Reproduction Flashcards
Which structure are included in the male reproductive system?
Penis Scrotum Testes Epididymis Vas deferens Prostate Seminal vesicles
What is the function of the epididymis?
Transports and stores spermatozoa that are produced by the testes, stimulates maturation process of sperm
How does sperm enter the vas deferens from the epididymis?
Sexual arousal, contractions force the sperm into the vas deferens
Describe the location of the epididymis?
Long coiled tube that resides on the posterior surface of each individual testicle
What is the Vas deferens?
Muscular tube that travels from the epididymis into the pelvic cavity posterior to the bladder, transporters MATURE sperm to the URETHRA in preparation for ejaculation
Where is the spermatic cord formed?
Formed at the deep inguinal ring
What is found within the spermatic cord?
Testicular artery, pampiniform plexus, autonomic and GF nerve, lymph vessels.
What is the function of the bulbourethral gland?
Glands produce a transparent lubricating fluid that empties directly into the urethral glands. Fluid lubricates the urethra and neutralises residual acidity
Where is the bulbourethral gland located?
Laterally besides the urethra, inferior to the prostate gland
What is the function of the testes?
Responsible for the synthesis of testosterone by Ledydig cells, in response to LH.
Site of spermatogenesis
Which cells produce testosterone?
Leydig cells
Which coiled masses of tubes are encapsulated by the testes?
Seminiferous tubules
Why do the testes side outside the body?
Regulates optimum temperature to facilitate spermatogenesis
What are seminal vesicles?
Sac like capsules that attach to the vas deferens besides the base of the bladder
Seminal vesicles produce seminal fluid that provides sperm with a source of energy to facilitate movement
Where are the seminal vesicles located?
Attach to the vas deferens besides the base of the bladder
What does seminal fluid contain?
Fructose, citric acid, bicarbonate, fibrinogen, fibrinolytic enzymes
What is the function of seminal fluid?
neutralises the acidic environment
Fibrinolytic enzymes enable passage of sperm (Prevents clot formation)
Nourishes sperm
What are the two functional parts of the testes?
The seminiferous tubules and leydig cells.
Where is the main site of spermatogenesis within the testes?
Seminferous tubules
Which two cell types are present within the seminiferous tubules?
Sertoli cells Germ cells (spermatogonia)
What is the function of Sertoli cells?
Provide nutritional and hormonal support to facilitate development of spermatogonia into spermatozoa
Secretes activin, inhibin and ABP
What structure arises from the seminiferous tubules?
Epididymis
Where do leydig cells reside?
Between the seminiferous tubules
Which hormone activates and binds onto Leydig cells?
Lutenising hormone (LH)
Which is the primary artery that supplies the testes?
Left /right testicular artery arises from the aorta
Which artery supplies the vas deferent?
Internal iliac artery
What is the lymphatic drainage of the testes?
Para-aortic lymph nodes
Which nervous supply controls ejaculation?
Sympathetic
Which nervous supply controls erection?
Parasympathetic
Which neural supply innervates the vas deferens?
Parasympathetic
Which vasodilator is released from parasympathetic innervation of the vas deferns?
Nitric oxide
What effect does nitric oxide release have on the Vas Deferens?
Smooth muscle relaxation in the penile arteries, and closure of venous outflow from venous
What is the term for erectile tissue?
Corpus cavernous
muscles help sustain the erection, contact in the penis to prevent blood flow to the tissue during reversal
What is the corpus spongiosum?
During erection to prevent urethra from pinching closed. Maintains the urethra as a viable channel for ejaculation
Remains pliable during erection, whilst the corpora cavernous penis becomes engorged with blood
Which cavity are the ovaries located within?
Peritoneal cavity
Where does fertilisation occur?
Ampulla
How is the uterus supported?
Supported by the tone of the pelvic floor (elevator ani & coccyges), and ligaments *Broad, round and uterosacral)
Where does the corpus of the uterus open into?
Opens into the vagina
Why does the corpus has the ability to expand?
Expands to hold a developing baby
Where does the sperm and menstrual blood leave the female reproductive tract?
Channel through the cervix
Where is the site of oogenesis?
Ovaries
What does the vagina connect?
Canal that connects the cervix to the external body surface
What is the function of lactobacillus in the vagina?
In response to oestrogen, epithelial cells convert glycogens to lactic acid (Reduces infection) pH <4.5
What is the function of the fallopian tubes?
Provides a passage for the ova to travel from the ovaries to the uterus
Where does conception typically occur within the female reproductive tract?
Fallopian tubes
Where does implantation of a fertilised egg occur?
Within the uterus lining
What is the function of fimbria?
Capture the released secondary oocysts from the ovaries, cilia and spiral muscles stimulate the movement of the oocyte to the central components
What is an ectopic pregnancy?
Occurs whereby the fertilised egg is implanted elsewhere from the uterus
Which uterine layer lines the uterus?
Endometrium
What is the function of the endometrium lining?
Specialised layer of epithelial mucous membrane, lining the uterus thickens during the mensural cycle in preparation for embryo implantation
What effect does a progesterone reduction have on the endometrium?
Reduction in progesterone causes shedding of the endometrium lining stimulated by ischaemia and necrosis, vasoconstriction of arterioles causes reduction of blood flow
Which artery supplies the ovaries?
Ovarian arteries branched from the aorta
Which artery supplies the uterus, vagina?
Uterine arteries derived from the internal iliac artery
What is the lymphatic drainage of the ovaries?
Para-aortic
Which hormone influences the secretion of cervical mucous?
Luteinising hormone
What is the function of cervical mucous?
Prevents pathogenic entry, in addition to facilitate the transport of sperm towards the Fallopian tubes.
Where is a smear test conducted from?
Cells taken from the external os.
What phase are primary oocytes in pre-puberty?
Prophase 1
What happens to primordial follicles as age progresses?
Undergoes atresia
Where are diploid spermatogonia produced?
Edge of the somniferous tubules in the testis, undergoing mitosis and meiosis to produce haploid spermatids
During meiosis what is the fate of primary spermatocytes?
Primary spermatocytes divide to form haploid secondary spermatocytes
What is the fate of secondary spermatocytes?
During meiosis II, haploid secondary spermatocytes divide during meiosis II to form spermatids
Which receptors are located on Leydig cells?
LH receptors
Why is the cytoplasm of leydig cells pale?
Attributed to cholesterol content
What effect does LH on Leydig cells?
Stimulate testosterone synthesis
Binds to specific G protein coupled receptors, linked to adenyl cyclase, increasing cAMP production. StAR protein transporting cholesterol to inner mitochondria membrane to initiate steroidgenesis
What is the function of the StAR protein?
Transpors cholesterol to the inner mitochondrial membrane to initiate steroid genesis
What feedback loop does testosterone stimulate?
Negative feedback inhibition of the hypothalamo-pituitary-testicular axis
Inhibits LH secretion from gonadotrophs within the anterior pituitary
What is the function of androstenedione?
Enhances the production of testosterone
What is DHEA?
Bio intermediate for androgen and oestrogen sex steroids
How are androgens converted into oestrogens?
Aromatisiation
Androgens can be aromatised by aromatase enzyme into oestrogens
Which cells secrete testosterone?
Leydig cells
Which cells stimulate spermatogenesis?
Sertoli cells
Which factors act on Sertoli cells?
FSH
testosterone
What regulatory peptide hormones are secreted by Sertoli cells?
Activin and inhibin
Where are Sertoli cells located?
Within the seminiferous tubules
What are the four main functions of Sertoli cells?
1) Assists movement of spermatogonia to tubular lumen
2) Transfer nutrients from capillaries to developing germ cells
3) phagocytosis of damaged germ cells
4) Secretion now nutrients and hormonal support to facilitate development of spermatogonia into spermatozoa
What is the function of activin?
Stimulates GnRH & FSH secretion
What is the function of inhibit?
Inhibits FSH secretion (Acts on the anterior pituitary gland
What protein is formed by Sertoli cells upon activation of FSH?
Produce androgen binding protein (ABP).
What is the function of androgen binding protein?
Protein binds testosterone and helps maintain a high concentration of the hormone within the testes, essential for triggering spermatogenesis.
Which hormone prevents the formation of Fallopian tube development in male foetus?
Anti-mullerian hormone (AMH)
Which types of junctions form a blood testis barrier?
Tight junctions
What is the function of the blood-testis barrier?
Protecting sperm from immune reactions.
Spermatogonia move into the Sertoli cells, enclosed within the cytoplasm, the site of spermatogenesis.
Where is oogenesis initiated?
It is initiated within the ovaries
Where are Graffian follicles embedded?
Ovarian stroma
What are the function of theca cells (external layer)?
Secrete androgens, aromatase converts into oestrogens.
What is sexual reproductioN?
Sexual reproduction involves the fusion of gametes from two parents, this introduces genetic variation as it involves the mixture of paternal and maternal genes, which have already been assisted during crossing over and independent assortment. It involves fertilisation to produce a diploid zygote.
What are the two mammalian gametes?
Spermatoozoon
Ovum
What is gametogenesis?
Gametogenesis is the production of gametes, this occurs in the gonads. Female gonads are known as the ovaries, whereas male gonads are known as the testes.
What is spermatogenesis?
involves the production of spermatozoa in males, whereas oogenesis involves the production of ovum.
What are the 3 phases of gametogenesis?
3 phases. Multiplication, growth and maturation.
Where do diploid oogonia derive from?
Derive from foetal epithelial tissue
What are primary oocytes encapsulated by?
Primordial follicles
Which cells surrounded the primordial follicles of the primary oocytes?
Granulosa cells
What happens to dormant primordial follicles?
They undergo atresia
Which hormones stimulate the development of the primordial follicles?
FSH
What effect to hormonal control have on the primary follicles?
The primary oocyte develops a zone pellucida, develops into a secondary follicles, containing additional layers of granulosa cells which are surrounded by a theca
Which is the final ovarian follicle?
Graafian follicles
What is the antrum?
A fluid filled cavity between the granulosa cells
What is the product of the first meiotic division of a primary oocyte?
Secondary oocyte
Polar body
What phase are secondary oocytes in during ovulation?
Metaphase II
Post-ovulation what happens to the remains of the ovarian follicle?
Ovarian follicle develops into a corpus luteum (contains hormone secreting cells)
Which hormone is secreted by the corpus luteum?
Progesterone, maintains endometrium for implantation
What happens if the secondary oocyte is not fertilised?
The corpus luteum degenerates
What are theca cells?
Associated with the external layer of the ovarian follicles
What is the function of theca cells?
Supports folliculogenesis, structural and nutritional support of developing follicle; hormone synthesis; LH stimulates synthesis of androgens
What does the overactivity of the theca cells result in?
Elevated androgen levels (PCOS)
Polycystic ovarian syndrome
What are granulosa cells?
Associated with the internal layer of ovarian follicles
What is the function of granulosa cells?
Hormone synthesis, FSH and androgens stimulate aromatase to convert androgens to the production of estradiol.
Secretion of inhibin (inhibits FSH secretion)
Secretion of activin: Elevated concentrations of activin are produced by the endometrium, have a role in the development of the endometrium during the mensural cycle.
How can activin be used as an indicator?
Used as a prognostic indicator in women undergoing treatment to stimulate ovulation.
What is the luteal phase?
Granulosa lutein cells produce progesterone (Negative feedback promote pregnancy by maintain endometrium)
Relaxin stimulates follicular development and oocyte maturation and helps endometrium prepare for pregnancy and softens pelvic ligaments for childbirth.
What effect does relaxin have?
Stimulates follicular development and oocyte maturation
Which hormone stimulates LH and FSH secretion from gonadotrophs?
Gonadotrophin releasing hormone (GnRH)
Where is GnRH released?
Into the primary capillary plexus within the median eminence, enters into the hypophyseal-portal circulation, delivered to the anterior pituitary via the secondary capillary plexus
Which gonadtrophins are released from gonadotrophs?
LH and FSH
What are the LH target cells?
Leydig cells, theca cells
What are the FSH target cells?
Granulosa cells and Sertoli cells
Which neurones edit the feedback mechanism?
Kisspeptin neurones
What is released from kisspeptin?
kisspeptin
In what manner is Kisspeptin released?
Pulsatile manner
Where does kisspeptin effect?
Direct effect on hypothalamic neurones, secreting GnRH in a pulsatile manner, determines output of gonadtrophins
Which hormone inhibits hypothalamic kisspeptin neurones?
Prolactin
Why are prolactin levels elevated?
Adenoma
Increased production from lactotrophs within the anterior pituitary gland
What effect does prolactin have on kisspeptin neurones?
Prolactin binds to prolactin receptors, inhibits kisspeptin release, reduction in pulsatility and stimulation of GnRH release, causing a downstream inhibition on LH and FSH, oestrogen and androgens
What are the effects of kissppetin inhibition?
Oligo-amenorrhoea
Low libido
Infertility
Osteoporosis
What does the menstrual cycle begin with?
Shedding of the endometrium
What happens during days 1-v?
Endometrial lining of the uterus undergoes necrosis due to ischaemia attributed to vasoconstriction of supplying vasculature as a result in the reduction of progesterone.
The shedding of the endometrium is associated with vaginal bleeding.
What is dysmenorrhea?
Painful abdominal cramps, vasospasm due to elevated levels of prostaglandins release from endometrium
What phase succeeds the menstrual phase?
Follicular phase
Which hormone is secreted by the follicle during the follicular phase before ovulation?
Oestrogen
What effect does oestrogen have on the endometrium?
Endometrium proliferation, developing a rich vasculature
Decidualisation of the endometrium
What happens to follicles during the early follicular phase?
selected to undergo final stages of maturation within the ovary prior to release of the secondary oocyte from the Graafian follicle.
Which hormone do the follicles release?
17B-Oestradiol
What effect does 17b-oestradiol exert?
Exerts a negative feedback effect on gonadotrophin secretion.
What happens to the non-dominant chosen follicles?
Undergoes atresia
What hormones does the dominant follicle release?
Oestrogen
Which cells within the follicles release oestrogen?
Granulosa cells, from gonadotrophin stimulation
How long does oestrogen exert a positive feedback for LH and FSH?
36 hours
What occurs due to the release of oestrogen from the Graafian follicle?
LH surge
What does the LH surge cause?
Stimulates ovulation
How does the LH surge cause ovulation?
Release prostaglandins, and inflammatory cytokines, leads to rupture of the stroll cells, and the germinal epithelium of the ovary, oocyte is released from the Graafian follicle
What happens post ovulation to the Graafian follicle?
Graafian follicle becomes into corpus luteum
What does the corpus luteum release?
Large amounts of progesterone
17-b oestradiol
What phase succeeds the follicular phase?
Luteal phase
Which hormone is dominant during the luteal phase?
Progesterone
What effect does oestrogen and progesterone have on gondotrophins during the luteal phase?
Negative feedback , decreases gonadotrophin
If fertilisation does not occur, what happens to the oestrogen and progesterone levels?
Decline due to corpus luteum disintegration
What is menstruation?
Vasospasm
Necrosis of tissue and contraction of uterine muscle, loss of tissue with blood
Reduction in oestrogen and progesterone decreases negative feedback, thus FSH levels begin to rise, initiating the cycle
How is the body temperature affected during menstrual cycle?
Increases by 0.5
Why does the body temperature increase by 0.5 after ovulation?
Due to progesterone
What 3 phases form the ovarian cycle?
Follicular phase
Ovulation
Luteal phase
What 3 phases form the uterine cycle?
Menstrual phase
Proliferative phase
Secretory phase
How do spermatozoan undergo functional maturation during fertilisation?
Under capacitation
What happens to the spermatozoan during capacitation?
Changes occur via the sperm cell membrane in which the receptors become available through the removal of a glycoprotein layer.
Acrosomal cap alterations in order to enable acrosome reaction
Motility changes
What motility changes occur to sperm during capacitation?
Discharing whipping movements of the tail in addition to large sideways swimming movement of the head occur
Designated as hyperactibity
Activation of the vigorous and asymmetric movement of the flagella upon leaving the epididymis
What does the capacitated spermatozoon penetrate?
Penetrates the cumulus oophorous of the ovum, binds to zone pellucida wit its plasma membrane intact
What happens during zone pellucida binding with acrosome?
Acrosome reaction proceeds, required for fertilisation
What hormone facilitates the changes for capacitation?
Oestrogen
Which cation causes hyperactivity of sperm?
Increase is Ca2+ permeability, causing a calcium influx. Therefore, this produces an increased intracellular cAMP levels, thus causing hyperactivation.
What is the acrosome reaction?
Penetration of corona radiata
Digestion of zone pellucida via acrosin
IZUMOI protein exposed on sperm binds to oocyte Juno, once bound, sperm and egg fuse.
Which protein induces the acrosome reaction?
Zona pellucid protein 3 (ZP3)
Where within he fallopian tube does the acrosome reaction proceed?
Within the ampulla
How does the acrosome bind to the zone pellucida?
Glycoproteins on the external surface of the sperm bind with the interactive glycoproteins on the zone pellucida of the ovum
Which enzyme digests the cumulus cells surrounding the oocyte?
Hyaluronidase
What are cumulus cells?
Cumulus cells are embedded in hyaluronic acid, and developed in the ovary with the ovum.
Which enzyme digests the zone pellucida?
Acrosin
How does membrane fusion occur between the sperm and oocyte?
Contents of the head depress into the egg. Zp3 binds to transferase receptors on the sperm, zone pellucida released calcium granules to prevent additional sperm from binding
Which sperm protein binds to oocyte JUNO protein?
IZUMO 1 protein
What is formed upon fusion of sperm and secondary oocyte nuclei?
Two pronuclei
Which hormone stimulates calcium ion influx into the spermatozoan?
progesterone
What happens to the chromosomes of the secondary oocyte during fertilisation?
Meiosis II is complete, formning a haploid nucleus
+ polar body
What happens to the polarity of ovum during fertilisation?
Polarity is reversed. Ion channels in the cell membrane open, causing the cell to become positive with respect to the outside, blocking entrance of further sperm
What is the cortical reaction?
Specialised lysosomes called cortical granules are released into the zone pellucida, causing protein molecules in the zone pellucid to change, altering the structure, to prevent further penetration (fertilisation membrane forms)
Which part of the diploid zygote develops into embryo and the amnion?
Inner cell mass
Which part of the zygote forms the placenta?
Trophoblast
Describe the potency of the inner cell mass cells?
Pluripotent
How does the blastocyst receive nutrients?
Once implanted, receives nutrients from the endometrium
How does the blastocyst attach itself to the endometrium?
The microbial on the surface of the outermost trophoblast cells interact with the uterine epithelial cells
Adhesion of the blastocyst on the endometrium arises through cell surface glycoproteins
Which factor is released from endometrial cells that stimulates adhesion of blastocyst?
Leukaemia inhibitory factor (LIF)
Which interleukin is released into uterine fluid?
Interleukin-11
What is the effect of elevated progesterone levels on the endometrium>?
Elevated levels of progesterone initiate molecular changes. Process triggers influx of decidual leukocytes. The changes in the endometrial stromal cells result in the endometrium developing a secretory lining, secreting various cytokines and growth factors. Secreted factors regulate the invasiveness of the trophoblast cells.
What is hCG?
Dominant hormone, human chorionic gonadotrophin
What is the function of hCG?
Essential for maintaining luteal function and preventing regression of the corpus luteum.
Which part of the zygote secretes progesterone?
Trophoblasts
What effect does hCG have on LH & FSH?
Exerts negative feedback
What is the purpose of placental secretion of progesterone?
Maintains the myometrium
What is the function of the myometrium?
Muscular lining of the uterus
Relaxed state: Prevents contractions and expulsion of the foetus
Inhibition of oxytocin receptor expression
What is placental lactogen?
Stimulates breast development during pregnancy
Which maternal hormones increase during pregnancy?
ACTH: Cortisol increases
Adrenal steroids
prolactin: Prolatin increases plactinoma ( sequential prolactin levels) = inhibitory effect on kisspeptin neurones, dowregulates downstream reproductive axis.
IGF (Stimulated by placement GH-variant)
Iodothyronines : Thyroid hormones, beta-hc shares common subunit with TSH
PTH related peptides: Calcium mobilisation
Which maternal hormones decrease during pregnancy?
Gonadotrophins Pituitary GH (Placental variant produced) TSH: Due to negative feedback of elevated levels of iodothyronines
What effect does oxytocin have?
Uterine contraction
Cervical dilation
Milk ejection
