Reproduction in birds

Question 1

What are the components of the avian male repro anatomy?

Answer 1

Paired testes
Epididymis and ductus deferens
No accessory male glands
+/- phallus

Question 2

Describe the anatomy of avian testis

Answer 2

Large compared to mammals
Increase in size when sexually active
L larger than R
Intrabdominal

Question 3

Describe the duct system of the male avian repro tract

Answer 3

small epididymis
highly coiled ductus deferens that terminates in urodeum of cloaca
Seminal glomus at end of ductus deferens (sperm storage)

Question 4

Where does sperm maturation happen in birds?

Answer 4

ductus deferens

Question 5

What changes in male avian repro anatomy when breeding

Answer 5

Testes increase in size 300-500 fold
Yellow-brown to white colour
Ductus deferens becomes more convoluted

Question 6

Why do some birds have a phallus, not a penis?

Answer 6

Erection is lymphatic, not vascular

Question 7

How do aves transfer semen?

Answer 7

cloaca-cloaca contact

Question 8

Describe the anatomy of the avian ovaries

Answer 8

L is functional (R functional if L removed
‘bunch of grapes’
Yellow (single cell with lipid inclusion)
Rapid follicular development

Question 9

What is different about avian ovarian histology?

Answer 9

no zona pellucida, membrana granulosa or cumulus oophorus

Question 10

Describe the endocrinology of follicle development and ovulation in birds

Answer 10

FSH => follicular growth
Follicles produce oestrogen (from theca and interstitial cells) and progesterone (from granulosa cells)
Oestrogen levels increasing => LH surge => oocyte release

Question 11

Describe the oestrogen-linked preparation for egg laying

Answer 11

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

Question 12

What is different between the triggers for ovulation between mammalian and avian species?

Answer 12

Mammalian - ovulation preceded by peak in LH and oestradiol, progesterone increases after ovulation
Avian - high progesterone is trigger for LH release causing ovulation

Question 13

Explain the changes in hormone production at ovulation in birds

Answer 13

Increased progesterone from granulosa cells
Decreased oestradiol from theca cells

Question 14

Why do birds not form a CL?

Answer 14

don’t sustain pregnancy so no need for CL

Question 15

What is the structure and function of the infundibulum in birds?

Answer 15

ciliated columnar epithelium
captures ovulated ovum

Question 16

What is ectopic ovum and what does it cause?

Answer 16

ovum doesn’t get caught by infundibulum
=> yolk free in coelomic cavity => inflammation (egg peritonitis)
Egg peritonitis causes:
- oviduct pathology
- stress
- obesity

Question 17

What is the function of sperm storage tubules in aves?

Answer 17

sperm can be stored for 10-14 days after mating at body temp
- allows one mating to fertilise a weeks worth of eggs

Question 18

Describe the process of egg production

Answer 18

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

Question 19

Label the avian female repro tract

Answer 19

Question 20

Label the avian male repro anatomy

Answer 20

Question 21

What is an egg clutch

Answer 21

Birds lay a limited number of eggs before incubation/brooding

Question 22

What is the open period in bird reproduction?

Answer 22

Window of time for LH release
~ 8-10 hrs long
onset of darkness -> 1 hr after light onset

Question 23

Describe the timing of ovulation and oviposition in birds

Answer 23

Question 24

Describe the endocrinology of brooding in birds

Answer 24

Repro tissues regress - LH, oestrogen, progesterone decrease
Prolactin increases:
- nesting activity and incubation
- gonadal regression
- parental care
- crop milk production

Question 25

What is crop milk?

Answer 25

semi-solid yellowy-white substance
high in protein and fat
Used to feed squabs in early days

Question 26

What is the brood patch?

Answer 26

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

Question 27

How does daylight impact avian reproduction?

Answer 27

Encephalic photoreceptors:
- fluorescent, incandescent light
- through eyes and skull
- must be in photosensitive state (primed by exposure to short day length for several weeks)

Question 28

How is sex determined in birds?

Answer 28

Ovum is either Z or W
sperm is always Z
ZW = female
ZZ = male

Question 29

What methods of sexing birds is there?

Answer 29

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