Unit 17: Reproductive Systems Flashcards
(26 cards)
What are the structures of the reproductive systems?
- Gonads (testes/ovaries) - produce gametes and hormones
- Ducts - transport and store gametes
- Accessory glands - produce secretions that support the gametes
Info about the testes (gonads)
Located w/in the scrotum (skin and CT). Surrounded by 2 layers (tunics):
a) tunica vaginalis = outer (superficial) layer; serous
membrane derived from peritoneum
b) tunica albuginea = inner fibrous CT capsule; extends
inward to divided testis into lobules (small lobes)
Each lobule contains:
a) seminiferous tubules
- produce sperm (spermatogenesis)
- tubules unite to form rete testis on posterior side of each
testis (rete = network)
- walls of the tubules are composed of:
i. spermatogenic cells - germ cells in various stages of
development that will become sperm
ii. sustentocytes (nurse) cells = really just structural
support
- surround, nourish, and protect developing gametes
- extend from basement membrane to lumen
- are connected to one another by tight junctions that
form the blood-testis barrier - protects developing
sperm from immune system, toxins, and drugs
- produce testicular fluid - for sperm transport in tubule
lumen
b) Interstitial endocrine (Leydig) cells
- in CT btw. seminiferous tubules
- secrete testosterone (hormone)
Info about ducts (sperm)
Sperm formed in the seminiferous tubules enter the rete testis, and then move into a series of DUCTS:
a) epididymis
- posterior border of testis
- site of sperm storage and maturation (develop ability to
swim)
b) Vas (ductus) deferens
- transports sperm from the epididymis during ejaculation
- part of the spermatic cord, which carries the vas
deferens, nerves, blood supply, and lymphatic vessels
through the body wall
- enters anterior pelvic cavity and loops over posterior wall
of bladder
c) Ejaculatory Duct
- formed by union of vas deferens and duct from seminal
vesicle
d) Urethra
- transports urine and semen out of the body
- 3 regions:
i. prostatic urethra - runs through prostate gland
ii. intermediate (membranous) urethra - runs through the
urogenital diaphragm (muscular floor of pelvis)
iii. spongy (penile) urethra - runs through the corpus
spongiosum of the penis and ends at an opening at
the tip of the glans penis called the external urethral
orifice
Info about the penis
Urinary and copulatory organ. Parts:
a) Root
b) Body (shaft)
c) Glans penis (enlarged tip)
- has 3 cylindrical bodies of erectile tissue (blood sinuses
bound by CT):
a) 2 corpora cavernosa - dorsal/posterior (in the erect
position)
- form most of the root and shaft
b) 1 corpus spongiosum - midventral/anterior (in the erect
position)
- surround urethra and forms the glans penis
Info about male accessory glands
Contribute secretions during sexual arousal. About 95% of semen comes from the following glands, listen in order of highest to lowest contribution:
a) seminal vesicles (2)
- posterior to bladder
- secrete a fluid that provides sperm w/ a source of
nutrients
b) prostate gland (1)
- inferior to bladder and encircles prostatic urethra
- secretes a fluid that nourishes and activates sperm
motility
c) bulbourethral glands (2)
- below prostate in urogenital diaphragm (in contact /
external urethal sphincter)
- secretes thick mucus that helps lubricate the urethra and
the glans penis
What is spermatogenesis?
= sperm production w/in the seminiferous tubules
*see chart on pg. 3 to memorize
What is spermiogenesis?
Spermiogenesis (a part of spermatogenesis) is the differentiation of the spermatids into sperm:
- develop flagella and acrosomes
- lose most cytoplasm
What is spermatozoa structure?
1) Head
- nucleus (23 chrome.s [n])
- top of nucleus is covered by the acrosome = a modified lysosome that contains enzymes required to penetrate secondary oocyte
2) Body (midpiece)
- contains a large number of mitochondria that produce the ATP required for movement
3) Tail = flagellum
- propel sperm
- made of microtubules
What is semen?
Semen = sperm and testicular fluid (5%), and accessory gland secretions (95%).
- 2-5 ml released during ejaculation - contains 20-150 million sperm/ml
- pH is slightly alkaline = 7.2-7.6
- provides sperm w/ transportation medium, nutrients, and protection
What are the structures of the ovarian reproductive system specifically?
- gonads = ovaries, uterine (fallopian) tubes, uterus (“womb”), vagina (birth canal), and vulva
Info about the ovaries
Located in pelvic cavity on lateral sides of uterus and connected to body wall by ligaments that are continuous with the peritoneum.
Histology = 4 layers (from superficial to deep):
a) surface (germinal) epithelium - layer of cuboidal epithelial
cells (modified visceral peritoneum LACKING CT)
b) tunica albuginea - dense CT
c) ovarian cortex - contains ovarian follicles and CT
- follicle = layer(s) of cells surrounding each developing
oocyte that supports and protects it through its
development
d) ovarian medulla - contains blood and lymph vessels,
nerves, and CT
Info about the uterine (fallopian) tubes
3 sections:
a) infundibulum
- suspended over each ovary
- opening of uterine tube into peritoneal cavity
- has finger-like projections called fimbriae that cover the
ovary during ovulation. They help capture and move the
oocyte into the uterine tube.
b) ampulla = middle
- site where fertilization usually occurs
c) isthmus = connects to uterus
Histology:
a) mucosa = simple columnar epithelium
i. ciliated cells (for mvmt.) - help move
oocyte/zygote/morula along the tube
ii. non-ciliated secretory cells w/ microvilli - secretes fluid
that provides nutrients to oocyte/cell mass
b) muscularis externa = smooth muscle - contraction helps
move oocyte/cell mass along the tube
c) serosa = visceral peritoneum
Info about the uterus (“womb”)
Hollow, muscular organ located superior to bladder. 3 parts:
a) fundus = superior to isthmus of uterine tubes
b) body = main portion; space w/in = uterine cavity; site where most embryo implantation and growth occur
c) cervix (neck) = inferior, narrow passageway that opens into vagina
Histology = 3 layers:
a) endo(inside)metrium = mucous membrane composed of a simple columnar epithelium that lines the inner surface of the uterus and a specialized lamina propria
i. functional layer (stratum functionalis)
- superficial layer
- dvlp.s at puberty and is shed monthly (menstruation)
along w/ the simple columnar epithelium
- contains endometrial glands (epithelial tissue) that
secrete a nutritive fluid for the embryo prior to
formation of the umbilical cord
ii. basal layer (stratum basalis)
- permanent layer attached to myometrium
- undergoes mitosis to replace the stratum functionalis
and the simple columnar epithelium
b) myometrium (muscularis externa) = smooth muscle
c) perimetrium (serosa) = outer layer, visceral peritoneum
Info about the vagina (birth canal)
Connects uterus to external genitalia. Female organ of copulation. Histology:
a) mucosa = thick stratified squamous epithelium; has rugae
b) muscularis externa = smooth muscle
c) adventitia = fibroelastic CT
Info about the vuvla
Reproductive structures that lie external to the vagina.
a) mons pubis
- adipose tissue that overlies and cushions pubic
symphysis
b) labia majora/minora
- labia major = 2 large skin folds that surround the labia
minora
- the labia minora are small inner folds of skin that
surround the vestibule
c) vestibule, containing:
i. vaginal opening
ii. external urethral orifice - anterior to vaginal opening in
anatomical position
d) greater vestibular glands
- secrete mucus to lubricate the vestibule
e) clitoris
- mainly internal, w/ small external portion at anterior
junction of labia minor
- contains erectile tissue
- derived form the same embryonic tissue as the penis
What is oogenesis?
= Gamete production (w/in ovarian follicles)
*See pg. 6 for flow chart
- 1 primary oocyte forms 1 ovum and 2 or 3 polar bodies
- polar bodies are discarded nuclear material
- oogonia: diploid stem cells that multiply by mitosis during fetal development
- differentiate into primary oocytes
- primary oocytes (2n): about 1 million in ovaries at birth
- enter meiosis I before birth, but arrested in prophase I
- at puberty, less than half of oocytes remain
- secondary oocyte (n):
- begins meiosis II and arrests in metaphase II
- this is ovulated (usually 1/month)
- about 500 ovulated from puberty to menopause
What are the 3 stages of ovarian follicles and follicular development?
Late embryonic and fetal period (before birth), childhood - ovary is mostly inactive, and puberty
Info about stage 1: late embryonic and fetal period (before birth)
- germ cells migrate to the developing gonads where they differentiate into oogonia
- oogonia begin to proliferate (growing in #) in the embryonic period until several million are formed, at which point proliferation ends
- oogonia begin to differentiate into primary oocytes during the early fetal period - meiosis I begins, but stops in prophase I (meiotic arrest continues until puberty)
- primordial follicle forms - primary oocytes become surrounded by single layer of flat pre=granulosa (follicular) cells
- most primordial follicles w/ primary oocytes begin to degenerate over time, such that there are fewer at birth
Info about stage 2: childhood - ovary is mostly inactive
- some of the primordial follicles develop into primary follicles: the single layer of flat pre-granulosa cells becomes cuboidal - now called granulosa cells
- however, in the absence of reproductive hormones, primordial and primary follicles also continue to degenerate such that less than half a million primary oocytes are left at puberty
Info about stage 3: puberty
- ovarian cycles and reproductive hormone secretion beings
- each month, primary follicles continue to form and reproductive hormones selectively stimulate some of these follicles to continue their development in the ovarian cortex. They pass through one or more of the following stages (a-e)
Stage 3: puberty - substage a
Secondary follicle
- during the transition from primary to secondary follicle, hormone secreting theca cells form from surrounding CT cells
- granulosa cells proliferate (become stratified) and start to secrete fluid and estrogen
- fluid-filled spaces btw. granulosa cells start to develop as fluid accumulates
Stage 3: puberty - substage b
Vesicular (antral) follicle
- the fluid-filled spaces unite into a single large antrum
- granulosa cells that still surround oocyte = corona radiata
- usually, only one dominant vesicular follicle will continue development from this point per ovarian cycle
Stage 3: puberty - substage c
Preovulatory (graafian) follicle - mature vesicular follicle
- the follicle grows significantly in size and protrudes from
the surface of ovary
- rising hormone levels cause:
i. formation of a secondary oocyte - completion of Meiosis
I; enters Meiosis II and arrests (stops) in Metaphase II
ii. ovulation - release of secondary oocyte (surrounded by
corona radiata) from follicle into peritoneal cavity (follicle
remains in ovary)
- if fertilization occurs, the acrosome of a single sperm
will penetrate the corona radiata
Stage 3: puberty - substage d
Corpus luteum
- follicle that remains after ovulation
- produces high levels of hormones that support fetal development
- if there is no pregnancy, it degenerates into the corpus albicans
