Reproduction in birds Flashcards
What are the components of the avian male repro anatomy?
Paired testes
Epididymis and ductus deferens
No accessory male glands
+/- phallus
Describe the anatomy of avian testis
Large compared to mammals
Increase in size when sexually active
L larger than R
Intrabdominal
Describe the duct system of the male avian repro tract
small epididymis
highly coiled ductus deferens that terminates in urodeum of cloaca
Seminal glomus at end of ductus deferens (sperm storage)
Where does sperm maturation happen in birds?
ductus deferens
What changes in male avian repro anatomy when breeding
Testes increase in size 300-500 fold
Yellow-brown to white colour
Ductus deferens becomes more convoluted
Why do some birds have a phallus, not a penis?
Erection is lymphatic, not vascular
How do aves transfer semen?
cloaca-cloaca contact
Describe the anatomy of the avian ovaries
L is functional (R functional if L removed
‘bunch of grapes’
Yellow (single cell with lipid inclusion)
Rapid follicular development
What is different about avian ovarian histology?
no zona pellucida, membrana granulosa or cumulus oophorus
Describe the endocrinology of follicle development and ovulation in birds
FSH => follicular growth
Follicles produce oestrogen (from theca and interstitial cells) and progesterone (from granulosa cells)
Oestrogen levels increasing => LH surge => oocyte release
Describe the oestrogen-linked preparation for egg laying
Synthesis of calcium ATPase from shall gland
Long bone medullary spaces calcified
Very low density lipoproteins (VLDL) produced from liver and transported to ovary (precursor of yolk)
Oviduct enlarges
What is different between the triggers for ovulation between mammalian and avian species?
Mammalian - ovulation preceded by peak in LH and oestradiol, progesterone increases after ovulation
Avian - high progesterone is trigger for LH release causing ovulation
Explain the changes in hormone production at ovulation in birds
Increased progesterone from granulosa cells
Decreased oestradiol from theca cells
Why do birds not form a CL?
don’t sustain pregnancy so no need for CL
What is the structure and function of the infundibulum in birds?
ciliated columnar epithelium
captures ovulated ovum
What is ectopic ovum and what does it cause?
ovum doesn’t get caught by infundibulum
=> yolk free in coelomic cavity => inflammation (egg peritonitis)
Egg peritonitis causes:
- oviduct pathology
- stress
- obesity
What is the function of sperm storage tubules in aves?
sperm can be stored for 10-14 days after mating at body temp
- allows one mating to fertilise a weeks worth of eggs
Describe the process of egg production
Infundibulum:
- secretes chalazae
- hold yolk in position during development
- ~1hr
Magnum:
- albumin laid down around oocyte
- ~3hrs
Isthmus:
- inner and outer shell membranes deposited
- ~1-1.5hrs
Shell gland (uterus):
- calcium carbonate added (shell)
- cuticle formed
- +/- pigment
- ~20 hrs
Vagina and cloaca:
- oviposition
- seconds to hours
Label the avian female repro tract
Label the avian male repro anatomy
What is an egg clutch
Birds lay a limited number of eggs before incubation/brooding
What is the open period in bird reproduction?
Window of time for LH release
~ 8-10 hrs long
onset of darkness -> 1 hr after light onset
Describe the timing of ovulation and oviposition in birds
Describe the endocrinology of brooding in birds
Repro tissues regress - LH, oestrogen, progesterone decrease
Prolactin increases:
- nesting activity and incubation
- gonadal regression
- parental care
- crop milk production
What is crop milk?
semi-solid yellowy-white substance
high in protein and fat
Used to feed squabs in early days
What is the brood patch?
De-feathered area around ventral pectoral muscles
oedematous, highly vascularised
Increased blood flow to heat eggs
Increased metabolism
Caused by ovarian hormones and tactile stimulation
How does daylight impact avian reproduction?
Encephalic photoreceptors:
- fluorescent, incandescent light
- through eyes and skull
- must be in photosensitive state (primed by exposure to short day length for several weeks)
How is sex determined in birds?
Ovum is either Z or W
sperm is always Z
ZW = female
ZZ = male
What methods of sexing birds is there?
Via DNA: blood from nail clipping, live cells from feather, eggshell
Surgical/endoscopic
Faecal steroids
Instrument sexing - protoscope used to observe gonads through intestinal wall
Vent sexing
Auto-sexing (only works if species have different M and F appearances
