Reproductive System Flashcards
What are the components of the male reproductive system?
Testes Epididymis Ductus deferens Accessory glands Urethra Penis
Describe how testes move into the scrotum
Develop in abdomen at level of kidneys
Migrate through hole in abdominal wall/inguinal canal into scrotum around time of birth, carrying spermatic cord and some fascia to cover sac
Descent is guided by gubernaculum
What is in the spermatic cord?
Blood vessels
Nerves
Ductus deferens
What is the risk of leaving testes undescended?
Germ cell tumours
Where is sperm produced in the testes?
Seminiferous tubules
Describe the structure of mature sperm
Head- streamlined, acrosome head with enzymes to penetrate ovum, nucleus with highly condensed chromosomes
Midpiece- lots of mitochondria
Tail- flagellum for propulsive forward swimming
What is the role of the epididymis?
Collect sperm from seminiferous tubules to mature, store, concentrate and transport sperm
What causes sperm maturation in the epidiymis?
Maturation factors
How long does it take for sperm to move through the epididymis?
12-14 days
Why is thermoregulation of the testes important?
Allow normal function and production of sperm
How are the testes thermoregulated?
Pampiniform plexus, small network of veins
What is the role of the ductus deferens?
Transport sperm from epididymis to urethra
What are the walls of the the ductus deferens made of and why?
Thick smooth muscle
Contract to propel sperm movement
What is the pathway of the structures the ductus deferens passes through?
Inguinal canal
Abdomen
Around bladder
Accessory sex glands
What is the role of the urethra?
Carry ejaculate and urine from base of bladder to external urethral opening
What is the lining of the urethra?
Urothelium
What are the parts of the urethra?
Prostatic- passes through prostate
Membranous- passes through perineal membrane
Spongy/penile- runs through penis
What is the perineal membrane?
Divides pelvic area from whats below and provides attachment for external genitalia
List the accessory sex organs
Ampulla Seminal vesicles Prostate Vagina Bulbourethral glands
What is the role of the accessory sex glands?
Make up seminal fluid part of semen
Where are the ampulla located and what do they produce?
Dilated distal ends of the ductus deferens
Minor amounts of seminal fluid
What does seminal vesicles fluid contain?
Fructose- energy
Fibrinogen- coagulation
Enzymes
Where are the seminal vesicles located?
Connected to ductus deferens to form short ejaculatory duct whihc joins the urethra
Describe the secretions of the prostate glands
Thin and milky
What does prostate secretions contain?
Buffers- acidic urethra and vagina
Clotting factors- act on fibrinogen to coagulate
What is the role of bulbourethral glands?
Produce small amounts of clear pre ejaculatory fluid to help flush urethra before ejaculate comes through
Where are the bulbourethral glands located?
Level of perineal membrane
Describe the process of ejactulation
Sympathetic mediated contraction of ductus deferens walls
Sperm propelled to combine with secretions from accessory glands
Joins ejaculatory duct then enters urethra at seminal colliculus
Prostate contractions help release prostatic secretions
Powerful somatic urethral contractions propel semen out of the body
What are the two stages of ejaculation?
Seminal emission
Ejaculatory phase
What are the different parts of the penis?
Root- attached to perineal membrane and partly to crura
Body- two crura running side by side
Glans- swollen distal end, contains external urethral orifice for passage of semen
What are the two types of erectile penile tissue?
Corpora cavernosa- paired cavernous bodies, main erectile tissue attached to perineal membrane
Corpora spongiosum- surrounds urethra forming bulb which joins perineal membrane and forms glans
What and where are the vessels in the penis?
Dorsal artery, deep artery and artery of bulb branching off internal pudendal artery, branch of internal iliac artery
Found dorsal to corpus spongiosum
How does testicular orientation vary between species?
Horizontal- cats
Vertical- bull, ram, humans
Diagonal- dogs, boar, stallion
Snakes- internal
How do bulbourethral glands vary between species?
Dog- none
Ox- small
Pig- long and vertical
Horse- long and diagonal
What is the gland equivalent to humans seminal vesicles?
Vesicular glands
What are the two types of penis?
Musculocavernous
Fibroelastic
Describe a musculocavernous penis and name species with this type
Flaccid when not in use
Engorges with blood to become erect
Man, horse, dog, cat
Describe the fibroelastic penis and name species with this type
Solid structure that elongates due to relaxation of retractor penis muscle allowing sigmoid flexure to straighten
Ox, boar, ram
Name the components of the female reproductive system
Ovaries Uterus Vagina Cervix Uterine tube External genitalia
What does the ovarian ligament connect together?
Uterus to ovaries
What is the role of the ovaries?
Oogenesis/egg maturation
Hormone production to maintain structures linings
Describe the structure of the human ovaries
Tunica albuginea- fibrous outer coat
Outer cortex- contains follicles and reserve of eggs
Primordial- reserve follicles
Inner medulla- contains vessels and nerves
Maturing and matured follicles
What does the broad ligament connect together?
Ovary to uterine tube
What supplies uterine tube with blood vessels?
Suspensory ligament
What are the regions and roles of the uterine tube?
Infundibulum- finger like fimbriae to collect ova and waft down tube by cilia and peristalsis
Ampulla- wider, site of fertilisation
Isthmus- join uterus, narrowed part of tube
What is the role of the uterus?
Implantation and pregnancy, shedding lining when no pregnancy established
What causes the uterus lining to be shed?
Declining levels of progesterone
Describe the structure of the uterus
Fundus- uterine tubes enter
Body- bulk of uterus, site of implantation
Cervix- external os, barrier between uterus and vagina
What are the uterus walls made of?
Thick smooth muscle lined with endometrium which thickens for implantation
What is the cervix made of?
Collagenous dense smooth muscles lined with squamous epithelium
What are the different shaped cervixes?
Nulliparous- circle shaped
Parous- slit shaped after vaginal birth
What is the function of the cervical canal?
Secrete mucus, kept thick by progesterone to maintain a barrier and made thin by oestrogen to allow sperm to penetrate
What is the normal position of the uterus?
Anteflexed and anteverted
What holds the uterus in position?
Round ligament
What is the structure of the vagina?
Distensible smooth muscle walls to allow expansion, lined with stratified squamous non-keratinised epithelium
Small glands present for secretion of lubricant
What is the role of the vagina?
Copulation
Passage of menses
Birth canal
Describe the female erectile body
Clitoris, female homologue of penis
Bulb surrounding vestibule
What is the blood supply to the female reproductive system?
Ovarian artery branching off aorta from L2 anastomoses with uterine and vaginal arteries from internal iliac artery
Explain the different locations of follicles in ovaries of different species
Most species have cortical follicles which burst on external surface when mature
Horses- follicles are in the medulla and empty in ovarian fossa
Birds and reptiles- only one functional ovary comprised of a cluster of follicles
Define ovarian fossa
Depression in medial border of ovary
What are the different types of uteruses and what species have them?
Simplex- one cervix, large uterine body with no horns, humans
Bicornuate- one cervix, small uterine body with long horns, dogs, pigs, horses, sheep
Duplex- 2 cervixes, separate horns, no uterine body, rats, rabbits
Define vestibule
Common opening for urogenital systems
Describe the uterine tube in egg laying species
Infundibulum- collects yolk, fertilisation site Magnum- albumen production Isthmus- form shell membranes Uterus- form shell and incubates Vagina- muscular to aid laying
What cells are present in seminiferous tubules?
Leydig cells- in surrounding connective tissue to produce testosterone
Steroli cells- support developing germ cells to form syncytium by providing correct environment for sperm development
Germ cells- mature as move into lumen, line epithelium
What is in the lumen of the seminiferous tubules?
Fluid containing mature haploid cells
What are the different regions of the epididymus?
Head- efferent ductules
Tail- duct of epididymis
Define oogenesis
Egg maturation
Define folliculogenesis
Follicle maturation including the egg
Describe the walls of the uterine tube
Outer longitudinal and inner circular smooth muscle lined with ciliated columnar epithelium
Secretory cells present for nourishment
What are the layers of the uterus?
Perimetrium- peritoneum covering outer surface
Myometrium- 3 thick smooth muscle layers
Endometrium- innermost layer, vascular and glandular
What is meant by sexual differentiation?
Duct/genital, neuroendocrine and behavioural sex
What are the different periods for fetal development and sexual differentiation?
Preembryonic- indifferent gonadal differentiation for first 3 weeks
Embryonic- weeks 3-8 with differentiation beginning at week 5
Fetal period- weeks 9 onwards, growth and development of foetus
Describe genotypic sex
Determined by chromosomes at conception
What is meant by the early embryonic gonads being bipotential?
Gonadal ridge is able to develop into male and female reproductive tracts
What is the genetic factor that determines sex?
Presence of SRY protein transcription factor on Y chromosome which is testis determining factor
How is gonadal sex formed?
Primordial germ cells at week 5 migrate from yolk sac to genital ridge to become oocytes or spermatazoa
SRY forms testes, absence forms ovaries
Describe how male gonads form
Testosterone present
Paramesonephric duct regressed due to antimullanarian hormone
By week 8 mesonephric duct forms male tract
Describe how female gonads form
Paramesonephric duct differentiates
Primary sex cords breakdown
Secondary sex cords become follicles
At week 9 paramesonephric ducts give rise to female tract
What is present in the indifferent gonads?
Mesonephric duct
Paramesonephric duct
Proliferating sex cords
What hormone causes the formation of the penis?
Dihydrotestosterone
What is the role of testosterone for male reproductive development?
From leydig cells
Stimulate mesonephric ducts to form epididymis, ductus deferens and seminal vesicles
What does the absence of antimullerian hormone do in female reproductive tract development?
Develops paramesonephric ducts which form upper vagina, uterus and oviducts
Where do the different parts of the female reproductive tract develop from?
Uterus- fusion of paramesonephric ducts
Lower vagina- urogenital sinus
What is the role of hormonal sex?
Influences neuroendocrine and brain sex and behaviour
How is hormonal sex determined?
Testis- high androgen levels
Ovary- high oestrogen levels
How do hormones influence sex specific behaviours?
Expression of hormone receptors in the brain
Where does the hypogastric nerve originate and what does it innervate?
Caudal mesenteric ganglia
Sympathetic innervation to pelvic viscera causing penis to stay flaccid as contracts vessels/retractor muscle
What is the role of pelvic nerve?
Parasympathetic innervation to pelvic viscera
What is the role of the pudendal nerve?
Somatic innervation to pelvic viscera, external genitalia and external sphincters
What somatic pelvic nerves are also present in cows?
Obturator nerve- supply abductor muscles of hind limb
Sciatic nerve- supplies hind limb
Caudal rectal nerve- branch of pudendal nerve, supplies pelvic diaphragm muscles and external anal sphincter
What are the main arteries that supply the lower human body?
Common iliac arteries branch off aorta
External iliac artery- lower limbs and anterior abdominal walls
Femoral artery- lower limbs
Internal iliac- pelvic viscera, branches into umbilical, internal pudendal, prostatic/vaginal
What are the main nerves that supply the human lower body?
Branches of lumbosacral plexus
Femoral nerve- anterior thigh, knee extension
Obturator nerve- medial compartment of thigh, hip adduction
Pudendal nerve- skin around genitalia, motor control of sphincters
Sciatic nerve- motor and sensory innervation to lower limb
Explain how pregnancy effects the abdominal organs
Moves some up and back
Bladder compressed
Progesterone slows digestion
What are general effects of pregnancy on the body?
Restricted venous return- varicose veins and oedema
Increased melanin production- melasma due to increased pigmentation
Relaxin produced at end of pregnancy- loosens joints and ligaments, particularly sacroiliac joint for birth canal and softens cervix
What are mammary glands and what type of secretion do they do?
Modified enlarged sweat glands that carry out apocrine secretion
What is the structure of mammary glands walls?
Cuboidal epithelium surrounded by myoepithelium
How do mammary glands change with pregnancy and puberty?
Pregnancy- rapidly proliferate to enlarge and form alveoli, later secreting secretory material
Puberty- enlarge with adipose and connective tissue
What is the purpose of the areolar glands?
Lubricate and protect the nipple
How does domestic species mammary glands drain?
Lobes Lactiferous duct Gland sinus Teat sinus Teat
What is the purpose of the narrowing of each sinus in the teat?
Contains smooth muscle, which open on suckling
What are the hormonal changes when fertilised egg implants?
Egg produces human chorionic gonadotropin which maintains corpus luteum
Corpus luteum continues to produce oestrogen and progesterone until placenta established
High progesterone also prevents further ovulation
What happens to the uterus lining in the oestrus cycle when there is no implantation?
Reabsorbed
What is the different between menses and oestrus?
Menses- shedding of endometrium
Oestrus- period of sexual activity
Define seasonal monoestrus and name a species with this cycle
1 period of sexual activity during a season at one time of year
Fox
Define dioestrus and name a species with this cycle
Go into oestrus twice a year
Dog
Define polyoestrus and name a species with this cycle
Succession of oestrus cycles during the year
Cat
Cow
Define seasonal polyoestrus and name species with this cycle
Succession of oestrus cycles during certain time of year
Sheep
What organs are bypassed in foetal circulation?
Liver
Lungs
What supplies oxygen rich blood to the foetus?
Placenta via the umbilical veins
What happens to the blood supply to the foetus at birth?
First breath causes pulmonary vessels to open and pulmonary circulation takes over
What is the role of the umbilical vein and what does it become after birth?
Oxygenated blood from placenta to liver
Teres ligament covered by falciform ligament
What is the role of paired umbilical arteries and what do they do after birth?
Deoxygenated blood from aorta to placenta
Proximal ends stay open to supply bladder, distal ends close
What is the role of ductus venosus and what does it become after birth?
Connects umbilical vein to caudal vena cava allowing oxygenated blood to bypass the liver
Ligamentum venosum
What is the role of the foramen ovale and what does it become after birth?
Allows oxygenated blood to go straight from right to left atrium
Closes to become fossa ovalis
What is the role of the ductus arteriosis and what does it become after birth?
Allows blood to bypass the lungs, connecting pulmonary trunk to aorta
Closes to become ligamentum arteriosum
Why may IUDs be used in cattle?
Sync breeding cycles in a herd
How do hormonal contraceptives work?
Increase oestrogen and progesterone so low LH and FSH, causing thick cervical mucus and thin endometrium
What are fetal membranes and list the 4 membranes?
Structures developed from fertilised ovum that dont form part of the embryo Amnion Chorion Allantosis Yolk sac
Where does the placenta develop?
Where blastocyst implants from chorion and maternal endometrium
Define decidua
Part of endometrium involved in placenta
How are the amniotic and chorionic cavity related in human pregnancy?
As amniotic cavity increases, chorionic decreases causing them to fuse
What are the different types of placenta and what species have them?
Diffuse- villi scattered over whole chorion, horses, pigs
Zonary- placenta forms complete or incomplete band around foetus, dogs, cats
Discoid- part of chorion smooth and other parts interact with enometruim to form placenta, humans
Cotyledonary- villi grouped in balls seperated by regions of smooth chorion, ruminants
Define caruncle
Oval thickenings of uterine mucosa resulting from proliferation of sub epithelial connective tissue, only site to attach fetal membranes
Define choleydons
Transmit fetal blood and allow exchange with maternal blood
Where are the different fetal membranes found?
Yolk sac- some taken in to form gut tube, external parts form choriovitelline placenta
Amnion- surrounds embryo, attached at ubilicus
Chorion- associated with endometrium, villi project to bring fetal and maternal blood close
Allantoic- outgrowth of hindgut, part connected to chorion forms chorioallantoic placenta
What is the positioning of the allantoic membrane in dogs and horses?
Totally surrounds amnion so only chorioallantoic connections exist
Born totally enclosed in amnion
Chorioallantoic membrane reabsorbed after birth
What is the positioning of allantoic membrane in ruminants and pigs
Connected to chorion so amniotic membrane ruptures for birth
List the drainage from mammary glands
Lobule Interlobular ducts Lactiferous sinus Lactiferous duct Pore in nipple
