Microanatomy of reproductive system Flashcards
What are the ovaries?
Where female gametes are developed
What are the fallopian tubes?
Collects ovulated oocytes, site of fertilisation
What is the Uterus?
Site of decidualisation, menstruation, implantation and placental/foetal growth
What is the cervix?
‘neck’ of Uterus, provides a barrier to infection, dilates and secretes to regulate parturition and reproduction
What is the vagina?
External opening of female reproductive system, key to deposition of sperm and protection of the reproductive tract
Describe microanatomy of the ovaries?
- single layer germinal epithelium on exterior
- DIRCT Tunica Albuginea (capsule inside epithelial layer)
- Cortex - oocyte and follicular development
- Medulla - loose CT with blood vessels from hilum and lots of fibroblasts
By what process are oocytes lost in the ovaries?
Atresia
What are the different stages of follicular development?
1) primordial follicle
2) Primary follicle
3) secondary follicle
4) Early antral follicle
5) late antral follicle
What are the four main reproductive hormones in females?
- Follicle stimulating hormones
- Oestrogen
- Progesterone
- Luteinising hormone
What is the function of fibroblasts in the medulla of ovaries?
sensitive to hormone levels
What is found in the follicles of ovaries?
oocytes (Female gamete)
What phase of mitotic division do oocytes remain at until ovulation?
Prophase I of Meiosis I
What phase of mitotic division do eggs remain at until Fertilisation?
Meiosis I only completes Meiosis II at fertilisation
What do follicles become when they’re fertilised and so have no oocyte?
Corpus luteum - secrete lots of progesterone
What does the Corpus Luteum turn into if an egg is not fertilised?
Corpus Albican - follicle regresses, undergoes atrophy and becomes fibrotic
What is the function of the corpus luteum?
Main endocrine regulator before development of the placenta
Describe the structure of a primordial follicle?
single layer of small flattened follicular cells surround the oocyte and provide nutritional network and endocrine signalling
Describe how a primordial follicle forms a primary follicle?
- The primordial oocyte grows and secretes glycoprotein creating the zone pellucida
- Follicular cells develop into granulosa cells
Describe how a secondary follicle develops from a primary?
More granulose cells collect which start recruiting theca cells from the storma
What is the function of Theca cells?
- produce androgens
- form the corpus luteum post ovulation
Describe an Antral follicle?
- oocyte has layer around it zona pellucida
- which is surrounded by granulosa cells
- basement membrane
- layer of thecal cells
- Antrum (fluid filled cavity) within the granulose cells
What is the function of follicle stimulating hormone?
- Stimulate development go follicles from primordial to Graafian
- stimulates release of oestrogen from granulosa cells
What do follicular cells secrete?
1) Progesterone
2) precursor to oestrogen
How many layers of theca cells are there?
Theca interna
Theca externa
Describe the structure of a Graafian follicle (secondary antral follicle)?
- Antrum keeps expanding pushing the oocyte from the centre toward the edge of the cell
- layer of granulosa cells remain around the oocyte
- barrier of cells between oocyte and antrum called Corona radiata
Describe function of oestrogen in follicular/oocyte development?
- oestrogen secretion stimulated by FSH inhibits the FSH
- Some of the follicles start dyeing off as FSH only allows survival of one egg
- increase in oestrogen stimulates surge in LH
- LH causes ovulation
How does the oocyte leave the follicle?
- in response to LH surge collagenase activity increases
- increase in follicular fluid and pressure
- ovarian cortex surrounding follicle thins
- Follicle ruptures releasing the oocyte and corona radiata together
Describe the structure of the fallopian tube?
- Isthmus part of tube which connects to the uterus
- Infundibulum connects to the ovaries
- Ampulla is body of the tube in-between the other parts
- fimbriae are finger like extensions of the infundibulum
- wall of tube made of layer of simple columnar epithelium and layer of smooth muscle
Describe the mucosa and muscularis of the Fallopian tube?
- Simple columnar mucosa (secretory and ciliated)
- Infundibulum mucosa are highly folded and muscularis thin
- Ampulla mucosa highly folded and thick muscularis
- isthmus mucosa less folded and thickest musclularis
What is the function of the fimbriae?
During ovulation lie over the surface of ovary to create current to move oocyte into fallopian tube
Where does fertilisation take place?
Ampulla of fallopian tube
- spermatozoa deposited in vagina
- travels up cervix
- into uterus and up the Fallopian tube
What is secreted by the mucosa of Fallopian tube ?
- Tubular fluid which allows the oocyte to float
- fluid able to nourish the oocyte
What is the job of the ciliated cells?
- create current to move the oocyte down the tube toward the spermatozoa
- Spermatozoa has tail allowing it to swim up the Fallopian tube
What are the three layers of the uterus?
Endometrium (inner)
Myometrium
Perimetrium (outer)
Describe histology of the endometrium?
- Simple columnar epithelium
- functional zone (glands) also called Stratum functionalis, lost every month during menstruation
- basil zone called stratum Basalis
Describe the structure of the perimetrium?
Layer of connective tissue
Describe structure of the myometrium?
smooth muscle and lots of blood vessels
Why does the endometrium need to have lots of glands?
The zygote needs to implant on to a highly glandular tissue which will be able to support it
What is the male gametes and where are they developed?
Spermatozoa in the testes
What is the function of epidiymis?
Collects developing spermatozoa and site of maturation
What is the function of the ductal system?
Delivers sperm from testis in preparation for ejaculation
Function of the Accessory glands in male reproductive system?
produce seminal fluid to allow sperm movement and survival
What is the function of the penis?
hydraulic delivery system which transports spermatozoa to vaginal canal
What do LH and FSH stimulate in the male reproductive system?
LH - testosterone
FSH - Spermatozoa
Describe structure of the testes and its excretory ducts?
- Enclosed in thick connective tissue capsule called the tunica albuginea
- Tunica albuginea give rise to septa which divide organ into lobules
- Each lobule contains seminiferous tubules
- Tubules extend into rete testis before becoming efferent ducts that lead to epididymis
Describe structure of the epididymus?
- contains head, body and tail
- attaches to the testes
- connects to the vas deferens
What are the two specialised cells in the seminiferous tubules?
1) Leydig cells - in CT, secrete Testosterone
2) Sertoli cells - support and nourish developing germ cells
- Leydig surrond tubules and sertoli found within the tubules
What are the four levels of sperm development?
- Spermatogonia
- Spermatocytes (primary and secondary)
- Spermatids
- Spermatozoa
Where do sperms develop?
Seminiferous tubules of the testes
layers of sperm cells which are eventually released into lumen and travel to vas deferens
Histology of epididymus?
- pseudo stratified columnar epithelium
- epithelium have modified microvilli (called stereocilia)
- microvilli resorb some of testicular fluid
What is the function of epididymus?
- spermatozoa storage
- concentrates as removes fluid
Structure of the Vas deferens?
- encapsulated by dense irregular connective tissue (DIRCT)
- Columnar epithelium
- thick walled three layers of smooth muscle
- Inner and outer longitudinal and middle circular
- Contraction of muscle moves spermatozoa from epididymus to urethra for ejaculation
What are the accessory glands of the male reproductive system and what do they secrete?
1) Seminal vesicles - produce viscous secretion containing sperm-activating substances
2) Prostate gland - produce thin, milky fluid containing several enzymes (alkaline to counteract vaginal acidity)
3) Bulbourethral - Produce clear fluid prior to ejaculation to lubricate distal urethra and neutralise it
What are the sperm-activating substances?
Fructose, citrate and prostaglandins
What are the three vascular cylinders that make up the erectile tissue of the penis?
- Two Corpus Cavernosa (sit dorsal separated by median septum, surrounded by tunica albuginea)
- One corpus spongiosum (ventral and contains urethra)
