Reproductive System Flashcards
What is the urogenital ridge?
Region of intermediate mesoderm giving rise to the embryonic kidney and the gonad.
Where do the primordium germ cells originate?
Yolk sac.
What genes are expressed by the Y chromosome?
SRY genes.
What structural features of the gonad develop with an XY genotype?
Medullary cords develop but no cortical cords.
Thick tunica albuginea (outer capsule).
What structural features of the gonad develop with an XX genotype?
Medullary cords degenerate and cortical cords develop.
No outer capsule as the oocytes must be able to ovulate through the gonadal wall.
What is the urogenital sinus?
Region of the hindgut created by the urorectal septum that is continuous with the umbilicus.
What is the adult remnant of the urachus?
Median umbilical ligament.
Outline the process of the development of the internal male reproductive tract:
Mesonephric ducts sprout ureteric buds at the urogenital sinus and make independent openings.
Mesonephric ducts are maintained by dihydrotestosterone.
Paramesonephric ducts degenerate in males under the influence of Mullerian Inhibiting Substance (MIS).
Outline the process of the development of the internal female reproductive tract:
Mesonephric ducts regress due to lack of androgens.
Mullerian/paramesonephric ducts continue to develop and fuse to form the uterus, cervix and fornices.
The urogenital sinus expands and elongates to form the vagina.
What features of the external genitalia are found during the indifferent stage?
Genital tubercle
Genital folds
Genital swellings
How does the external genitalia of the male develop?
The genital tubercle elongates and the folds fuse to form the spongy urethra under the influence of androgens.
How does the external genitalia of the female develop?
There is no fusion of the genital folds and the urethra opens into the vestibule; the genital tubercle becomes the clitoris.
What is the processus vaginalis?
An invagination of the peritoneum that creates a path for the descent of both testis through the inguinal canal.
What is the gubernaculum?
Fibrous cord connecting the ovary to the labioscrotal folds via the uterus and the testis to scrotum.
How is genetic variation produced?
Crossing over
Random segregation
Independent assortment
What forms the blood-testis barrier?
Tight junctions between Sertoli cells within the seminiferous tubules separating the basal and adluminal compartments.
Outline the basic process of spermatogenesis:
Spermatogonia divide by mitosis to form the ad and ap spermatogonia.
Ap spermatogonia become primary spermatocytes.
Primary spermatocytes divide by meiosis to produce secondary spermatocytes and spermatids.
Haploid spermatids differentiate into spermatozoa by spermiogenesis.
What is the spermatogenic cycle?
Not all stages of spermatogenesis are visible in cross-section at once; the spermatogenic cycle is the time taken for the reappearance of the same stage of spermatogenesis within a given segment.
What is the spermatogenic wave?
The distance between the same stages of the cycle.
What is spermiation?
The release of sperm into the seminiferous tubules where they remodel to form spermatozoa.
What is the composition of semen?
Vas deferens (5%)- sperm Seminal vesicles (70%)- amino acids, citrate, fructose and prostaglandins Prostate (25%)- proteolytic enzymes and zinc
What is the purpose of Cowper’s glands?
Produce mucoproteins that help to lubricate the urethra and neuralise acidic urine in the distal urethra.
What is sperm capacitation?
The final maturation step that occurs in the female gential tract that includes removal of glycoproteins and cholesterol from the sperm cell membrane and activation of sperm signalling pathways.
Outline the basic process of oogenesis:
Germ cells differentiate into oogonia.
Oogonia proliferate by mitosis.
Primary oocytes enter meiosis and arrest in prophase.
Many oocytes/oogonia undergo atresia and the surviving primary oocytes form primordial follicles.
Cells remain arrested meiosis I until puberty.
What are the features of pre-antral follicle?
Production of stratified cuboidal epithelium of granulosa cells that secrete glycoproteins to form the zona pellucida.
What are the features of the antral follicle?
Theca externa and interna develop.
Granulosa cells surrounding the oocyte are known as the cumulus oophorus.
Antrum is formed by the coalescence of fluid filled spaces between granulosa cells.
What are the features of the pre-ovulatory follicle?
Meiosis I completes producing the oocyte and first polar body.
Cell enters meiosis II and arrests in metaphase.
How is the oocyte released from the ovary (ovulation)?
LH surge stimulates collagenase activity.
Prostaglandins respond to raised LH and cause local muscular contractions of the ovarian wall allowing the oocyte to be extruded.
What is the corpus luteum?
The remaining follicle after extrusion of the oocyte that secretes oestrogens and progesterone for 14 days after ovulation (unless fertilisation occurs).
What is the corpus albicans?
Fibrotic mass of scar tissue formed from the degeneration of the corpus luteum.
Outline the basis of the hypothalamic-pituitary-gonadal (HPG) axis for both males and females:
Hypothalamus produces GnRH that acts on the pituitary gland to release LH and FSH.
LH and FSH act on the reproductive system and exert negative feedback onto the hypothalamus.
Specifically where to LH and FSH act in the male and what effects do they produce?
LH acts on Leydig cells to produce Testosterone.
FSH acts on Sertoli cells to produce Inhibin and ABG (binds testosterone to keep it in the seminiferous tubules)
What is the action of inhibin?
Specifically inhibits the release of FSH by feeding back negatively on the pituitary gland.
What are the products of ovarian stimulation by LH and FSH in females and where are they produced?
Oestrogen from granulosa cells (LH)
Progesterone from the corpus luteum
Inhibin from granulosa cells (FSH)
Explain the differences in oestrogen feedback over the course of the menstrual cycle:
Initially oestrogen feeds back negatively on the hypothalamus and pituitary.
Once oestrogen levels are high this changes to positive feedback resulting in the LH surge.
After ovulation progesterone production by the corpus luteum in combination with the high oestrogen levels results in negative feedback again to reset the axis.
What is meant by the waiting phase of the menstrual cycle?
Maintenance of the endometrium until a signal is recieved to indicate that fertilisation has/has not occurred.
If fertilisation occurs what signals alert the female reproductive tract?
The syncytiotrophoblast produces hCG which exerts a luteinising effect to maintain the corpus luteum.
What actions does oestrogen produce in the female reproductive tract?
Contributes to Fallopian tube function
Produces thickening of the endometrium
Contributes to growth and motility of the myometrium
Thin, alkaline cervical mucus
What actions does progesterone produce in the female reproductive tract?
Thickening of the endometrium and myometrium
Thick, acidic cervical mucus
Increased body temperature
How is variation in the length of menstrual cycles produced?
Variation in the follicular phase as the luteal phase is strictly controlled.
What is thelarche?
Development of breasts
What is puberache?
Development of axillary and pubic hair
What is meant by puberty?
The completion of sexual maturation and growth in humans, onset typically between the ages of 8-13 years.
What factors contribute to the onset of menarche?
First menstrual period usually occurs between 8-13 years and there is a critical weight of 47kg.
What are the first phenotypic changes observed that mark the beginning of puberty?
Breast development in girls
Testicular enlargement in boys
What effects do androgens have in both boys and girls?
Mineral retention to support bone and muscle growth
Growth of pubic hair
Sebaceous gland secretion
How do we measure what stage of puberty a child is at?
Tanner Standard staging
How do we define precocious puberty?
Onset occurring younger than 2 standard deviations before the average age i.e.
How do we define delayed puberty?
Initial physical changes not present before age 13 in girls or by age 14 in boys.
Alternatively this can also be considered with primary amenorrhoea at 16 years or if the interval between first signs and completion of genital growth in boys/menarche in girls is greater than 5 years.
What physiological features occur in pre-menopausal women?
The follicular phase shortens
Ovulation becomes earlier/absent due to decreased oestrogen production (and resulting increased LH and FSH)
Reduced feedback and reduced fertility
How do we define menopause?
12 clear months with no menstrual period.
What are some of the symptoms of the menopause?
Vascular changes causing ‘hot flushes’
Regression of the endometrium and shrinkage of the myometrium
Thinning of the cervix and decreased vaginal tone
Changes in skin
Involution of breast tissue
Decreased bladder and pelvic tone
What is dysfunctional uterine bleeding?
Uterine bleeding with no recognisable pelvic pathology, pregnancy or bleeding disorders.
What are fibroids?
Leiomyomas- benign tumours of the myometrium that may be subserous, intramural or submucous.
What is meant by menorrhagia?
Heavy vaginal/menstrual bleeding that may be described as “flooding”/passing clots etc.
What is the difference between primary and secondary amenorrhoea?
Primary amenorrhoea means that the woman has never had a menstrual period.
Secondary amenorrhoea indicates that the woman has previously had a menstrual period but has not had one for more than three cycles.
What are some of the advantages of HRT?
Relieves symptoms of menopause
Improves wellbeing
Limits osteoporosis
What are some disadvantages of HRT?
Increased risk of breast/ovarian/uterine cancer
Increased risk of stroke
What is the tunica vasculosa?
Vascular layer below the outer tunica albuginea and the seminiferous tubules.
What is the structural arrangement of the seminiferous tubules?
Each lobule of seminiferous tubules is surrounded by perilobular connective tissue.
What epithelium is found in the efferent ductules and how does this relate to its function?
Ciliated simple columnar/cuboidal cells that act to absorb excess fluid from the seminiferous tubules.
What epithelium is found in the epidydimis?
Pseudostratified columnar epithelium with stereocilia
Where is testosterone produced?
Islands of specialised Leydig cells found between the seminiferous tubules.
What is the role of the cytoplasmic bridges observed between developing gametes?
Ensures that the gametes mature simultaneously.
What are the seminal vesicles?
Outgrowths of the ductus deferens forming coiled tubulosaccular glands with pseudostratified columnar epithelium.
What does the prostate gland consist of?
Tubuloalveolar glands arranged in groups of three around the urethra.
How is the structure of the prostate gland organised?
The fibromuscular capsule has septae that divide the gland into lobules.
What are corpura amylacea?
Lamellated bodies found in older men that contain proteins, amino acids, cholesterol and calcium phosphate.
What is the scrotum?
A cutaneous sac developed from the labioscrotal folds under the influence of DHT.
How can you differentiate between a hydrocoele and haematocoele?
Transillumination (haematocoele produces red/pink light)
What is the arterial supply to the testis?
Direct testicular branches of the abdominal aorta.
What is the venous drainage of the testis?
Right testicular vein to the IVC
Left testicular vein to the left renal vein
What is the course of the spermatic cord?
From the deep inguinal ring to the posterior border of the testis via the inguinal canal and superficial inguinal ring.
What are the layers of skin/fascia surrounding the testis and from where do each of them originate?
Internal spermatic fascia (transversalis fascia) Cremasteric muscle (Internal oblique) External spermatic fascia (aponeurosis of external oblique)
What is the difference between indirect and direct hernias?
Indirect hernias pass through the deep inguinal ring and then along the inguinal canal and can pass down into the scrotum to affect the testis.
Direct hernias protrude directly through the posterior wall of the inguinal canal, medially to the epigastric vessels.
What is the function of the pampiniform plexus?
Acts as a heat exchanger to reduce the temperature of the scrotum and testis in order to find the optimum temperature for spermatogenesis.
What structures are found in the spermatic cord?
Vas deferens
Testicular artery
Genitofemoral nerve
Pampiniform plexus
What is the innervation to the scrotum?
Lumbar and sacral plexuses
Where is the lymphatic drainage of the testis to?
Para-aortic nodes
Where is the lymphatic drainage of the scrotum to?
Superficial inguinal nodes
Which arteries supply the penis?
Internal pudendal arteries
What is the role of the superficial perineal muscles in maintenance of erections?
Bulbospongiosus- helps expel last drops of urine and maintain erections
Ischiocavernosus- compresses veins to help maintain erections
What makes up the linea terminalis?
Arcuate line, pectineal line and pubic crest
What is the sacral promontory?
Prominence where the sacrum projects into the pelvic cavity
What are the features of the ideal gynaecoid pelvis?
Well curved sacrum Well rounded greater sciatic noth Straight side walls Small ischial spines Sub-pubic arch >90 degrees
What is the obstetric conjugate?
Measured from sacral promontory to the midpoint of the pubic symphysis
What is the diagonal conjugate?
Measured from the sacral promontory to the inferior border of the pubic symphysis
What makes up the pelvic outlet?
Infrapubic angle and the distance between ischial tuberosities
What ligaments support the pelvis?
Sacrospinous ligament
Sacrotuberous ligament
What is the anatomical structure of the ovary?
Outer cortex of germ cells with an inner medulla of nerves, blood vessels, stroma and connective tissue with a hilum found at one pole.
What are the features of the Graafian follicle?
Cumulus oophorus breacks down and the oocyte and corona radiata (layer of granulosa cells) float free in the follicular fluid
What type of epithelium is found in the Fallopian tubes?
Inner mucosa with columnar ciliated epithleium and peg cells (secretory cells that produce a nutrient-rich fluid for the gametes and that promotes capacitation)
What is the histological structure of the endometrium?
Columnar epithelium and lamina propria with glands and stroma
How many layers of smooth muscle make up the myometrium?
4
What is the blood supply to the uterus?
Paired uterine arteries that branch into the arcuate arteries of the myometrium
Straight arteries ramify the stratum basalis
Coiled arteries supply the stratum functionalis
What is shed during menses?
The functional layer of the endometrium (stratum functionalis)
What effects does progesterone have on the endometrium?
Growth and coiling of endometrial glands
Stromal oedema and production of decidual cells
What is the epithelium of the cervix?
Simple columnar epithelium transitions to non-keratinized stratified squamous epithelium
What epithelium is found in the sinuses of the breast?
Cuboidal to columnar epithelium in the ducts that changes to stratified squamous epithelium at the level of the lactiferous sinuses.
What is the course of the round ligament?
The ovarian ligament reflects off of the fundus of the uterus to become the round ligament of the uterus that travels through the inguinal canal to the labia majora.
What is found within the suspensory ligament of the ovary?
Contains an arterial supply, venous and lymphatic drainage of the ovary.
What are the three components of the broad ligament?
Mesovarium
Mesosalpinx
Mesometrium
How is the broad ligament formed?
It is a peritoneal reflection/mesentery.
What is the clinical significance of the posterior fornix of the cervix?
Provides access to the Pouch of Douglas for culdocentesis.
What is the arterial supply to the ovary?
Direct branches of the abdominal aorta
What is the venous supply to the ovary?
IVC on the right and the left renal vein
How would you describe the orientation of the uterus within the pelvic cavity?
Anteverted with respect to the vagina
Anteflexed with respect to the cervix
How is the pelvic viscera supported?
Transverse cervical ligament
Uterosacral ligament
Round ligament
What is meant by redundancy of supply?
There are numerous anastomoses of the arterial supply to the female reproductive tract so the loss of one artery will not result in ischaemia of any one part of the tract.
Where is the lymphatic drainage of the fundus to?
Para-aortic and inguinal nodes
Where is the lymphatic drainage of the body of the uterus to?
External iliac nodes
Where is the lymphatic drainage of the cervix to?
Iliac and sacral nodes