Reproductive System 1 - Reproductive systems and gametogenesis Flashcards
Reproductive system
Produces male and female gametes
Oocyte
sperm
Enhances fertilisation of an oocyte by a sperm
Female: nurtures new individual until birth
Produces reproductive hormones – controls above processes
Birth: Biological Sex
Female (vagina)
Male (penis)
Intersex (variation)
Anatomy doesn’t always dictate gender identity
Covering biological sex
Male Reproductive System - overview
Organs
Testes
Penis
Ducts
Epididymis
Ductus deferens
Urethra
Glands
Seminal vesicles
Prostate
Testes –anatomy
Testes covered in
Fibrous connective tissue
(under skin- scrotum)
Each testis contains
Connective tissue forms lobes
Seminiferous tubules (produce sperm)
Rete testis
Efferent ductules
Epididymis
Ductus deferens
Leydig cells (outside seminiferous tubule)
Produce testosteron
Gametogenesis
formation of the male and female gametes
Gametes (ovum and spermatozoa)
Oogonium/primary oocytes and spermatogonium
Females: oogenesis
Males: spermatogenesis
occurs in the gonads (ovary or testis)
Gametogenesis:
Meiosis
Termed
Meiosis
one cell undergoes two consecutive cell divisions
four daughter cells, each half as many chromosomes as the parent cell
Termed
meiosis I (reduction division, 23)
meiosis II
During fertilization, zygote receives _ set of chromosomes (23) from each parent
1
Seminiferous tubule
Where sperm formed
Mature in lumen, immature on outside
Leydig cells (testosterone)
Sertoli cells (nourish the germ cells and produce hormones)
Germ cells partially embedded
Spermatogenesis is the
Creation of sperm cells within the male gonads (testes)
What is the function of testes?
Exocrine – produce sperm
Endocrine – produce hormone
Spermatogenesis
Process of sperm maturation
Involves both mitosis & meiosis
Takes ~ 74 days to complete (incl maturation)
Spermatogenesis –seminiferous tubules
Germ cells
Immature at periphery
Mature near lumen
Mature (sperm cell or spermatozoa)
(semi mature)
The head, midpiece, and tail
transported through seminiferous tubules and ducts to the exterior of the body
Via rete testis to epididymis
Complete maturation
(although final stage just before fertilisation in oviduct)
Male Reproductive System - overview
Spermatozoa journey
Seminal vesicles in testis
Epididymis
Ductus deferens (vas deferens)
loops behind the urinary bladder
peristaltic waves to propel the sperm to approach the prostate gland
Seminal vesicles (semen)
Prostate (semen – surrounds urethra)
Urethra
Semen secretion
Nutrients (inc fructose)
pH regulators
Coagulation proteins (prolong time in vagina)
Proteolytic enzymes – release sperm – swim to oocyte
Female systems - medial section
Ovary
Uterine tube / fallopian tube/oviduct
Uterus
Vagina
Distendable smooth muscle tube, 10cm long
Small glands secrete lubricant
Related to rectum posteriorly and bladder/urethra anteriorly
female reproductive and urinary tracts open separately to the exterior
Female reproductive system overview
Ovary
Lies close to oviduct
Uterine tube / fallopian tube/oviduct
Uterus
Vagina
Cervix
Oocyte
Sperm cells deposited in vagina
Ampulla-site of fertilization
Uterine tissue layers
Endometrium – vascular and glandular
Stratum compactum - cuboidal ciliated epithelium*
Stratum spongiosum - loose connective tissue*
Stratum basale
*Slough during menstruation
Myometrium – 3 layers of smooth muscle
Perimetrium - peritoneum
Fallopian tubes
Also known as: Uterine tubes or Oviducts
Each 10cm long (approx.)
Three major components
Isthmus – narrowing
Ampulla – swelling – fertilization usually occurs here
Infundibulum – collecting area with fimbrae
Fimbrae that collect egg when released from ovary
Ovary composition:
Outer: connective tissue – ovarian follicles
Oocyte (female sex cell)
Centre: blood vessels nervous tissue
Developing follicles (cellular structures)
Surrounding developing oocytes
Ovary: follicular development
Primordial follicles (present at birth)
Puberty:
Primary follicles
Oocyte enlarges
Develops granulosa cells
Build up
Secondary follicle
Fluid filled vesicles
Thecal cells
Grafian follicle (mature)
Ruptures and secondary oocyte surrounded by cells released during ovulation
What are Follicles?
Primary follicle surrounded by granulosa cells
No. Layers of granulosa cells increases as maturation proceeds
Cells secrete oestrogen rich fluid into space surrounding oocyte called Antrum
Outer layer of granulosa cells condenses into layer of theca cells
Oogenesis
Occurs in the ovaries
Process of creation of an ovum (egg cell) from precursor cells
Begins prior to birth
primordial germ cells (oogonia) in foetal ovary
spans all of pre-reproductive & reproductive life
Similar process to spermatogenesis
Mitosis of primordial cells (oogonia)
(early) meiosis of primary oocytes
(late) meiosis of secondary oocyte
Oogenesis > development of oocytes
primitive germ cells (differentiation) > oogonia (mitosis_ > primary oocyte (early meiosis) > secondary oocyte (late meiosis) > Ovum
Stimulated and controlled by hormones secreted from granulosa and theca cells
Ovary: follicular and oocyte development
Follicle development 28 days
Hormonal control
Generally only one follicles forms a mature follicle
Remaining degenerate
Post ovulation
Forms corpus luteum
If pregnancy
Corpus luteum enlarges and persists
If no pregnancy
Corpus luteum lasts 10-12 days
degenerates
What is unique about final stage of oogenesis?
only occurs if fertilisation happens
