididymis

made up of the head, body and tail. made of smooth muscle

found on the lateral side of each testis, resting along its posterior boarder within the scrotal sac.

responsible for the final maturation of sperm, permitting mobility for them. 

Describe the roles of the male accessory glands

seminal glands - Produces viscous alkaline seminal fluid
▪ Fructose (energy source for sperm motility), citric acid,
coagulating enzyme, and prostaglandins (induce sperm motility,
peristalsis in uterus)
▪ Yellow pigment fluoresces with UV light
▪ Comprises 70% volume of semen

prostate - Encircles urethra inferior to bladder
– Consists of smooth muscle that contracts during ejaculation
– Secretes milky, slightly acid fluid
▪ Contains citrate, enzymes, and prostate-specific antigen (PSA)
▪ Plays a role in sperm activation

bulbourethral glands - Pea-sized glands inferior to prostate
– Produce thick, clear mucus during sexual arousal
▪ Lubricate glans penis
▪ Neutralize traces of acidic urine in urethra

Discuss the sources and functions of semen.

it is a milky white mixture of sperm and accessory gland secretions.

protects and activates sperm and facilitates sperm movement.

Where do mitosis and meiosis occur in the process of
spermatogenesis?

both occur in the seminiferous tubules of the testis .

mitosis - in the basal layer

meiosis - when diploid spermatocytes enter the adluminal compartment of the seminiferous tubules.

Describe the location and functions of cells associated with the seminiferous tubules (sustenocytes,
spermatogenic cells, myoid cells, interstitial endocrine cells, and function of each)

Sustentocytes - large columnar cells act as supporting cells and
play role in sperm formation

Spermatogenic cells - cells that are surrounded by
sustentocytes and give rise to sperm

Myoid cells - smooth muscle-like cells surrounding seminiferous
tubule that contract to squeeze sperm and testicular fluid through tubules

Interstitial endocrine cells - (Leydig cells) produce androgens
and some estrogen

Which cells/structures maintain the blood testis barrier? What is its function?

tight junctions . 

Prevents sperm antigens from escaping into blood and causing
activation of immune system

Describe the functions of the major regions of sperm.

head - genetic region that includes nucleus and helmetlike acrosome containing hydrolytic enzymes that enable sperm to penetrate egg

mid piece - metabolic region containing mitochondria that
produce ATP to move tail

Tail - locomotor region that includes flagellum

Describe the role of FSH and LH in spermatogenesis/ testosterone production

FSH stimulates spermatogenesis indirectly by stimulating
sustentocytes to release androgen-binding protein (ABP)

LH binds to interstitial endocrine cells, prodding them to
secrete testosterone

what are the physiological
effects of testosterone on male reproductive anatomy

development, maturation and maintenance 

Describe the function of the ovaries

Produce female gametes (ova)
– Secrete female sex hormones, estrogen and progesterone

Describe the function of the fallopian tubes

site of fertilization. receive ovulated oocyte.

What is the function of fimbriae? Where does
fertilization occur?

stiffen and sweep ovarian surface creating current to
carry oocyte into tube

Describe the layers (composition) of the uterine wall

Perimetrium - outermost serous layer (visceral peritoneum)

Myometrium - bulky middle layer consisting of interlacing layers of
smooth muscle; Contracts rhythmically during childbirth

Endometrium - mucosal lining. 

has two layers:
– Stratum functionalis (functional layer) - Changes in response
to ovarian hormone cycles
• Shed during menstruation
– Stratum basalis (basal layer) - Stem cells in this layer form
new stratum functionalis after menstruation
• Unresponsive to ovarian hormones

What is the function of the myometrium?

produces powerful contractions during labor

Which layer becomes shed during menstrual cycle?

stratum functionalis of endometrium

Which layer of the uterine wall contains stem cells and what is their function?

stratum basalts of endometrium. to form new stratum functionalis after menstration

In which layer of the uterine wall does the embryo implant?

endometrium

Describe the process of oogenesis and compare it to spermatogenesis.

Three key differences between oogenesis and spermatogenesis:
– 1. Production of primary oocytes occurs only fetus
– 2. In primary oocytes, meiosis is arrested in late prophase I and
resumes only years later (if at all)
– 3. In secondary oocytes, meiosis is arrested in metaphase II and is
only completed if fertilization occurs

Oogenesis: production of female gametes. It starts with diploid oogonia that undergo mitosis during fetal development to produce primary oocytes, which immediately enter meiosis I but arrest at prophase I. These primary oocytes remain arrested until puberty.

spermatogenesis : the continuous production of sperm beginning at puberty. spermatogonia divide mitotically to produce primary spermatocytes, which enter meiosis I and produce secondary spermatocytes.

Describe the stages of follicle development

Primordial follicle - single layer of squamous pre-granulosa cells surrounding
primary oocyte

Primary follicles - have a single layer of cuboidal pre-granulosa cells surrounding
primary oocyte

Secondary follicles -
have multiple layers of granulosa cells surrounding
primary oocyte

Vesicular (antral) follicles - 

(tertiary follicles) have a fluid-filled cavity called an
antrum
– Before ovulation primary oocyte inside vesicular follicle resumes meiosis and
becomes secondary oocyte

relate the stages of follicle development to oogenesis 

Primordial follicles are first follicles to develop in fetus
– At any given time, majority of ovarian follicles in woman are dormant
(inactive) primordial follicles

Primary oocytes are arrested in prophase I
– oocyte grows and granulosa cells become cuboidal and proliferate into multiple layers. The zona pellucida forms around the oocyte. Meiosis I is still arrested.

Secondary Follicle

• The follicle develops a fluid-filled space called the antrum. Theca cells differentiate into theca interna and externa. The oocyte increases in size, still meiosis I arrested. Granulosa cells and the theca produce estrogen.

tertiary (Antral/Preovulatory) Follicle

• The antrum enlarges, granulosa cells express receptors for FSH and LH, making the follicle hormone-responsive. The primary oocyte completes meiosis I just before ovulation, producing a secondary oocyte arrested at metaphase II.

what are the two possible fates of follicles

Atresia & Ovulation

Define atresia and ovulation

Atresia: apoptosis (programmed cell death) of oocyte and surrounding
cells
▪ Fate of 99.9% of all follicles
▪ Before puberty all recruited follicles undergo atresia

Ovulation: Each month after puberty, high levels of FSH rescues few
follicles (about 20) from atresia
▪ One follicle from this group is “selected” each month to become
dominant follicle and achieve ovulation

Describe the ovarian cycle phases. Which oocyte stage becomes ovulated

monthly (~28 day) series of events associated with
maturation of egg
– Two consecutive phases, with ovulation occurring midcycle
between phases

▪ Follicular phase: period of vesicular follicle growth
(days 1–14)

Ovulation : serge in luteinizing hormone that triggers release of mature egg from dominant follicle into Fallopian tube

▪ Luteal phase: period of corpus luteum activity (days 14–28)

the secondary oocyte becomes ovulated, which is ARRESTED in METAPHASE 11 of MEIOSIS

Which hormones regulate the ovarian cycle

Gonadotropin-releasing hormone (GnRH)

Follicle-stimulating hormone (FSH)

Luteinizing hormone (LH)

Estrogen

Progesterone

What is the role of thecal and granulosa cells in the follicular phase of the ovarian cycle

where does negative and positive feedback on the hypothalamus occur

anterior pituitary gland

Which hormones are implicated in
these negative feedback loops.

progesterone, estrogen, LH, and FSH

What causes the LH surge?

sustained high level of estrogen

Describe the effects of the LH surge on
oocyte and follicle.

triggers primary oocyte to complete meiosis I to
become secondary oocyte
– Secondary oocyte then enters meiosis II, continuing on to
metaphase II

LH transforms ruptured follicle into corpus luteum
– LH stimulates corpus luteum to secrete progesterone and some
estrogen almost immediately

What is the function of the corpus luteum?

secrete progesterone

what are the three phases of the uterine (menstrual) cycle

Days 0-4 : menstrual phase
Days 5–14: proliferative (preovulatory) phase

Days 15–28: secretory (postovulatory) phase

what happens at the Days 0–4: menstrual phase

Ovarian hormones are at lowest levels
▪ Stratum functionalis detaches from uterine wall and is shed
– Menstrual flow of blood and tissue lasts 3–5 days
▪ By day 4, growing ovarian follicles start to produce more estrogen

what happens at the Days 5–14: proliferative (preovulatory) phase

Rising estrogen levels prompt generation of new stratum
functionalis layer
– As layer thickens, glands enlarge, and spiral arteries increase
in number
▪ Estrogen also increases synthesis of progesterone receptors in
endometrium
▪ Thins out normally thick, sticky cervical mucus to facilitate sperm
passage
▪ Ovulation occurs at end of proliferative phase on day 14

what happens at the Days 15–28: secretory (postovulatory) phase

Phase that is most consistent in duration
▪ Endometrium prepares for embryo to implant
▪ Rising progesterone levels from corpus luteum prompt:
– Functional layer to become a secretory mucosa
– Endometrial glands to enlarge and secrete nutrients into
uterine cavity
– Thickened mucus to form cervical mucus plug that blocks
entry of more sperm, pathogens, or debris

Fluctuation of which hormones is
responsible for the changes in the endometrium?

estrogen and progesterone

The endometrial changes of the uterine cycle are coordinated with the phases of the ovarian cycle.
Understand which uterine phases overlap with the ovarian follicular and luteal phase

The follicular phase of the ovarian cycle overlaps with the menstrual and proliferative phases of the uterine cycle.

The luteal phase of the ovarian cycle (days ~15 to 28) overlaps with the secretory phase of the uterine cycle.

how do the levels of estrogen & progesterone change during the menstural phase?

Both estrogen and progesterone levels are low due to degeneration of the corpus luteum if fertilization does not occur. The low hormone levels cause the functional layer of the endometrium to shed, resulting in menstrual bleeding.

how do the levels of estrogen & progesterone change during the proliferative phase 

Estrogen levels rise as the ovarian follicles mature during the follicular phase. Estrogen stimulates the regeneration and thickening of the endometrial lining, promoting cell proliferation, vascularization, and rebuilding of the glands in the endometrium. Progesterone remains low in this phase

how do the levels of estrogen & progesterone change during ovulation

Estrogen peaks, triggering the LH surge and ovulation. Progesterone begins to rise as the corpus luteum forms

how do the levels of estrogen & progesterone change during the secretory phase (post ovulation)

Progesterone levels rise significantly, produced by the corpus luteum during the luteal phase. Progesterone transforms the endometrium into a secretory lining, increasing glandular secretion of nutrients such as glycogen and enhancing spiral artery growth to prepare the uterus for possible implantation. Estrogen is present at moderate levels, supporting the secretory changes.

Describe the effects of estrogen and progesterone on the endometrium

estrogen promotes the regeneration and thickening of the endometrial lining after menstruation. progesterone transforms the proliferative endometrium into a mature secretory lining afterwards.

they both orchestrate the cyclical remodeling of the endometrium.