2. reproduction in birds

Question 1

what are the components of the avian male reproductive tract

Answer 1

• paired testes
• duct system (epididymis and ductus deferens
• +/- phallus

Question 2

discuss the testis of birds

Answer 2

• large in comparison to mammals
• increase in size when sexually active
• left larger than right
• intraabdominal
• cranioventral to first kidney love, near abdominal air sac
• spermatogenesis therefore better at cooler temperatures (mornings)

Question 3

discuss the duct system in avian males

Answer 3

• small epididymis
• highly coiled ductus deferens which terminates in urodeum on papilla (site of sperm maturation)

Question 4

discuss how testes in breeding vs non-breeding avian males change

Answer 4

• can increase in size 300-500 fold
• colour changes from yellow-brown to white
• ductus deferens more convoluted
• seminal glomus = sperm strage

Question 5

discuss the phallus in birds

Answer 5

• varies by spp
• erection lymphatic, not vascular
• semen transfer by cloaca to cloaca contact

Question 6

discuss the ovaries in the avian female reproductive system

Answer 6

• left ovary is functional
• right not (vestigial) unless left removed
• looks like a bunch of grapes
• yellow: single cell with huge lipid inclusion
• rapid follicular development
• hierarchy of maturation
• usually 10 yolky follicles, large number of small yellow follicles
• numerous smaller white follicles

Question 7

avian oocytes have zona pellucida true or false

Answer 7

false

Question 8

discuss the endocrinology of the hen

Answer 8

• FSH responsible for follicular growth
• follicles produce: oestrogen from theca cells and interstitial cells
• progesterone from granulosa cells
• opposite of mammal
• increasing oestrogen triggers LH surge and oocyte release

Question 9

the increase in oestrogen causes what events to occur in preparation for egg laying

Answer 9

• synthesis of calcium ATPase (in shell gland)
• long bone medullary spaces calcified
• very low density lipoproteins produced and transported to ovary (precursor of yolk)
• oviduct enlarges
• plumage, comb size and sexual receptivity change

Question 10

which hormones are high prior to ovulation in the bird

Answer 10

• progesterone
• LH
• high progesterone is trigger for LH release and therefore ovulation

Question 11

do birds have a corpus luteum

Answer 11

no - dont need one as dont maintain pregnancy to give birth to live young (development occurs in the egg outside the body)

Question 12

what is egg peritonitis

Answer 12

• ovum misses the infundibulum
• yolk free in coelomic cavity
• caused by oviduct pathology, stress and obesity

Question 13

outline the pathway of an egg through the hen and how long it takes to produce an egg

Answer 13

1. infundibulum: <1hr
2. magnum : >3 hrs
3. isthmus: 1-1 1/2 hrs
4. uterus/shell gland: 20 hrs
5. vagina and cloaca: seconds to hours

Question 14

the infundibulum in the bird does what

Answer 14

• secretes chalazae (whitish string like structures)
• holds yolk in position during development

Question 15

what happens to the egg in the magnum

Answer 15

albumin laid down around the oocyte

Question 16

what happens to the egg in the isthmus

Answer 16

inner and outer shell membranes deposited

Question 17

what happens to the egg in the shell gland

Answer 17

• calcium carbonate added
• cuticle developed
• +/- pigment

Question 18

discuss sex determination in birds

Answer 18

females: heterogametic: ZW
male: homogametic: ZZ
therefore female determines sex of egg
how to sex:
- blood
- live cells from plucked feather
- eggshell
- endoscopy
- faecal steroids
- instrument sexing
- vent sexing (hard)
- auto-sexing (colour and feather if male and female have distinct sex differences)