Repro Flashcards
How is the development of secondary sex characteristics controlled?
Hormones: gonadotrophins + testosterone/oestrogen and progesterone
Describe the migration of germ cells that occurs embryologically.
The germ cells arise in the yolk sac then migrate along the dorsal mesentery to the urogenital ridge to reside within the primordial gonad.
How does development of the primordial gonad into the adult gonads differ according to genetic sex?
In males, germ cells colonise the medullary region and the cortex region atrophies. The germ cells allow rapid growth of the definitive sex cords which they subsequently invade. In the adult these give rise to the seminiferous tubules. The orignial mesodermal somatic cells form Sertoli cels, Leydig cells develop between the sex cords.
In females, germ cells colonise the cortex and so the medullary cords do not develop. The germ cells become surrounded by somatic mesenchymal cells which will eventually form primordial follicles.
Why can female genitalia be considered the “default”?
The cortex of the primordial gonad will develop even if no germ cells arrive.
How are the female internal genitalia formed?
The Mullerian / Paramesonephric ducts grow medially towards each other formining the uterus and its tubes, cervix, fornices and upper 2/3 of the vagina. The rest of the vagina is formed from the sinovaginal bulbs from the vaginal plate which grows from the urogenital sinus.
What is the function of Mullerian Inhibitory Hormone (MIH) and what is it secreted by?
MIH suppresses the growth of the Mullerian / Paramesonephric ducts in the male. It is secreted by Sertoli cells.
What is the genotype of an individual with true hermaphroditism?
Mosaicism of XY and XX or XO
Describe the important features of pseudo-hermaphroditism.
Occurs in individuals with XY genotypes but where foetal genitalia are insensitive to testosterone. The testis are undescended in the lumbosacral region, no internal genitalia will be produced and the external genitalia will be female. Undescended testes have an increased risk of developing germ cell tumours.
What genitalia (internal and external) will develop in an XX individual with congenital adrenal hyperplasia?
Female gonads but both male and female internal genitalia will develop. External genitalia will be male.
Describe the descent of the testes.
Testes start in the lumbosacral region, they then move caudally, crossing the inguinal canal obliquely and an invagination into the scrotum develops to form the processus vaginalis. Around 9 months gestation the testes migrate over the pubic bone to enter the scrotum.
What is the fate of the gubernaculum?
In females the guberaculum becomes the ovarian ligaments that join each ovary to the uterus.
In males the guberaculum becomes the scrotal ligament.
What is hypospadia and how does it develop? What is it associated with?
Hypospadias are where the urethral opening is on the ventral surface of the penis, they form due to incomplete fusion of the urethral folds. They are always associated with descended testes and sometimes with micropenis.
What is uterus bicornis? How does it develop? What are the consequences of it?
Uterus bicornis is where the uterus is “heart shaped” due to incomplete fusion of the paramesonephric ducts. It may cause menorrhagia but fertility is usually unaffected.
Describe the 4 main steps required for gametogenesis.
Colonisation of the gonad
Proliferation by mitosis
Introduction of genetic variation by meiosis
Cytodifferentiation
How does meiosis introduce genetic variation? MGD
Crossing over when pairs of chromosomes become bivalent
Random assortment as chromosomes line up at metaphase
Where does spermatogenesis occur?
In the seminiferous tubules
What is spermiogenesis?
Spermiogeneisis is the cytodifferentiation of spermatids into spermatozoa (mature sperm cells)
When do males start producing sperm?
At puberty
What is the spermatogenic cycle?
The spermatogenic cycle is the time taken for the reappearance of the same stage of spermatogenesis within a given segment of a seminiferous tubule.
What is the spermatogenic wave?
The spermatogenic wave is the distance along the seminiferous tubule between cells undergoing the same stage of spermatogenesis.
Where is the majority (by volume) of semen produced?
The seminal vesicle
What is the function of secretions from the bulbourethral (Cowper’s) glands?
To help lubricate the distal urethra and neutralise any acidic urine present
What is the source of the energy needed by sperm?
Fructose within semen is used to form ATP
What do the prostaglandins in semen do?
To increase sperm motility and to cause smooth muscle contraction within the female genital tract
What processes are involved in sperm capacitation?
Removal of glycoproteins and cholesterol from the cell membrane and the activation of sperm signalling pathways (atypical soluble adenylyl cylase and PKA involved)
What is the acrosome reaction?
The acrosome reaction is the process by which polyspermy is prevented at fertilisation. It is triggered by the binding of proteins on the head if the sperm to ZP3 proteins of the zona pellucida and involves at Ca2+ wave.
What are oogonia?
Diploid immature female reproductive cells produced by differentiation of the primordial germ cells which later form oocytes
When do oocytes complete meiosis I?
In utero - between 3 and 7 months gestation
What cells surround the oocyte once it has become part of a primordial follicle?
Flat epithelial cells of gonadal origin
What happens during the pre-antral stage of the maturation of the ovaries?
Follicular cells become cuboidal and proliferate to form a stratified epithelium of granulosa cells
What happens during the antral stage of maturation of the ovaries?
Fluid filled spaces appear between the granulosa cells and coalesce to form the antrum. The granulosa cells left surrounding the oocyte are then called the cumulus oophorus. The stromal cells form the theca folliculi: the theca externa (outer fibrous layer) and theca interna (inner secretory layer).
When do oocytes complete meiosis II?
At fertilisation
What is the polar body?
Either of two small cells produced during the first and second meiotic divisions in the development of an oocyte, containing little cytoplasm and eventually degenerating.
What stimulates the formation of the Graafian follicle?
The rise in FSH and LH before ovulation
How is the oocyte extruded from the ovary during ovulation?
LH surge increases collagenase activity
Prostaglandins increase the response to LH and cause local muscular contractions of the ovarian wall
What is the name of the cells which develop from the ovarian follicle and produce oestrogen and progesterone?
Lutein cells
What happens to the ovarian follicle if fertilisation does not occur after ovulation?
It degenerates and forms a mass of fibrotic scar tissue known as the corpus albicans
What is the function of human chorionic gonadotropin?
To prevent degeneration of the corpus luteum so that progesterone continues to be secreted to support the pregnancy until placental secretion becomes adequate
After ovulation, how is the oocyte transported to the uterus?
Fimbrae sweep over the surface of the ovary as the Fallopian tube begins to contract rhythmically. The oocyte is carried into the tube by these sweeping movements and the motion of cilia on the epithelial lining. It is then propelled along the tube by peristalsis and the mucosal cilia
How does the hypothalamus communicate with the posterior pituitary gland?
Via impulses that travel through the hypothalmic neurons in the neural stalk
How does the hypothalamus control the anterior pituitary gland?
Via the release of hypothalmic hypophysiotrophic releasing hormones (eg GnRH) which reach the ant pituitary via the hypophyseal portal system
What does the posterior pituitary gland produce?
ADH and oxytocin
What does the anterior pituitary gland produce?
Prolactin, Growth hormone, Thyroid stimulating hormone, Adrenocorticotrophic hormone, Follicle stimulating hormone and Luteinising hormone
How do gonadal cells detect FSH and LH?
Via Gs Protein Coupled Receptors
What is the effect of moderate oestrogen and progesterone on the Hypothalmic-Pituitary-Gonadal axis?
Oestrogen decreases amount of GnRH released per pulse released by the hypothalamus
while Progesterone decreases the frequency of GnRH pulses released by the hypothalamus
Under stimulation from FSH what do Sertoli cells produce, and what is the function of these products?
Androgen binding globulin - binds to testosterone and keeps it within the seminiferous tubules
Inhibin - helps support spermatogenesis and important inhibitory effects
Why is control of reproduction in females so much more complicated than in males?
Female reproductive tract needs to prepare for implantation of conceptus if fertilisation is achieved and also wait for a signal to develop from any conceptus formed, thus two phases (ie the follicular and luteal) are required.
Under stimulation from FSH what do the ovaries produce?
Inhibin
What is the effect of high [oestrogen] in the absence of progesterone?
Gives positive feedback to HPG axis leading to “LH surge”
Why does FSH rise at the beginning of the menstrual cycle?
Little inhibition to FSH secretion (as inhibin levels are low)
After ovulation, what part of the corpus luteum produces oestrogen? And which part produces progesterone?
Oestrogen secreted by theca lutein cells
Progesterone secreted by granulosa lutein cells
How is menstruation initiated?
In absence of further stimulation from LH, the corpus luteum regresses, causing a rapid fall in oestrogen and progesterone. This, in turn, causes the spiral arteries of the endometrium to spasm leading to ischeamic sloughing and thus loss of endometrial tissue
In early pregnancy, what part of the conceptus produces hCG?
The placenta
Describe the cervical mucus produced after menstruation but before ovulation
Thin, watery and alkaline
Describe the cervical mucus produced after ovulation
Thick, sticky and acidic
Describe the main effects of oestrogen on the female genital tract during the follicular phase
Increases motility of Fallopian tubes
Thickening of endometrium and growth and increased motility of myometrium
Cervical mucus is thin and alkaline
Besides the effects on the genital tract, what effects does progesterone have on the female body during the luteal phase of the menstrual cycle?
Changes in mammary tissue (hypertrophy of ducts)
Increased body temperature
Metabolic changes
Electrolyte changes
What is the thelarche?
The beginning of breast development (first stage of female puberty)
How is the pubertal growth spurt controlled?
By the Hypothalmic-Pituitary-Gonadal axis
How are the hormonal changes of puberty initiated?
Increased Gonadotrophin Releasing Hormone secretion from the hypothalamus causing increased stimulation of HPG axis
How does the initiation of androgen secretion support the pubertal growth spurt (in males)?
Stimulates retention of minerals to support bone and muscle growth
What scale is used to assess pubertal development?
Tanner standard (also monitoring of growth spurt)
Below what age would starting puberty be considered precocious?
8 years old in girls and 9 years old in boys
onset occurring at least 2 standard deviations younger than average age
Why is precocious puberty with a gonadotropin independent cause considered pseudo puberty?
It occurs independently of the HPG axis
List some gonadotropin dependant causes of precious puberty
Tumours such as gliomas and pineal tumours
CNS trauma or injury
Hamartomas of hypothalamus
Congenital eg hydrocephalus and arachnoid cysts
(very rarely gonadotropin secreting tumours)
How does Turner’s syndrome cause delayed puberty?
An absent (or structurally abnormal) X chromosome -> gonadal dysgenesis -> hypergonadotropic hypogonadism
How is the menopause diagnosed?
Retrospectively - when cessation of menstrual cycles has been experienced for 12 months
What are “hot flushes” and why do they occur?
Transient increases in skin temperature associated with flushing, they occur due to vascular dilation brought on by the hormonal changes of menopause
Why can the menopause cause urinary incontinence?
Causes changes in pelvic and bladder tone
How can the menopause lead to osteoporosis?
Reduced circulating levels of oestrogens enhances osteoclast ability to reabsorb bone and thus bone mass reduces by 2.5% for several years
What are the risks of HRT?
Increased risk of breast cancer
Increased risk of DVT and VTE can cause strokes and BP effects
Small increased risk of ovarian cancer
Side effects including headaches, bloating, nausea and indigestion
Describe and explain the hormonal changes of menopause
Cessation of development of ovarian follicles causes a dramatic decrease in oestrogen levels which initially causes dramatic increased FSH and increased LH
What, besides problems in the outflow tract, can cause primary amenorrhea?
Gonadal dysgenesis including Turners syndrome
Andogen insensitivity syndrome
Receptor abnormalities for FSH or LH
Congenital adrenal hyperplasia
Or Kallman’s syndrome - problems in hypothalmic devlopment due to a chromosomal defect
What are the most common causes of secondary amenorrhea?
Pregnancy (most common cause), Menopause and Polycystic Ovarian syndrome
How may hypo- or hyperthyroidism affect menstruation?
They can affect the HPG axis and cause amenorrhea (and other menstrual disturbances such as oligomenorrhea or, in hypothyroidism, polymenorrhagia)
How is prolactin secretion regulated?
By Dopamine, Thryotropin releasing hormone (and some other mechanisms)
How can hyperprolactinaemia cause amenorrhea?
Inhibition of oestrogen production due to increased prolactin
What drugs can cause hyperprolactinaemia?
Any that inhibit dopamine: includes anaethesia, opiates and H2antagonists
What are the main hormonal changes in polycystic ovary syndrome (PCOS)?
Increased frequency of GnRH pulse causing an increase in LH pulses and thus increased androgen secretion
What is the linea terminalis?
The line around the pelvis made of the pubic crest, the pectineal line and the arcuate line
What is the “true pelvis”?
The part of the pelvis between the pelvic inlet and the pelvic outlet
How is the size of the pelvic girdle assessed clinically?
By assessing:
Anteroposterior diameter (pelvic inlet)
Bi-spinous diameter (mid-pelvis)
Infra-pubic angle & distance between ischial tuberosities (pelvic outlet)
Distance from the sacral prominence to the the inferior border of the pubic symphysis (diagonal conjugate), allowing an estimate of the true / obstetrical conjugate (the distance between the sacral prominence and the pubic symphysis)
What 2 ligaments are important which regards to the pelvic girdle?
Sacrotuberous ligament - between ischial tuberosity and posterioir ileum, lateral sacrum and coccyx
Sacrospinous ligament - divides sciatic foramen
Approximately what angle of supra-pubic arch provides a ‘good’ pelvis for childbirth?
> 90’
What symptoms can BPH (benign prostatic hyperplasia) cause and why?
Dysuria, Nocturia and Urgency
Due to compresssion of prostatic urethra by enlargement of the middle zone of the prostate
Where are the seminal vesicles located?
Lie above prostate between bladder and the rectum
Describe the course of the vas deferens
Ascends in spermatic cord, passes through inguinal canal, traverses around bladder, and passes on medial side of ureter to form a dilated ampulla
Describe the internal composition of the penis
A pair of corpus cavernosa dorsally
Corpus spongiosum ventrally
All surrounded by tunica albuginea
What is the arterial supply to the penis?
Branches of Internal Puodenal arteries which are themselves branches of anterior division of Internal Iliac artery
What is the function of the bulbous spongiosus muscle?
Helps expel urine or semen and also helps maintain erections
What is the function of the ischiocaverosus muscle?
Compresses veins to help maintain erections
Describe the innervation of the scrotal area
Anterior surface - lumbar plexus
Posterioir and inferioir surfaces - sacral plexus
What is the lymphatic drainage of the scrotum?
To the superficial inguinal nodes
What is the lymphatic drainage of the testes?
To the para-aortic nodes
What is the arterial blood supply to the testes?
Direct branches of the abdominal aorta
What is the venous drainage of the testes?
Left - L renal vein
Right - IVC
What is the function of the dartos muscle?
To wrinkle the scrotal skin to prevent heat loss in cold conditions
Where are the bulbourethral glands located?
Within the urogenital diaphragm between the bulb of the penis, the prostate and the rectum
Describe the course a sperm cell takes from production to ejaculation
Produced in seminiferous tubules then -> straight tubules / tubuli recti -> rete testes -> efferent ductules -> epididmis where it is stored.
Then on emission passes through vas deferens where it is joined by secretions of seminal vesicles just before entering urethra (prostatic -> membranous -> spongy), pooling in urethral bulb before exiting penis on ejaculation
Describe the contents of the spermatic cord
Genitofemoral nerve (genital branch) Testicular artery Cremasteric artery Artery to vas Paminiform plexus Vas deferens Lymphatics Processus vaginalis
Describe the coverings of the spermatic cord
Superficial fascia and skin
External spermatic fascia (derived from aponeurosis of external oblique muscle)
Cremasteric muscle and fascia (derived from transversalis and external oblique)
Internal spermatic fascia (derived from transversialis fascia)
What is a hydrocoele?
A usually painless accumulation of fluid in the tunica vaginalis - can be within spermatic cord or the testis
How can a haematocoele be distinguished from a hydrocoele?
Transillumination - shine torch through and haematocoele will be red, hydrocoele will be clear
What is the most common cause of epididymitis?
STI
What is a spermatocoele?
An epididymal cyst - generally painless accumulation of sperm and fluid that arises from the head of the epididymis
What would you be worried about in a patient with testicular torsion?
Necrosis
Describe the epithelium lining the epididymis
Pseudo-stratified columnar with sterocilia
Describe the cremasteric reflex
Elevation of testis on stroking superior medial thigh. This area is innervated by the ilioinguinal nerve whose genital branch innervates the cremaster muscle
Why can prostatic malignancies spread to the vertebrae and the brain?
Through the valveless internal venous plexus
Describe the structure and function of the epithelial cells lining the tubuli recti and rete testis
Columnar ciliated and simple cuboidal to absorb fluid and propel sperm along tube
What are the 4 layers of the vas deferens?
Epithelium + lamina propria
Inner and outer longitudinal smooth muscle
Middle circular smooth muscle
Describe the epidemiology of testicular tumours
High percentage of tumours seen in early life
Vast majority are germ cell tumours
What is the mesovarium?
A short peritoneal fold that suspends the ovaries
Where do the ovaries develop?
Within the mesonephric ridge on the posterior abdominal wall
What is the lymphatic drainage of the ovaries?
To the para-aortic nodes
What is the ovarian ligament?
The ligament attaching the ovary to the uterus, it is derived from the gubernaculum
What is the round ligament?
The ligament attaching the uterus to the labium majus, it is derived from the gubernaculum
Describe the blood supply to the ovaries.
From the ovarian arteries which are direct branches off the abdominal aorta
Describe the venous drainage of the ovaries
Left ovarian vein -> L renal vein
Right ovarian vein -> IVC
What is the suspensory ligament of the ovary?
The ligament that attaches the ovary to the wall of the pelvis and contains the ovarian vessels, lymphatics and nerves
Where would you find the Fallopian tubes?
Extending posterolaterally from the uterus to the pelvic walls before arching anteriorly and superiorly to the ovaries
Describe the parts of the Fallopian tubes
Fimbrae - finger like projections
Infundibulum - funnel shaped distal end of the tube that opens into peritoneal cavity
Ampulla - widest and longest part of the tube where fertilisation usually occurs
Isthmus - thick walled part of the tube that enters the uterus
Why is there a higher risk of peritonitis in females?
Because in females the peritoneal cavity is open via the ostium of the Fallopian tubes whereas in males the cavity is completely closed
Describe the blood supply to the Fallopian tubes
Anastomosis of the ovarian artery and the ascending branch of the uterine artery
Describe what happens to the endometrium at menstruation
Spiral arteries spasm, retract back into the deeper evoking ischeamia which leads to desquamation of the outer 2/3 and associated bleeding
What are the 3 layers of the endometrium in the secretory phase?
The compact superficial zone
Spongy middle zone
Inactive basal layer
What are the anterior and posterior relations to the uterus?
Anterior - uterovesical pouch
Posterior - rectouterine pouch (Pouch of Douglas)
How does the uterus develop?
The uterus is formed embryologically by the the Mullerian/paramesonephric ducts which grow to fuse in the midline
What are the 3 layers of the uterine wall?
Endometrium
Myometrium
Perimetrium
How is the uterus normally positioned?
Anteverted and anteplexed
What is the blood supply to the uterus?
Uterine artery from the internal iliac artery
With some anastomosing with the ovarian artery
Describe the venous drainage of the uterus
Uterine plexus draining into uterine veins
Where do the ureters run in relation to the uterus?
Laterally, under the uterine artery and vein (water under the bridge)
Describe the parts of the cervix
Internal os
Endocervical canal
External os
What type of epithelium lines the cervix?
Simple columnar with branched glandular cells
Stratified non-keratinised squamous on inner aspect of external os
How is cervical mucus different around the time of ovulation?
Has higher water content, is less acidic and higher in electrolytes, acellular clear and “stretchy”
What are Nabothian cysts?
Infected, blocked cervical glandular ducts
Explain the clinical consequence of Nabothian cysts
Can cause infertility by making vagina in hospitable to sperm
Where may pain likely to be felt by a patient with an ectopic pregnancy?
R or L iliac fossae
What ligaments support the uterus within the pelvic cavity?
The transverse cervical ligament (lateral stability)
The uterosacral ligaments (oppose anterior pull of round ligament)
Why can ectopic pregnancy often be misdiagnosed as appendicitis?
Resultant appendicitis
R iliac fossa pain
How would you examine the uterus?
Bimanual palpation - two fingers pressed superiorly into the vagina while the other hand is pressed inferoposterioirly in the pubic region anteriorly
What is endometriosis?
Presence of tissue resembling endometrial glands and stroma outside the uterine cavity, inducing a chronic inflammatory reaction
Where are the Bartholin glands located?
On each side of the vestibule near the vagina
When are the Bartholin glands palpable?
When they are infected
How does the presence of Lactobacillus protect the vagina from pathogens?
They utilise glycogen to produce which maintains a low pH
What is culdocentesis?
Medical procedure performed to extract accumulated fluid
Describe the innervation of the vagina
Inferior 1/5th somatic innervation from pudenal nerve
Superior 4/5ths uterovaginal plexus
What nerves supply the perineum?
Pudenal nerve (S2-4) and ilioinguinal nerve
Describe the anaesthetic options available for childbirth
Caudal epidural block - anaesthetic through indwelling cather in the spinal canal, affects S2-4, must be administered in advance of delivery
Pudenal nerve block - local anaesthesia for S2-4 dermatomes and inferior quarter of vagina
Spinal anaesthesia - Spinal needle of anaesthetic at L3-L4 level - complete motor and sensory anaesthesia below the waist so mother becomes totally reliant on electrical monitoring for sensation of uterine contractions
Describe and name the levator ani muscles
Puborectalis - from pubic symphysis looping around rectum
Pubococcygeus - from pubis to coccyx and sacrum
Iliococcygeus - ischial spine to sacrum and coccyx
Coccygeus - overlying sacrospinous ligament, ischial spines to lateral aspect of sacrum and coccyx
What is the clinical relevance of the superficial perineal pouch?
Site where urine collects if the urethra is ruptured below perineal membrane
Describe the layers of the urogenital triangle
Skin, Deep perineal fascia, Superficial perineal pouch, Perineal membrane, Transverse perineal muscle contained within Deep perineal pouch which also contains External urethral sphincter
What are the anatomical boundaries of the perineum?
Anterior – Pubic symphysis Laterally – Inferior pubic rami and inferior ischial rami, and the sacrotuberous ligament Posterior– The tip of the coccyx Roof – The pelvic floor Base – Skin and fascia
Describe the blood supply of the pelvic floor
Internal pudenal artery
What is the innervation of the pelvic floor and the spinal roots of this?
Pudenal nerve
S2,3&4 (keeps your guts off the floor)
What is the perineal body?
Fibromuscular node at the centre of the perineum at the junction of the anterior and posterior perineum that functions as a point of attachment for the muscle fibres of the pelvic floor
What is an episiotomy?
Surgical cut to the perineum
How can childbirth damage the pelvic floor?
Stretching of the pudenal nerve leading to neuropraxia and muscle weakness
Stretching and damage of pelvic floor and perineal muscles leading to muscle weakness
Stretching and damage of ligaments of pelvic floor leading to ineffective muscle action
What are the surgical treatments for incontinence?
Colposuspension
Tension free vaginal tape
Name the organism that causes genital chlamydia
Chlamydia trachomatis, generally serotypes D-K
Where would you look up up-to-date advice for STI management?
BASHH Guidelines
Which strains of HPV cause cutaneous mucosal and anogenital warts?
HPV 6 and 11
How would you treat cutaneous mucosal and/or anogenital warts?
Conservatively - majority resolve spontaneously
Otherwise topical podophyllin, cryrotherapy, intralesional interferon, imiquimod or surgery
Specifically, what type of organism causes chlamydia?
Obligate intracellular bacterium
What are the signs and symptoms of genital chlamydia?
Typically no symptoms!!
Urethritis
Prostatitis (men), procticitis (MSM)
Cervicitis, salpingitis, perihepatitis (women)
How is chlamydia diagnosed?
Endocervical or urethral swabs (if refused, first pass urine sample) subjected to nucleic acid amplification techniques
Consider dual testing with N. gonorrhoae
How would you treat chlamydia?
Azithromycin (single dose or few days course)
Which strain of herpes simplex virus is associated with genital herpes?
HSV2
How is genital herpes different from genital warts?
Herpes, unlike warts is typically painful, can cause genital ulceration and inguinal lymphadenopathy
Explain why recurrent herpes infections can occur
Latent infection in dorsal root ganglia
How would you diagnose herpes?
PCR of vesicle fluid and/or ulcer base
How would you treat herpes?
Aciclovir and advice on barrier contraception to reduce transmission risk
Which strains of HPV are strongly associated with cervical and anogenital cancer?
16 and 18