term 3 Flashcards
pneuamtisided bone in birds
humerus
femur sternum pelvis and cervival and thoratic vertbrae
medulla of boe conbtains airsacks
reduces mass to allow for flight
types of bone
Compact/Cortical bone- Diaphyses of long bones Spongy/Cancellous- bone Epiphyses of long bones Vertebrae Skull Medullary bone- Calcium reservoir Forms c. 2 weeks before laying Formed from endosteum Hormonal control
Pneumatised bone
Bone marrow
medullary bone
found in birds Calcium reservoir Forms c. 2 weeks before laying Formed from endosteum Hormonal control present throught laying period skeletal weight increases medullary bone is reabsorbed polyostoic hyperostosis- found to varying degrees in many species when the female is ovulatory. The calcium storage in bone changes the pneumatic appearance to a solid mineral dense appearing medullary canal. The long bones of the legs are most often affected, and the long bones of the thoracic limbs are also involved in more pronounced cases. In females where the calcium/Vitamin D3 is insufficient, a moth-eaten appearance to these bones often occurs.
polyostoic hyperostosis-
found to varying degrees in many species when the female is ovulatory. The calcium storage in bone changes the pneumatic appearance to a solid mineral dense appearing medullary canal. The long bones of the legs are most often affected, and the long bones of the thoracic limbs are also involved in more pronounced cases. In females where the calcium/Vitamin D3 is insufficient, a moth-eaten appearance to these bones often occurs.
Cartilagenous skeletal template in birds
In adult
Hyaline cartilage at articular surfaces
Intervertebral discs
Menisci
decribe muscle in birds
Muscle bellies proximal
Less connective and adipose tissue cf mammals
Higher muscle fibre density
Basic muscle structure similar
Light (white) muscle-
Higher concentration of muscle fibrils
Less myoglobin & Cytochrome
Fast contraction, rapid fatigue (Fast twitch fibres)
Dark (red) muscle- Fewer myofibrils
More myoglobin
Slow contraction, slow fatigue (Slow twitch fibres)
Intermediate muscle
No diaphragm
Muscles of thoracic and abdominal wall
describe the avian skull and beak
Single occipital condyle Quadrate bone Pterygoid bone Large orbits Scleral ossicle Sole auditory ossicle- Columella, Extracolumella processes
beak- Wide species variability Maxilla- Pre maxillary and maxillary bones Mandible- Laterally flattened 5-6 pairs of fused bones Dental bone Splenial bone Angular bone Supra-angular bone Pre-articular bone Articular bone Mandibular symphysis
Chicken vertebral formula:
C14:T7:L+S 14:Cd4-9
thoratic vertebrae are fused
t7, lumbar, sacral, Cd1 vertebrae fuse to make the synsacrum
Caudal Vertebrae & Pygostyle
Spinal cord extends to last vertebral segments
describe the aviam trunk skeleton
Ribs Sternal & Asternal ribs 7-9 pairs Cartilagenous intercostal joint Uncinate processes Sternum Dorsally concave plate Carina/Keel Joints Atlantooccipital Atlantoaxial Flexible cervical spine T1, T6 Caudal vertebrae/pygostyle
avian Pectoral Girdle
Supports flight Coracoid Scapula Clavicles (fused to make Furcula) Foramen triosseum Muscles
avian thoratic limb
Humerus-Pneumatised Radius Ulna Carpometacarpals Digits Propatagium Pinioning
pectoralis responsible for downsroke supracoracoidus- upstroke ulna is wider and stronger bone central carplas fused alula-basterd wing
Anisodactyly
Most common toe arrangement Digits 2,3 & 4 Forward pointing Digit 1 (Hallux) Backward pointing Most common toe formation Suited to perching and grasping E.g. passerines, fowl and poultry, pigeons, raptors, gamebirds
Zygodactyly
Pairs of digits 1 & 4 Backward pointing 2 & 3 Forward pointing Useful for climbing and grasping E.g. Psittacines, woodpeckers, owls, cuckoos
Heterodactyly
Digits 3 & 4 forward pointing
Digits 1 & 2 backward pointing
Trogons only
Syndactyly
Similar to anisodactyly
Digits 2 & 3 joined
E.g. Kingfishers, Hornbills
Pamprodactyly
Digits 2 & 3 forward pointing
Digits 1 & 4 rotate forward & backwards
E.g. Swifts & Mousebirds
Didactyly
Only 2 forward pointing digits
Ostrich only
Palmate
Digits 2-4 united by webbing
E.g. waterfowl, gulls, flamingos, loons
Toe formation in birds can be…
Zygodactyly Anisodactyly Heterodactyly Syndactyly Pamprodactyly Didactyly
webbing formation in birds can be
Palmate
Totipalmate
Semipalmate
Lobate
Totipalmate
Webbing unites all 4 digits
E.g. gannets, boobies, pelicans, cormorants
Semipalmate
Small web between digits 2-4
E.g. Plovers, sandpipers, herons
Lobate
Lobes of webbing on digits 2-4
Some diving ducks have lobate D1
E.g. Grebes, Coots
Avian Adaptations for Flight
Skeletal adaptations Egg laying Eyesight Feathers Rigid Lungs, air Sacs and unidirectional air flow Seasonal reproductive organ enlargement No urinary bladder
Skeletal adaptations for locomotion – Flight
Carinate birds Pneumatised long bones- Internal struts for strength, Not all species Skeletal fusions Vertebral, carpus/manus, tarsus/pes Uncinate processes (ribs) Large sternum Coracoid bones
A & P Differences in diffrent birds accroding to flight
Long keel for propulsive take off- Pigeons, Parrots
Pectoralis: Supracoracoideus mass
Wing shapes
Adaptations for altitude/metabolic rates- Baffles Pulmonary oxygen extraction efficiency Cardiac output PCV
Flightless bird families
Ratites (Struthioniformes) Penguins (Spheniscidae) Kakapo Galapagos cormorants Some junglefowl Domestic ducks
Perching
Different foot formations
Automatic digital flexor mechanism
Digital tendon locking mechanism
Allows perching without spending energy
avian climbing
Arboreal species Woodpeckers/Tree creepers/Nuthatches Zygodactyl feet Tail assistance Direction Psittacines Zygodactyl feet Beak assistance
avain swimming
Propelled by pelvic limbs-
Flexion and extension of intertarsal joint
Alternate limb movement
Digital tendon locking mechanism
Underwater flight- Penguins
Porpoising- Diving in and out of water
Surface swimming- Decreases water resistance
Breathing
avian diving
Dabbling waterfowl
Surface divers
Plunge divers
Adaptations- Fewer or less pneumatised bones
Legs positioned caudally on pelvis
Internal nares
Adaptations in neck length and musculature
Subcutaneous air sacs
Poor waterproofing (Cormorants)
avain Integumentary homeostasis
Calcium- Vitamin D synthesis
UVB & Heat requirement
Thermoregulation- No sweat glands Feathers – insulation Feather colour Arteriovenous anastomoses Apteria
Water homeostasis- Nasal glands
avain Innervation and blood supply
Sparse innervation generally- Feather follicles
Beak
Blood supply- Subcutis & Dermis
Subepithelial capillaries
Dermal papillae
Arteriovenous anastomoses- Feet (Toes, pads, interdigital webbing)
Brood patch
Face
Avian Skin
Epidermis
Structure similar to mammals
Stratum corneum – horny layer covering exposed skin
surface
Stratum germinativum – living cells producing corneum
Membrana basalis – dermoepidermal junction
Dermis
Stratum superficiale – loose connective tissue with discrete dermal papillae associated with feather follicles
Lamina elastica - thin layer of elastic fibres
Subcutis
Mobile layer of tissue connecting skin to underlying structures
Feathers
Unique to birds Arise from epidermis β-keratins Specialised feather types Often brightly coloured Sexual dimorphism UV reflective patches
Flight Insulation Thermoregulation Waterproofing Camouflage Communication Protection Nest Lining
Follicle Shaft (Scapus) Rachis Calamus- quill Vane (Vexillum) Afterfeather (Hypopenna)
Micro Anatomy of a feather
Barbs -(Rami)
Barbules- (Radii/Barbulae)
Hooklets- (Hamuli/Barbicels)
Feather Types
Pennaceous/Vaned feathers- Contour Feathers- Coverts
Flight feathers
Tail feathers
Down Feathers-
Down feathers
Semiplumes
Powder Down
Feathers
Filoplumes
Bristles
Contour Feathers
Pterylae- Coverts (Tectrices)- Afterfeathers
Very variable
Flight feathers of the wings (Remiges)- Primary
Secondary
Tail Feathers (Rectrices)
Downy Feathers
lack hooklets
Natal down- seen in chicks
Down Feathers - Plumules, seen in adults for insulation
Powder Down - Pulviplumes, a cross between down and contour feathers and
Semiplumes
Filoplumes- assists in sensation
Bristles (feahters)
Rictal bristles
Sensory function
Eyes
Bill
avian moult
Species variability
Post breeding moult
Post juvenile moult
Shock moult- response to stress
Hormonal influence-thyroid horone
some become flightless
some taker turns to moult with mate
Featherless Regions
Thicker stratum corneum Specialisations Beak/Bill Cere Webbing Scales Pads Claws Spurs Cranial cutaneous structures
structure of beak
Keratinised epidermis
Rhamphotheca- the outer surface of the beak consists of a thin sheath of keratin called the rhamphotheca
Maxillary rhamphotheca
Rhinotheca
Mandibular rhamphotheca
Gnathotheca
Shapes Egg Tooth Lamellae Nail Bill tip organ Corpuscles of Herbst
avian Scales
Tarsometatarsus
Digits
Scuta (Dorsal)
Scutella (Plantar)
Apteria
one of the bare spaces between the feathered areas on the body of a bird.
Feather tracts
Pterylae
Featherless tracts Apteria Down feathers and semiplumes Contour feathers absent Surgical/Clinical landmark
Brood/Incubation patch
Females and males (spp. Differences)
Patagia
a membranous structure that assists an animal in gliding or flight
Cranial
Patagium cervicale
Propatagium
Patagium alulae
Caudal aspect
Metapatagium cervicale
Postpropatagium
avian Glands
No sweat glands
Epidermis is secretory
Sebaceous glands
Uropygial (Preen) Gland
Cloacal glands
Auricular glands
Salt glands
Marine species
Not sebaceous glands
Uropygial (Preen) Gland
Dorsal tail base (Cd4-pygostyle) Bilobed, symmetrical gland Excretory ducts Uropygial papilla Species variation Feathered vs unfeathered Presence/absence/papilla Preen oil Feather integrity Vitamin D Cosmetic effect
Overview of the Avian Digestive Tract
Very diverse feeding strategies Carnivores Omnivores Herbivores Specialised feeders Huge variation in gastrointestinal A & P Beaks Stomachs Intestinal length
avian Beak & Oropharynx
Beak/Bill- Rhamphotheca
Rhinotheca
Gnathotheca
Tomium
harder in granovores and carnivores and rubbery in water fowl
Choana- Oropharynx connected to nasal cavity
Tongue closes choana during inspiration
Choanal papillae- become blunt in absense of vit A
no soft pallet
Variable salivary glands
Tongue- Variable size, form and function
Lingual papillae
Sparse taste buds compared to mammals
Bitter taste
avain Oesophagus & Crop
Oesophagus - Dorsal to tracheal cervically Right side of neck Wide diameter Thin walled Longitudinal folds
Crop (Ingluvies)-Dilatation of the oesophagus
Proximal to pectoral cavity/thoracic inlet
Larger in granivorous/carnivorous species
Crop milk
Waterfowl/Owls– no true crop
Avian Coelom
No diaphragm Cranial coelom Caudal Coelom 2 x pleural cavities 4 x hepative peritoneal cavities Intestinal peritoneal cavity Pericardial cavity Air sac endoscopy Intraperitoneal injections
Proventriculus & Ventriculus (Stomachs)
Proventriculus – Glandular
Digestie Enzymes
True stomach
Ventriculus (Gizzard) – Muscular More developed in granivores Grit Masticatory Raptor pellets
raptors rely on chemicla digestion
Isthmus- Bridge
Aglandular
avian liver
Simple two lobed liver
Cardiohepatic silhouette
Gall bladder- Variable presence
Bile pigments
Biliverdin- green colour of urate
Hepatic Artery
Hepatic Vein
Hepatic portal vein
vit ADEK
carbohuydeate digestion
blod cell destruction
vit c production
avian Small Intestine
Relatively short- adaptation for flight
variatiom accroding to diet
Villi
Duodenum- Pancreas
Bile Ducts
Pancreatic Ducts
Jejunum
Ileum
Meckel’s diverticulum- differentiateds between jejunum and illium
avian Pancreas
Mesoduodenum- Between two duodenal limbs Pale yellow to pink Trilobed- Dorsal Ventral Splenic
Exocrine
Endocrine
AviannLarge Intestine
Caeca- Paired
Not in all speices
Rectum (prev. Colon)
Cloaca
Gut Associated Lymphoid Tissue (GALT)
avian
Diffuse lymphoid cells
Lymph Tonsils- Pharyngeal Tonsil Diffuse oesophageal lymphoid tissue Oesophageal tonsil Proventricular lymphoid tissue Pyloric Tonsil Peyers Patches Meckel’s diverticulum 2 x Caecal Tonsils Diffuse rectal lymphoid tissue Bursa of Fabricius Diffuse proctodeal lymphoid tissue
avian Cloaca
Common excretory passage-
Digestive
Urinary
Reproductive
Three sections
Coprodeum
Urodeum
Proctodeum
Coprourodeal fold
Uroproctodeal fold
Vent
Urine, urates, faeces all voided together from cloaca
Can be challenging to differentiate- Polyuria
Diarrhoea
Contamination of samples
Different dietary strategies
Granivorous birds
Short strong beak, often conical Large glandular crop Well developed ventriculus Longer intestines Distinct caeca
Different dietary strategies
Insectivorous birds
Finer, longer beak Rudimentary ventriculus Well developed proventriculus Short Intestine Rudimentary Caeca
Different dietary strategies
Carnivorous birds
Piscivorous birds
Carnivorous birds Strong, curved, often hooked beak Variable presence of crop Well developed proventriculus Rudimentary ventriculus Short intestine Well developed pancreas Rudimentary caeca
Piscivorous birds
As for carnivores but often longer beak
Different dietary strategies
Frugivorous birds
Rudimentary crop
Less well developed ventriculus
Short Intestine
Rudimentary Caeca
General Bird Handling considerations
Minimise handling time Gloves for wild birds Consider risk Warn owners of risk Mask clinical signs of disease Prior history & Distance Exam essential Preparation Key Equipment Recapture equipment Remove obstacles Positioning and ventilation Air sacs- best position is uprightso as to not compromise air sacs
May not be approprato get hands on at all
Observe whilst acclimatising Assess stability for physical examination Droppings Posture/Stance ODemeanour Respiratory rate/effort- not useful to take when handling bird Weigh in box if possible Behaviour Obvious abnormalities
Stress polyurea
Birds under stress produce wet dropping that can be mistaken for clinical signs
Avian Ventilation
air flows through the lungs in the same direction during both inspiration and expiration. In addition, both the intaking of air and the expelling of air are active processes, requiring muscle contraction.
During inspiration, the ribs are drawn forwards and the sternum lowered, the caudal air sacs receiving fresh air. Simultaneously, the Cranial air sacs receive air which was inhaled at the previous inhalation which is drawn from the lungs, this air has lost much of its oxygen content.
During expiration, the sternum is drawn caudal and dorsal, the air sacs are compressed, air from the caudal air sac passes through the lungs, while the air in the cranial air sac leaves via the trachea. Thus, oxygenated air passes through the lungs on both inspiration and expiration.
Avian Gas exchange takes place not in alveoli, as in mammals, but within air capillaries which are extensions of the parabronchial lumen. They are an interconnecting network of loops, and closely intertwine with blood capillaries. The air capillaries and blood capillaries are arranged so that flow is crosscurrent. This makes the gaseous exchange, which occurs from one to the other, extremely efficient.
describe female avian reproductive tract
Ovary
In the first 5 months after hatching, the ovary gradually develops from a small irregular structure with a finely granular surface into one where individual follicles can be observed.
Most birds have only left ovary but 2 ovaries are typical of many raptors.
Left Ovary lies caudal to the Adrenal Gland, close to the cranial tip of the Kidney.
Consists of:
Medulla: vascular with nerve fibres and smooth muscle
Cortex: peripheral
Suspended by the mesovarium.
Blood supply from the cranial renal artery
Artery is very short, making ovariectomy very difficult with risk of haemorrhage.
Contains from 500 to several thousand primary oocytes.
Follicles are pedunculated, suspended by a stalk containing smooth muscle that has a rich vascular and nerve supply.
Large, pendulous Follicles may contact the stomach, spleen and intestines.
Each consists of a large, yolk-filled oocyte surrounded by a highly vascular follicular wall.
Shortly before ovulation, a devascularized white band (stigma) appears opposite the stalk, indicating where the wall will rupture at ovulation.
The empty follicle (calix) regresses following ovulation and disappears in a few days.
No Corpus Luteum is required, since there is no embryo to maintain as there is in mammals.
oviduct:
The oviduct may be divided into the infundibulum, magnum, isthmus, uterus and vagina. The oviduct not only conducts the fertilized ovum to the Cloaca, but adds substantial amounts of nutrients. It also encloses the ovum within membranes and a shell, providing protection for the embryo. It conveys spermatozoa to the ovum for immediate fertilization and stores them for future use. One insemination is sufficient to fertilize the ova released during the following 10 days.
The right oviduct regresses in development under the influence of MIH.
In most birds only the left oviduct is present and functional. The right oviduct can be identified as a strand of tissue on the right side along the ventral side of the caudal vena cava
ccupies the left,dorsal part of the body cavity.
Related to the Kidney, intestines and gizzard.
Massive coiled structure approximately twice body length when fully functional..
Much reduced in juveniles and during the non-laying period.
Suspended from the roof of the body cavity by a peritoneal fold (mesoviductus).
Some coils are connected by a ventral continuation that forms the muscular ventral ligament.
Cilia are found along the entire length of the Oviduct. These facillitate sperm transport.
Egg transported by contractions of the Oviduct musculature.
Infundibulum
Consists of a fluted and tubular part.
Fluted part is thin-walled and stretched to form a slit (Infundibular Ostium).
Lateral end is attached to the body wall near the last rib.
Ostium is positioned by the left abdominal air sac in such a way that it can grasp the newly released oocyte.
Subsequent to ovulation, the ovum is engulfed by the Infundibulum.
Ovum resides here for 15-30 minutes.
Fertilization must take place in the funnel section of the Infundibulum before the oocyte gets surrounded by albumin.
Penetration by sperm usually occurs within 15 minutes of ovulation.
Infundibular glands provide the chalaziferous layer, the thin coating of dense albumin around the yolk.
Chalazae, the coiled strands that suspend the yolk and allow it to rotate so that the ferminal disc remains uppermost, develop further along the genital duct.
Some species have a sperm host gland in this area to store sperm for later fertilization.
Magnum
Longest part of the Oviduct.
Ovum resides here for ~2-3 hours.
Coiled with numerous tubular glands, giving it a thickened appearance.
Oestrogen stimulates epithelial stem cells to develop into three morphologically different cell types:
Tubular cell glands: Produce ovalbumin,lysozyme and conalbumin under the influence of Oestrogen. This gives the lumen a milky-white colour.
Ciliated cells
Goblet cells: synthesize avidin following exposure to Progesterone and Oestrogen.
Calcium, sodium and magnesium are added.
Isthmus
Demarcated from the Magnum by a narrow aglandular zone.
Folds less prominent than the Magnum, but the glands secrete more albumin.
Divides the Magnum from the Uterus.
Present in poultry but not in Psittacines.
Ovum resides here for ~1-2 hours
Inner and outer shell membrane formation.
Uterus
Holds the egg during shell formation.
80% of time is spent here.
Very vascular to aid calcium deposition.
Calcification first occurs slowly, increases, then decreases again ~2 hours prior to oviposition.
Shell pigments (primarily protoporphyrin and biliverdin) are deposited via ciliated cells over 3 hours until 30 minutes before oviposition.
Vagina
Muscular S-shaped tube through which the completed egg passes when it is expelled.
Vagina is separated from the Uterus by a vaginal sphincter which terminates at the Cloaca.
Ends at a slitlike opening in the lateral wall of the Urodeum.
Smooth muscle more powerful than the rest of the oviduct.
Numerous mucosal folds lined by ciliated and non-ciliated cells.
Few tubular mucosal glands with secretory function.
No role in egg formation.
In some species, egg can remain here for hardening before passing out of the oviduct to the Urodeum.
Sperm Host Glands
Sperm host glands are at the uterovaginal junction of domestic fowl.
Sperm can be stored here and remain viable for 7-14 days in the Chicken or over 21 days in the Turkey.
No innervation or contractile tissue.
Well-developed vascular system.
Raptor A & P Considerations
Large crop except owls- Rehydration pre feeding Owls good night vision Casting indigestible material- Variable Owls feathered legs Talons Beaks (Tomial tooth) Nares- Operculum (Don’t confuse with rhinolith) cartelagenous flap that sits in nare Baffles- protects from wind speeds
Poultry Clinical Exam
Stance Pin bones Wattle & Comb colour Sinuses Ear lobe colour Feathers- Parasites, NB Red mite lie off host Vent Legs/scales Pododermatitis
Waterfowl A & P Considerations
No apteria- featherless tract for blood sampling No true crop Webbed feet Feathered preen gland Drake curl in male duck Feather/Moult abnormalities Do they fly?
Pigeon A & P Considerations
Cervical plexus Blue cervical skin Powder down Flash moult under stress Crop- Crop milk Vestigial uropygial gland
Microchipping birds
Standard microchips
Subcutaneous implantation
Intramuscular in large/thin skinned species
Tissue Glue
BVZS
Left pectoral standard
Otriches - Pipping muscle inback of head
Penguins - Subcutaneously at base of neck
WSAVA
Psittacines & Falconiformes – Left Pectoral
Old & New World Vultures – Base of Neck
Large (>1.5kg or long legged) – Dorsally at juncture of neck & body
Small – Medium (<1.4kg) Left pectoral
BTO Rings
Wild Birds Passive monitoring British Trust for Ornithology (BTO) rings Open rings Unique code Data stored at NH Museum London Longevity Survival Migration patterns Population changes NB differentiate between open/split- wild and closed rings- captive birds
Tattoos/Ink stamps Racing Pigeon Rings GB – Royal Pigeon Racing Association NPA – National Pigeon Association NEHU- North of England Homing Union NWHU – North West Homing Union SU – Scottish Union IHU – Irish Homing Union WHU – Welsh Homing Union
Uncinate processes of ribs
The uncinate processes of the ribs are extensions of bone that project caudally from the vertical segment of each rib. (Uncinate means hooked from Latin uncinatus, from uncinus, barb, from uncus, hook.) They are found in birds (except for screamers)
These processes can serve to attach scapula muscles,[1] and help to strengthen the rib cage overlapping with the rib behind them.[1][2] They are also shown to have a role in respiration by increasing the effectiveness of muscles involved in inspiration including the appendicocostal muscles.[3] The processes are short in walking birds and long in diving species and are of intermediate length in non-specialist birds
gizzard
lso referred to as the muscular stomach or ventriculus. It is connected by the isthmus to the proventriculus and to the duodenum.
The gizzard allows mechanical reduction of tougher material through powerful muscular development
The gizzard consists of two thick masses of muscle that insert on tendonous surfaces. In seed eating birds, grit is digested to increase the grinding down of food particles. Its surface is covered by a glistening tendonous layer. The cranial and caudal extremities are formed by a powerful red muscular tissue. A circular aponeurosis is present, connecting the cranial end of the gizzard to the isthmus and the caudal end to the duodenum. It appears yellow due to bile reflux from the duodenum. When the thin muscles of the gizzard contract, food passes from the gizzard into the duodenum, when the thick muscles of the gizzard contract, food moves back into the proventriculus.
The gizzard has a thin, but tough mucous membrane. It has a pale, thin lining raised into ridges with three layers of lamina muscularis. The gizzard also has cuboidal epithelium and some tubular glands present. There is a thick keratin layer to protect the muscle.
The cuticle of koilin is a carbohydrate complex, present due to the solidifying of the glandular secretion. It is replenished as it is worn down.
There is no gizzard in falconiformes (raptors etc.) or in stringiformes (owls etc.). There is also no gizzard in gulls.
Avian Ventilation
air flows through the lungs in the same direction during both inspiration and expiration. In addition, both the intaking of air and the expelling of air are active processes, requiring muscle contraction.
During inspiration, the ribs are drawn forwards and the sternum lowered, the caudal air sacs receiving fresh air. Simultaneously, the Cranial air sacs receive air which was inhaled at the previous inhalation which is drawn from the lungs, this air has lost much of its oxygen content.
During expiration, the sternum is drawn caudal and dorsal, the air sacs are compressed, air from the caudal air sac passes through the lungs, while the air in the cranial air sac leaves via the trachea. Thus, oxygenated air passes through the lungs on both inspiration and expiration.
Avian Gas exchange takes place not in alveoli, as in mammals, but within air capillaries which are extensions of the parabronchial lumen. They are an interconnecting network of loops, and closely intertwine with blood capillaries. The air capillaries and blood capillaries are arranged so that flow is crosscurrent. This makes the gaseous exchange, which occurs from one to the other, extremely efficient.
describe female avian reproductive tract
Ovary
In the first 5 months after hatching, the ovary gradually develops from a small irregular structure with a finely granular surface into one where individual follicles can be observed.
Most birds have only left ovary but 2 ovaries are typical of many raptors.
Left Ovary lies caudal to the Adrenal Gland, close to the cranial tip of the Kidney.
Consists of:
Medulla: vascular with nerve fibres and smooth muscle
Cortex: peripheral
Suspended by the mesovarium.
Blood supply from the cranial renal artery
Artery is very short, making ovariectomy very difficult with risk of haemorrhage.
Contains from 500 to several thousand primary oocytes.
Follicles are pedunculated, suspended by a stalk containing smooth muscle that has a rich vascular and nerve supply.
Large, pendulous Follicles may contact the stomach, spleen and intestines.
Each consists of a large, yolk-filled oocyte surrounded by a highly vascular follicular wall.
Shortly before ovulation, a devascularized white band (stigma) appears opposite the stalk, indicating where the wall will rupture at ovulation.
The empty follicle (calix) regresses following ovulation and disappears in a few days.
No Corpus Luteum is required, since there is no embryo to maintain as there is in mammals.
oviduct:
The oviduct may be divided into the infundibulum, magnum, isthmus, uterus and vagina. The oviduct not only conducts the fertilized ovum to the Cloaca, but adds substantial amounts of nutrients. It also encloses the ovum within membranes and a shell, providing protection for the embryo. It conveys spermatozoa to the ovum for immediate fertilization and stores them for future use. One insemination is sufficient to fertilize the ova released during the following 10 days.
The right oviduct regresses in development under the influence of MIH.
In most birds only the left oviduct is present and functional. The right oviduct can be identified as a strand of tissue on the right side along the ventral side of the caudal vena cava
ccupies the left,dorsal part of the body cavity.
Related to the Kidney, intestines and gizzard.
Massive coiled structure approximately twice body length when fully functional..
Much reduced in juveniles and during the non-laying period.
Suspended from the roof of the body cavity by a peritoneal fold (mesoviductus).
Some coils are connected by a ventral continuation that forms the muscular ventral ligament.
Cilia are found along the entire length of the Oviduct. These facillitate sperm transport.
Egg transported by contractions of the Oviduct musculature.
Infundibulum
Consists of a fluted and tubular part.
Fluted part is thin-walled and stretched to form a slit (Infundibular Ostium).
Lateral end is attached to the body wall near the last rib.
Ostium is positioned by the left abdominal air sac in such a way that it can grasp the newly released oocyte.
Subsequent to ovulation, the ovum is engulfed by the Infundibulum.
Ovum resides here for 15-30 minutes.
Fertilization must take place in the funnel section of the Infundibulum before the oocyte gets surrounded by albumin.
Penetration by sperm usually occurs within 15 minutes of ovulation.
Infundibular glands provide the chalaziferous layer, the thin coating of dense albumin around the yolk.
Chalazae, the coiled strands that suspend the yolk and allow it to rotate so that the ferminal disc remains uppermost, develop further along the genital duct.
Some species have a sperm host gland in this area to store sperm for later fertilization.
Magnum
Longest part of the Oviduct.
Ovum resides here for ~2-3 hours.
Coiled with numerous tubular glands, giving it a thickened appearance.
Oestrogen stimulates epithelial stem cells to develop into three morphologically different cell types:
Tubular cell glands: Produce ovalbumin,lysozyme and conalbumin under the influence of Oestrogen. This gives the lumen a milky-white colour.
Ciliated cells
Goblet cells: synthesize avidin following exposure to Progesterone and Oestrogen.
Calcium, sodium and magnesium are added.
Isthmus
Demarcated from the Magnum by a narrow aglandular zone.
Folds less prominent than the Magnum, but the glands secrete more albumin.
Divides the Magnum from the Uterus.
Present in poultry but not in Psittacines.
Ovum resides here for ~1-2 hours
Inner and outer shell membrane formation.
Uterus
Holds the egg during shell formation.
80% of time is spent here.
Very vascular to aid calcium deposition.
Calcification first occurs slowly, increases, then decreases again ~2 hours prior to oviposition.
Shell pigments (primarily protoporphyrin and biliverdin) are deposited via ciliated cells over 3 hours until 30 minutes before oviposition.
Vagina
Muscular S-shaped tube through which the completed egg passes when it is expelled.
Vagina is separated from the Uterus by a vaginal sphincter which terminates at the Cloaca.
Ends at a slitlike opening in the lateral wall of the Urodeum.
Smooth muscle more powerful than the rest of the oviduct.
Numerous mucosal folds lined by ciliated and non-ciliated cells.
Few tubular mucosal glands with secretory function.
No role in egg formation.
In some species, egg can remain here for hardening before passing out of the oviduct to the Urodeum.
Sperm Host Glands
Sperm host glands are at the uterovaginal junction of domestic fowl.
Sperm can be stored here and remain viable for 7-14 days in the Chicken or over 21 days in the Turkey.
No innervation or contractile tissue.
Well-developed vascular system.
what methods can be used to determine the sex of a bird
DNA:
Bird Sexing by DNA, using samples of feathers, blood or eggshells is currently the most advantageous method, representing the following prominent benefits:
No surgical intervention such as anaesthetics required
Applicable to birds of any age, any time of the year
The birds are not subjected to the stress of transport
Reliable method applicable to most species
Sexual dimorphism:
mosrt apparent during spring and summer so sometimes season dependent
sometimes difficult
can tbe used for chicks
Size: hard without comparison or experience
behaviour: singing, fighting, migration
chromosome inspection
surgery: invasive
avain cardiovascular system
Heart is proportionately large relative to body size compared to mammals to meet the metabolic demands of flight
Cardiac output is higher attributed to a higher heart rate (up to 1000bpm!). very efficient. linked to sixe
Nucleated red blood cells- in mammels theyre anuclear
Additional renal portal system- same as reptiles
right atrioventricular valce has two cusps as in dogs and cats and heart strings
left atrio ventricular valve has one cusp and no heart srtings
aorta goeas to brachisophalic trunk then splits into two breachisophalic arteries, then to the cephalic and subclacvian
also becomes intercostal arteries then crainial and cadal mesenteric, then to kidneys and hindlimbs
3 vena cave return vlood to hear- 1 caudal 2 cranial
only 1 pulmanary vein
renal portal system
system of shunts that move blood from hindlimbs to kidneys
regulation of body fluid- esspecially usefull for dehydration
when injecting into hind lombd srug will go throughn renal system- toxisity, breakdown of drug
blood sampling in birds
Wing vein /cutaneous ulna vein
Medial tarsal/ medial tarsal metatarsal
Jugular vein (right bigger then left) species specific
Occipital venous sinus (under anaesthetic only)
Wing vein /cutaneous ulna vein
injection
blood sampling
just beyond point of elbow
Occipital venous sinus
done only under anethesia
head must be flexed to open up sinus caudal to the occiput
back of head
describe the upper respiratory tract of birds
nostral links to nasal cavity
nasal septum divides nasal cavity
concha- bone structures that increase surface area in nasal cavity, traps dust
the caudal choncha is most rostral followed by the middle and rotral choncha
all connect to the infraorbital sinus by narrow space
sinus not engulfed in bone. just sit under skin ans so sinusitis can cause swelling of the head
trachea and syrinx of bird
No vocal folds, syrinx is responsible for vocalisations further down. absence of vocal folds
Trachea held open by complete cartilage rings, palpable on right hand side
Syrinx is found at junction between trachea and primary bronchi. Membranes of primary bronchi resonate to create a vocalisation. area of no cartilage rings
The male duck and swan have an osseus bulla on the left of the syrinx believed to be a resonator
Song birds have more muscles attached to syrinx to allow for more variation of noised
e.g. sternotrachialis foes form sternum to trachae
describe the lungs in birds
relativly small
not expansile due to ridgid thorax
no lobes
no pleural cavity- thorax and abdomen in single cavity
Parabronchii for efficient gas exchange- much more efficint gas exchange, bird equvilent of alvioli
doubly efficent as parabonchi are tubes and not dead ends
oxygenated air travels through on both inspiration and expiration
lungs sit against dorsal body wall
describe airflow beteen the parabronchi and airsacks
Chicken parabronchi (tertiary bronchi) are organized in parallel connection, and the air flows in one way during inspiration and expiration due to the air sacs. Thus, birds have a more efficient gas exchange than human, whose airways end blindly and air moves in and out during ventilation , leaving a physiological dead space.
air moves form trachea to parabornchi to air sacs throught body
then passes through parabronchi into other airsac and then out again
airsacs act like bellows that draw in air
gas exhange takes place in the parabronchi- countercorent exhange as blood flows oposite way to air
desciebe the avian respiritory cycle
- On first inhalation, air flows through the trachea & bronchi, primarily into the posterior (rear) air sacs
- On exhalation, air moves from the posterior air sacs into the lungs
- With the second inhalation, air moves from the lungs in to the anterior (front) air sacs
- With the second exhalation, air moves from the anterior air sacs back into the trachea and then out
Air sacs
Respiration but not gas exchange
Move air through the lungs on inspiration and expiration
Makes body lighter
airsacs extend into pneumatised bones
cervical air sack, interclavicular air sack, humeral,
anterior airsack, posterior thoratic (paired) airsac, abdominal airsac (paired)
also grouped into cranial (exten form crainial aspect to humerus which is pneumitised) and caudal airsacs (etends into pelvis)
if pneumatised bone is broken, infection can spread to lungs
Pneumatic bones
The pneumatic bones are important to the chicken for respiration. They are hollow bones which are connected to the chicken’s respiratory system and are important for the chicken to breathe.
Examples of pneumatic bones are the skull, humerus, clavicle, keel (sternum), pelvic girdle, and the lumbar and sacral vertebrae.
rle in thermoregulation
cranial air sac
cervical airsac
intercavicular airsac
anterior thoratic air sacs, humeral air sac
caudal airsac
posterior thoratic airsacs
abdominal airsacs
countercurrent exchange in birds
blood flows oposite direction to air in parabronchi as gas exchnge takes place
oxyge content in air depleats as it moves through parabronchi, oxygen content in blood parrallel to parabronchii increases in oposite direction
creats gradient that drives oxygen to move into blood
efficient air exchange for high metabolic demant and allows birds to deal with low levels of oxygen at high altitude
very good thermoregulation via blood stream and out through repiritory system due to this
avain endocrine system
Pituitary
Anterior- TRH ACTH Adrenocorticotrophic hormone Sex hormones LH, FSH Melanin stimulating hormone Growth hormone Prolactin
Posterior-
Anti-diuretic hormone
Oxytocin
Adrenals- Corticosterone Aldosterone Norepinephrine Epinephrine
Thyroid-
Thyroid hormone
Parathyroid-
Parathyroid hormone
Ultimobrachial bodies-(anatomically distinct from the thyroid)
Calcitonin
Pineal body-
Melatonin
Pancreatic Islets of Langerhans-
Insulin
Glucagon
Gonads-
Androgens
Oestrohens
avain female reproducitve anatomy
One ovary and oviduct
Regression on the R oviduct occurs from day 10 of incubation
left oviduct develops rapidly at about 16 weeks
birds come into lay with increae in photoperiod
birds that have two ovaries e.g sparrow hawk, long eared owl, buzzard
there are pin bones around cloaka that increase in distance from eachother when bird is in lau “about three finger width”
ovary not attached to oviduct so infandibulum mut cathc egg. can lead to yolk in peritoneal cavity and egg peritonitus
pathology involved in the hens reproductive cycle
Ovarian pathology - Internal ovulation - Egg peritonitis - Neoplasia Oviduct pathology - Salpingitis - Proplase - Egg binding/dystocia - Neoplasia Bone pathology - Osteoporosis - Keel bone fractures Mating injuries
What to look out for in the clinical exam of a hen
Hunched Penguin-like stance Abdominal distention Gently palpate abdomen Laying deformed or soft shelled eggs Reduced activity levels Reduced feed and water consumption Frequent eye closing Check body condition Find out about diet, housing and ventilation
describe the path of the egg in the female chicken
from the ovary it is caught by the infandibulum where it spends 15 mins nd is fertalised, then goes through the magnum and stays for around 3 hours and gains albumen and isthmus where it spends around 1.25 and gains a soft shell hours to the shell gland where it spends 21 hours getting a hard shell and is then expelled via the vagina and cloaca
yolk protein is formed in..
the liver and is transpirted to ovary via blood supply
post ovulatory follical
contains granuloma and foecal cells
