module 1 Flashcards
Gametes
Are the mature, specialized sex cells which are capable of fusing with the sex of the opposite sex to form a zygote
Haploid cells:
cell that contain a single set of chromosomes, carries only one member of the sex chromomere pair
Gonads
Are the primary sex organs
what do gonads produce
gametes and sex hormones that regulate the reproductive process
Reproductive Ducts
Designed to transport and/or store the gametes after they have been produced
External Sex Organs
Make possible the delivery of gametes to facilitate their fusion (fertilization)
basic components of the reproductive system
- gametes
- gonads
- reproductive ducts
- external sex organs
gametes, Female
Ova or eggs
gametes, male
Sperm
Reproductive ducts Female
- Fallopian tubes
- vagina
Reproductive ducts males
- Epididymis
- Vas deferens
- Ejaculatory ducts
- Urethra
Gonads females
Ovaries
Gonads Male
Testes
External sex organs female
vulva
External sex organs male
- Penis
- Scrotum
Diploid cells : formation of gametes
Formation of gametes, termed gametogenesis, includes the meiotic division of precursor diploid cells
after gametogenesis,
the result haploid gametes will contain only one sex chromosome
what chromsome do ova carry
x chromosomr
what chromosome do males carry
x or y
At the moment of fertilization
the sex chromosome carried by the sperm ultimately determines the genetic sex of the zygote and directs the path of development for the resulting embryo
Meiotic division:
meiosis is a special type of cell division that reduces the chromosome number by half, creating haploid cells
Embryo:
the developmental stage between the moment of fertilization and until 8 weeks of development
what is the SRY gene
This gene is found on the Y chromosome and is called the SRY gene Sex-determining Region of the Y chromosome
Indifferent gonads
the stage of the undifferentiated mammalian gonads when neither male or female characteristics have been acquired
Male Gonad development:
To be a male, individual must be exposed to a cascade of factors initiated by the SRY gene
what does the SRY gene encode
a protein, activating the gene required for the development of the testes at week 7 of development
what does the SRY suppress
genes that are important for female development
Spermatogonia
the undifferentiated male germ cells from which mature sperm develop
Female Gonad development:
Females don’t have a Y chromosome so they DON’T have a SRY gene
- therefore other gene expressed that lead to development of oogonia and ovaries
what has happened to some males with no working SRY gene
seen to develop female reproductive systems instead of male supporting the role of SRY gene
Intersex disorders:
- Cause physiological variations in sexual characteristics that do not fit the typical definition of either male or female
- Problems with the normal development of reproductive organs and can also involve metabolic abnormalities with wide health implications
examples of intersex disorders
turner syndrome
turner syndrome
- Female is partially or completely missing one of her X chromosomes
- Non-functioning ovaries, heart defects, hormonal imbalances, and impaired skeletal development, among many other health issues due to the loss of important functional gene
Sex-linked disorders
- Caused by genetic abnormalities inherited through sex chromosomes only
- Do not always effect the sexual characteristics of an person
example of a sex-linked disorder
- As males only have a single X chromosome, any mutations carried in the maternal X chromosome will be expressed in an autosomal dominant fashion
- Females have 2 X chromosomes, so are much more resilient to X-linked sex disorders
is there differnece between male and female embryos during first stages of development?
no.
Indifferent stage
the period preceding sexual differentiation, when no differences can be observed between genetic male and female embryos
when does the indifferent stage occurs
week 0-6 of ferilization
Blastocyst Formation:
- The embryo starts as a simple bundle of cells
- After fertilization it will begin to divide and grow so it can start developing more complex structures
what does the growing of blastocyst develop into
tissues, organs, finally organ systems
Early blastocyst:
- an inner and outer layer form
- Trophoblast layer anchors the blastocyst to the uterus
- Inner cell mass can go on to for, the embryo proper
Late blastocyst:
- Outer cells are busy anchoring the embryo to the uterus
- Inner cells go on to form a flattened plate with 2 distinct tissue
Layers epiblast, hypoblast - Only the epiblast will participate in embryo development
what is gastrulation
Landmark stage
- Embryo establishes 3 germ layers that provide the source tissue of all organ systems
what/where is the embryo at the start of gastrulation
week 2 of development the embryo is already securely attached at its permanent location for the rest of pregnancy**
what happens during gastrulation
- The epiblast folds inward forming the primitive streak through process known as invagination
- As they migrate inwards, they differentiate and form the 3 germ layers
what are 3 germ layers
- Ectoderm
- Mesoderm
- Endoderm
Primitive streak
a structure that forms in the early embryo stages, which indicates the start of gastrulation
what happens once the 3 germ layers are formed
each germ layer will give rise to the tissues from which specific structures and organ system will form
Embryonic folding: what does it establish
- bodily axes, dorsoventral and cranial-caudal axes
- future position and location of all organ systems
when does embryonic folding occur
between week 3 and 4 of feralization
Gonadal development:
- Tissues begin to differentiate and grow, embryo will begin the process of sexual differentiation, along with the development of other organs
what are the first component of the reproductive system
gonads
where do gonads begin developing from
mesoderm layer (source of all tissues from the reproductive system)
when does gonadal development occur
Week 4 of development
Tissues ridges
known as genital or gondal ridges
what is the earliest cells associated with emergence of gonads
Primordial germ cells
PGCs:
migrating towards the gonadal ridges around week 4 of development, arriving and invading area around week 6
before arrival of primodial germ cells
the gonadal ridges will form finger-like tissue projections known as primary sex cords
after arrival of PGCs
interact with this tissue and, depending on the genetic sex of the embryo, will go to form the structures of either male gonad (testis) or female gonad (ovaries)
what happens if primordial germ cells don’t arrive at the gonad ridges
no gonads will develop
Male gonadal development:
- The SRY gene found on the Y chromosome prompts the development of the testes
- Primary sex cords develop to form the primitive testes, which begin to produce testosterone, the major androgen in males
- Testosterone will direct the development of the male reproductive ducts
when does male gondal development occur
week 7 and 8
what does Dihydrotestoerone (DHT) do
is synthesized from testosterone will direct the development of external male genitalia
what do testes produce
Testes produce anti-mullerian hormone (AMH)
what happens in the 3rd month 10-13 weeks of male development and the testes
need to migrate outside the body into scrotal sac
testi migration
- ## is vital for the proper function of testes, and is commonly referred to as the descent of the testes
what is testes migration influenced by
Influenced by a combination of growth processes and hormones
descent of the testes: second month
- Is facilitated by the gubernaculum testis (a structure that arises in the course of week 7 development)
- Forms at the caudal end of the gonads and attaches in the region of the scrotal swelling the future scrotum
descent of testes : 3rd month
- Between the 7th and 12th week
- Gubernaculum begins to shorten, puling the testes towards their future location in the labioscrotal swelling, pulling the layers of the abdominal wall with it creating the ingunal canal
These layers will become the layers surrounding the testes
descented of testes: final month of pregnancy
Testes reach the scrotum at roughly the time of birth under the influence of specific hormones
Female Gonad development
Absence of SRY, the primary sex cords degenerate, and cortical sex cords begin to develop as the gonads take the path towards ovarian development
what do the coritcal sex cords for females develop
form the ovarian follicles
○ Site of oocyte production
gubernculum female gonad developement
- causes the ovaries to change their position slightly
- goes on to form the ovarian ligament and further down the round ligament of the uterus that reaches the labia majora through the inguinal canal
Migration anomalies
Can cause pathology of the inguinal canal, such as inguinal hernia or undescended testes
Migration anomalies - Males
- More prone to inguinal hernias than females
- ## Due to the migration process during the descent of the testes
what happens as testicles descend down the inguinal canal
they create a gap in the abdominal muscle after birth- which makes them more likely developing inguinal hernia
Migration anomalies - female
Inguinal canal is much smaller
what is undescended testes called
Cryptorchidism
how/when do undescended testes occur
- when one or both testicles fail to complete their migration toward the scrotum
what can undescended testes lead to
- impaired sperm production as the testis need to be at a slightly lower temperature than body temperature for sperm production to proceed normally
Male and female genital duct development- when does it start
week 4 all embryos develop 2 pairs of ducts which become the origin of the entire genitourianry duct system
what are the 2 ducts both females and males develop in week 4
- wolffian (mesonephric) ducts
- mullerian (pharmacophoric ducts)
where do to common week 4 ducts originate from
common region in the mesodermal layer called the intermediate mesoderm and end at the clocac at the caudal end of the primitive gut
female developing ducts/how- mulleruan ducts
The absence of testosterone causes the mullerian ducts to go on to form the fallopian/uterine tubes, the uterus, and the upper portion of the vagina
male developing duct/how: mullerian ducts
Developing testes produce testoerone and antimullerian hormone- causing the mullerian ducts to regress around week 8 of development
female developing ducts - wolffian duct turn into what?
go on to differentiate and form the epididymis
male developing ducts - wolffian duct turn into what?
go on to differentiate and form the epididymis, vas/ductus deferens, the seminal vesicles, and ejaculatory ducts, a process which is completed by week 12 of development
female when do the wolffian ducts regress
approx. week 10
when does external genitalia development occur
Begins around week 3 no difference can be detected between male and female embryos until around week 9
external genitalia: Undifferentiated: stage end of week 5
cloacal fold form on both sides of the urogenital sinus and are joined by the genital tubercle at the anterior end
external genitalia: Undifferentiated: stage by 7th week
he cloacal folds have differentiated into the urogenital fold and the anal fold
- Genital swellings develop from the lateral part of the genital tubercle
external genitalia: week 10 in male
exposure to dihydrotestosterone (DHT) results in growth of the genital tubercle and an increase in size of the genital swellings
external genitalia: week 10 in female
there is minimal growth of the genital tubercle and genital swellings
newborn: extenral genitalia male
the genital tubercle continues to grow to form a phallus, and the urogential folds fuse to form a scrotum
newborn: extenral genitalia female
the genital tubercle develops into the clitoris, and the urogenital fold do not fuse but give rise to the labia majora and labia minora
Three primary functions: males
- To produce and maintain sperm cells
- to transport and deliver sperm cells into the female reproductive tract
- To produce and secrete sex hormone
male external organs
Penis
Scrotum
Epididymis
Testes
function of penis
Serves as both a reproductive and urinal duct
- Passage of both urine and semen
what are the 3 columns of tissue in males
- corpora cavernose
- Corpus spongiosum
- tunica albuginea
layout of the 3 penis tissue
- 2 corpora cavernose that lie next to each other on the dorsal side
- Corpus spongiosum that lies between the corpora cavernosa on the ventral side
- Surrounding the corpora cavernose is a tough of connective tissue called the tunica albuginea
The glans penis what is functin and how is it formed
- Is the bulbous end of the penis formed by the corpus spongiosum
Supports the foreskin (prepuce) that retract to expose the glands
Penile Fracture
- Can “break”
- Involves a rupture in the tunica albuginea (layer coving the corpora cavernosa)
- Is a medical emergency due to the injury to urethra, nerves, and blood vessel of the penis, requiring surgical intervention
what is the scrotum
Dual chambered suspended sack of skin and smooth muscle that contains the testes
what casues the colour and hair on scrotum
Increased testosterone secretion during puberty causes the darkening of the skin and development of pubic hai
function of scrotum
- the temp of the testes slightly lower than that of the rest of the body
- left testis is usually lower than the right, which may function to avoid compression in the event of impact and to allow more effective cooling
what is the degrees drop it should be for optimal sperm production
2 degrees below body temp
testes function
male gonads
- production of sperm
layers of scrotal sac
- scrotal skin
- dartos fascia and muscle
- external spermatic fascia
- cremaster muscle
- internal spermatic fascia
- tunica vaginalis
- tunica albuginea
Scrotal skin
the external most later
Dartos fascia and muscle
a layer of fascia and smooth muscle that carriers the blood supply to the skin, helping regulate the testes temp
External spermatic fascia:
a thin layer of fascia
Cremaster muscle:
a layer of smooth muscle that carriers blood and nerve supply to the testes, and is responsible for the cremasteric reflex of the scrotum
Internal spermatic fascia:
thin layer of fascia
Tunica albuginea
the final and inner most layer covering the teste
Tunica Vaginalis:
a serous membrane that covers the testis. It is continuous with the surface of testis and the internal surface of the scrotum, creating a pouch or cavity in between
what are under the tunica albuginea of males
seminiferous tubules
what happens in the Seminiferous tubules
site of spermatogenesis
Spermatogenesis
production or development of mature spermatozoa
Cells of the seminiferous tubules
- Spermatogonial stem cells
- Sertoli cells
Spermatogonial stem cells
Become mature sperm
Sertoli cells
Facilitate the process of sperm maturation
what Located between seminiferous tubule
Leydig cells
Leydig cells
Produce and secrete testosterone and other androgens required to sustain spermatogenesis, sexual development, and puberty
types of Seminiferous Tubules
- Convoluted
- Straight
Seminiferous Tubules: Convoluted
Located toward the lateral side
Seminiferous Tubules: Straight
As the tubule comes medially to form ducts allowing sperm to exit the testis
Rete Testis:
► Follow the seminiferous tubules
► Network of tubes where the sperm are mixed and some fluids are reabsorbed
where do Rete Testis: exit
into efferent ducts
Efferent ducts:
► Sperm are further concentrated via reabsorption of fluids
what do the efferent ducts connect with
the initial section of the epididymis
Epididymis:
- Where newly created sperm cells mature
- Single tightly coiled tube
what are the sperm like in the epididymis
Sperm cells are not motile at this point, the peristaltic movement of the epididymis push the sperm forward
where do sperm go after epididymis
Vas Deferens:
Vas Deferens:
► After epididymis sperm moves into the vas deferens
► Transported to the ejaculatory ducts
► Empty into the urethra for expulsion
Vasectomy :
- Deferentectomy
- Method of contraception in which the vas derens are permanently cut
- Modern procedure: injecting an obstructive material into the ducts to block the sperm going out (not cutting required)
Genital (accessory) glands function
- Produce seminal fluid
- They lubricate and clean the urethra
what are the genital accessory glands
Seminal vesicles:
Prostate gland:
Bulbourethral glands:
Seminal vesicles:
- Are sac-like pouches that attach to the vas derends near the base of the bladder
- Produce molecules such as fructose that serve as energy sources for sperm
what makes up 50-70% of mans ejaculation
Seminal fluid
Prostate gland:
- Walnut sized
- Below urinary bladder, infront of rectum
- Contributes additional fluid to the ejaculate that serves as nourishment for sperm and contributes to sperm motility
what is the prostate gland composed of
muscular tissue that ensures seminal fluid is forcefully expelled into the urethra and outwards during ejaculation
Bulbourethral glands
- Are pea-sized structures located on the sides of the urethra just below the prostate gland
- Produce clear, slippery fluid that empties directly into the urethra
- Fluid produced lubricates the urethra and neutralizes acidity associated with residual urine
Functions of the female reproductive system
- Production and transport of female gametes, the oocytes
-The reception and transport of male gametes, the sperm - Maintenance of the developing fetus
Birthing and post-natal nourishment of the baby
The ovaries:
Are the ovum-producing organs (gonads)
Paired ovaries: attached by
fibrous cord called the OVARIAN LIGAMENT
The ovaries: ethered to the body wall by
the suspensory ligament of the ovary and located within the peritoneal cavity
Structure of the ovaries:
- Germinal epithelium
- Tunica albuginea:
- Ovarian cortex
- Ovarian medulla
Germinal epithelium
The outermost layer covering the ovary
Tunica albuginea:
A fibrous layer of connective tissue that protects the inner structures of the ovary
Ovarian cortex
Contains supporting connective tissue and the ovarian follicles, and therefore is the site of oocyte production
Ovarian medulla
Contains the majority of the vascular tissue that supports the ovary
Ovarian follicles and ovulation:
Site of oocyte production
Each follicle contain
single, immature oocyte that periodically and cyclically matures and develops under the influence of sex hormones
Ovarian follicles, Cellular composition
- Changes according to their maturation stage
- Can be determined by their size
- When oocyte maturation is completed, the follicle ruptures and the oocyte is release
When one ovary is absent or dysfunctional,
,the other will continue to release eggs each month
Ovarian hormones:
Estrogen
Progesterone
Estrogen
Responsible for the appearance of secondary sex characteristics in females at puberty and for the maturation and maintenance for the reproductive organs in their mature functional state
Progesterone
Functions with estrogen by promoting menstrual cycle changes in the uterus and by helping sustain pregnancy
The uterus
- Largest and major organ of the female reproductive system
- Is hollow muscular organ about the size of a pear
- Located in the pelvic cavity, between the rectum and the bladder
- Body uterus opens into the vagina via the cervix with the other end, the fundus is connected to the fallopian tubes
Layers of the uterus
Endometrium
Myometrium:
Perimetrium
Endometrium:
innermost layer, site for implantation of the embryo. Responsible for the changes observed during the menstrual cycle
Myometrium
middle layer consisting of smooth muscle. Contains 3 layers going in different directions, which provide support during the distension caused by pregnancy, and faciliate the contraction during birthing
Perimetrium
is the serous outer covering of the uterus
Functions of uterus: During intercourse,
it directs blood flow to the pelvis and to the external genitalia, including ovaries, vagina, labia, clit
Functions of uterus
- Receive a fertilized ovum which passes through the utero-tubal junction form the fallopian tube
Functions of uterus - After implantation
into the endometrium, the embryo derives nourishment from blood vessels
Female genital ducts: the fallopian tubes
- oviducts or uterine tubes, are 2 very fine tubes lined with ciliated epithelia that connect the ovaries to the uterus
Female genital ducts: the fallopian tubes function
Allow passage of the egg from ovary to uterus
Different segments: of the fallopian tubes
Infundibulum:
Ampulla
Isthmus
Infundibulum
associated with fimbriae near the ovary
Ampulla:
the major portion of the lateral tube and where fertilization normally takes place
Isthmus:
the narrower part of the tube that links to the uterus
Epithelium of the fallopian tubes:
Ciliated cells
]Peg cells
Ciliated cells
- Predominate throughout
- Are most numerous in the infundibulum and ampulla
- Estrogen increases the production of cilia on these cells
- Interspersed between these cells are peg cells
Peg cells
- Contain apical granules and produce the tubular fluid
- Fluid contains nutrients for spermatozoa, oocytes, zygotes
- Secretions also promote maturation of the sperm by removing glycoproteins and other molecules from the plasma membrane of the sperm
Female genital ducts: the Vagina
- Is a fibromuscular tubular tract that leads from the opening of the vulva to the cervix, the opening of the uterus
the Vagina 2 primary functions
- Sexual intercourse
- Childbirth
Vagina during arousal
produces secretion to facilitate the entrance of the penis
A series of ridges produced by the folding of the wall of the outer third of the vagina is called the
vaginal rugae
Transverse epithelial ridges provide the vagina
increased surface area for extension and stretching
external organs: the vulva
Mons pubis:
Labia
Urinary orifice:
Clitoris:
Vaginal orifice:
Mons pubis
pubic region directly in front of the pubic bone
Labia:
majora and minora are the folds of skin tissue that cover and protect the more delicate structures of the clit, urinary orifice, and vaginal orifice
Urinary orifice
vulva also contains the opening of the female urethra, and thus serves the vital function of passing urine. Is the external opening of the urethra
Clitoris
small projection of highly innervated, erectile tissue, structurally homologous to the penis, except it plays no role in urination
Vaginal orifice:
is the external opening to the vagina, which functions as receptacle for the penis during intercourse
Bartholin’s:
- Are a pair of secretory glands located to the left and right of the vaginal opening
- Secrete mucus to lubricate the vagina and are homologous to bulbourethral glands in males
Skenes glands:
- pair of secretory glands which open to the left and right side of the urethral orifice during
- During sexual arousal, they secrete fluid, although it is unclear how much they contribute to lubrication and whether they have additional functions
Mammary glands
- In females that produces milk to feed young offspring
- Are located within the female breast
- 15 to 20 irregularly shaped lobes, each which includes alveolar glands, and lactiferous duct that leads to the nipple and opens to the outside
lobes are separated by?
dense CT that support the glands and attach them to the tissues on the underlying pectoral muscles
Lactiferous duct:
- Development occurs in females in
response to circulating hormones - Development begins during the pre- and postnatal stages, and resumes in puberty
- Estrogen promotes branching differentiation, which is inhibited by testosterone in males
