Kidney Anatomy and Structure

Kidney (Ren. s. nephros)

• Paired organ in the abdominal cavity and lumbar region, located retroperitoneally
• The right kidney is positioned more cranially than the left, except in swine
• The hepatorenal ligament connects the right kidney and the liver, except in swine
• Lateral and medial borders: Margo lateralis and Margo medialis
• Hilus renalis: the point on the medial border where the renal artery enters the kidney and the renal vein and ureter exit
• Ventral and dorsal surfaces: Facies ventralis and Facies dorsalis
• Cranial and caudal ends: Extremitas cranialis and Extremitas caudalis

Kidney Capsule Layers

• Capsula fibrosa: a fibrous capsule that closely covers the external cortical surface of the kidney, extending inward at the hilus to the renal sinus
• Capsula adiposa renis: an adipose capsule surrounding the kidney with perirenal fat, thicker dorsally than ventrally
• Fascia renalis: two layers that enclose the kidney and the capsula adiposa
• Peritoneum: covers the facies ventralis of the kidney

Kidney Internal Structures

• Lobus renalis: a renal lobe consisting of a renal pyramid and its cortical cap
• Pyramides renales: renal pyramids with the base at the cortex and the apex forming the renal papilla; number varies by species (su: 10-12, ov: 10-16, ca: 12-17, eq: 40-64)
• Columnae renalis: renal columns are sections of cortical tissue extending into the medulla around and between the pyramids
• Papilla renalis: the tip of the pyramid
• Calices renales: renal calices, the cup-like expansions of the renal pelvis
• Calices minores: minor renal calices that receive papillae
• Calices majores: major renal calices, the primary branches of the renal pelvis
• Pelvis renalis: the renal pelvis, a space within the renal sinus that collects urine and is the beginning of the ureter (except in swine)
• Sinus renalis: a cavity in the kidney at the hilus, containing fat and connective tissue surrounding the renal pelvis and vessels

Domestic Mammal Kidney Types

• Simple kidneys are based on the degree of fusion
• Smooth-unilobar (unipapillar): found in carnivores, equines, ovines and caprines, features a smooth external surface and a single internal papilla where the cortex and medulla are fused
• Smooth-multilobar (multipyramidal:) Kidneys have a smooth external surface, but numerous papillae internally

Kidney Details by Species

Dog

• Smooth unilobular kidneys
• The right kidney is ventral to T12-13 to L3
• The left kidney is ventral to L1-5
• Kidney shape: bean, dark brownish/bluish red
• Mass: 40-60g (large dogs)
• Have 12-17 renal pyramids to 1 papilla renalis
• Crista renalis goes to pelvis renalis

Cat

• Smooth unilobular kidneys
• The right kidney is located ventral to L1-4
• The left Kidney is located ventral to L2-5
• 38-44mm x 27-31mm x 20-25mm
• Mass: 7-15g
• A distinct venous network on the surface
• One papilla renalis to crista renalis to pelvis renalis

Small Ruminant

• Smooth unilobular kidneys
• The right kidney is ventral to T13 to L2
• The left kidney is ventral to L4-5
• Kidney Shape: Bean, light brown
• Short 5.5-7cm; thick, almost circular on cross section
• Mass of each: 100-160g
• Shallow hilus renalis
• Much perirenal fat
• Ovine kidneys are surrounded by thick masses of fat, which reduces mobility of the left kidney

Horse

• Smooth unilobular kidneys
• The left kidney is bean shaped and is ventral to T16-18 to L2-3
• Size: 15-20 cm x 11-15 cm
• Mass: 425-780 g
• The right kidney is heart shaped to VTh15-17 ↔ VL 1
• M= 480 840 g

Pig

• The pig has smooth-multilobar (multipyramidal) kidneys with 8-12 papillae (internally)
• Located in the abdominal cavity and lumbar region
• Kidneys lie ventrally to L1-4
• The right kidney does not touch the liver
• Bean shaped and dorsoventrally flattened
• Mass: 200-280 g

Cow

• Lobated-multilobar (multipyramidal) kidneys
• Contain a zona interna of cortex and zona externa of medulla
• Lobated surface externally divided into lobes (lobi renales), with numerous papillae internally
• Ren dexter: 18-24 cm long, located at T13 to L1-2
• Ren sinister: 19-25 cm long, located at L2 to L5, caudoventrally to the right
• The left kidney is related to the rumen on the left and the colon on the right
• Suspended from the roof of the abdominal cavity by renal vessels and enclosed in a fat-filled fold of peritoneum

Kidney Internal Structure

• Capsula fibrosa
• Cortex renis
• Basis pyramis
• Number of papilla renalis: 18-22
• Calix renalis
• Ramus ureteris cranialis and caudalis
• Ureter
• Sinus renalis
• Number of lobi renales: 12-25
• No pelvis renalis

Ureter

• The ureter is a paired duct with an abdominal part (pars abdominalis) running from the pelvis renalis through hilus renalis caudally
• The ureter has a pelvic part (pars pelvina) running from the pelvic cavity to the urinary bladder
• Tissue layers: tunica adventitia (fibrous outer coat), tunica muscularis (functional layer using peristalsis), and tunica mucosa with Gll. uretericae
• The ureter penetrates the dorsolateral wall of the urinary bladder obliquely
• The tunica adventitia is on [2]
• The tunica muscularis [3]
• The tunica mucosa [4]
• The ureter runs intra-murally for 2 cm before opening to the lumen by two slits via the ureteric ostium

Urinary Bladder (Vesica Urinaria)

• Has three defined regions: apex vesicae (blind cranial end), corpus vesicae (body between apex and neck), and cervix vesicae (funnel-shaped neck connecting to the urethra)
• Position is variable depending on fullness
• When filled, it extends into the peritoneal cavity (caudoventral abdomen), cranial to the pubis
• When empty, it is on the ventral floor of the pelvic cavity
• It is ventral to the uterus/rectum and descending colon
• Columna ureterica: a ureteral column is an elevation of mucosa produced by the ureter within the bladder wall
• Plica ureterica: a ureteral fold where two permanent folds extend from the urethral opening to the neck, uniting to form the urethral crest, which is continuous with the urethra
• Two folds bound a triangular area, which is absent in cattle
• Trigonum vesicae: a smooth area of mucous membrane between ureteral and urethral orifices on the dorsal internal wall of the bladder, exhibiting enhanced sensitivity
• Parts of the urinary bladder: apex vesicae, corpus vesicae, ureter, ostium ureteris, trigonum vesicae, crista urethralis, and urethra
• Three ligaments: Lig. vesicae laterale holds Lig. teres vesicae, Lig. teres vesicae (symmetrical, a vestige of a. umbilicalis), Lig. vesicae medianum which attaches it to the Linea alba

Urethra

• The final passageway for urine out of the bladder - a thin-walled tube from the cervix of the urinary bladder to the external urethral orifice
• The female urethra (urethra feminina) is an excretory passage for urine
• It varies in length among species: 6-8 cm in dogs, horses, and pigs, 10-13 cm in cows
• The internal urethral opening (ostium urethrae internum) is located at the base of the bladder, leading into the urethra
• The external urethral opening (ostium urethrae externum) is located in the vestibule of the vagina, where urine is expelled
• Ruminants and pigs have a suburethral diverticulum: a blind sac located ventral to the urethra, opening near the external urethral orifice, which can make urinary catheterization more challenging
• The male urethra (urethra masculina) serves as a passage for urine and reproductive fluids and has two parts
• The pelvic part (pars pelvina) lies within the pelvic cavity, closely associated with the prostate gland and reproductive structures
• The penile part (pars penina) extends through the penis to the external urethral opening
• The external urethral opening (ostium urethrae externum) is located at the apex of the glans penis, where urine and semen exit the body

Poultry Urinary System

• Ren Ureter →Cloaca-Urodeum
• There is no urinary bladder or urethra
• The kidney is paired, brown reddish, and prolonged, reaching the lung in fossa renalis/ventral synsacrum
• The kidneys consist of three renal divisions: cranial, middle, and caudal
• There is no pelvis renalis and no papilla renalis
• The ureter (paired) emerges from the ventral surface of the kidney in the middle renal division
• It enters the dorsolateral wall of the cloaca at an acute angle, opening into the urodeum at the ureteric ostium

Skin

• Skin is also known as cutis
• The common skin glands are glandulae cutis
• Subcutaneous tissue: Tela subcutanea is the loose connective tissue layer between the skin and the superficial fascia, interspersed with white fat
• Substantial fat accumulations (panniculus adiposus) are in the subcutis of the pig
• The subcutis of sheep, dogs, and cats has large amounts of loose connective tissue
• Horse, ox and goat subcutis is more tightly adherent to the trunk
• Local thickening of the subcutis allows the skin to form folds, including the dewlap (palear) in the ox
• Wattles (appendices colli) are the most common in goats and present in pigs and sheep on the ventral side of the neck with cartilage inside
• Merino sheep have transversal neck skin folds (plicae transversae colli)

Glands of the Skin

• Sebaceous glands are distributed over the integument with hair follicles
• They produce a fatty secretion (sebum) that mixes with the secretion of the apocrine sweat glands
• Specialized sebaceous glands: tarsal glands of the eyelids (Meibomian glands)
• Sebaceous glands of the lips and around the anus are specialized and are not associated with hairs
• In the pig, sebaceous glands are sparse and rudimentary
• Sweat glands are subdivided into eccrine and apocrine types based on the histology of their secretory process
• Apocrine sweat glands discharge albuminous sweat into hair follicles and provide the individual odor characteristic of each animal
• These glands are numerous in the horse, with additional openings on the skin surface around hair follicles with sweat frothing with work
• Eccrine sweat glands secrete watery sweat directly onto the skin and are not associated with hairs
• This type predominates in primates and can be only found in certain hairless or nearly hairless regions of the skin, such as the footpads of dogs

Specialized Skin Glands

• Skin glands in localized accumulations vary in size, form, and location among species
• Some may show specialized modifications and be associated with skin pouches
• In domestic mammals, the secretion of these glands functions as sexual or territorial markers
• All animals: ceruminous glands (gll. ceruminosae), which are sebaceous and modified tubular glands in the external acoustic meatus that secrete cerumen, a waxy substance
• Carnivores: paranalsinus glands (gll. sinus paranalis) and caudal glands (gll. caudae) are large sebaceous and tubular glands in an oval area on the dorsal surface of the tail
• Dogs: anal glands (gll. circumanales)
• Cats: circumoral glands (gll. circumorales)
• Carnivores and horses: skin glands of the footpads (gll. tori)
• Pigs: Rostral plane, carpal, and mental glands
• Sheep: nasal plane glands, infraorbital sinus glands, inguinal sinus glands, and interdigital sinus glands
• Goats: Horn gland
• Ox: Has nasolabial plane glands

Mammary Glands

• Mammary glands are gl. mammaria/mammae and consist of a species-specific number of mammary complexes that are arranged in a bilaterally symmetrical order
• In carnivores and pigs, mammary glands extend from the thoracic to the inguinal region
• In ruminants and horses, they are restricted to the groin and are called the udder (uber)
• Each complex consists of one or several mammary units, comprising a body (corpus mammae) and a teat (papilla mammae)
• Number varies by species: feline (8), canine (10), pig (14)
• Bovines udder has 4 vs sheeps and mares have 2
• Mammary glands of male mammals are unfunctional and rudimental
• Accessory mammary glands are usually unfunctional

Mammary Gland Structural Elements

• Stroma (deep udder fascia, interlobular separations) and parenchyma (alveolus)
• Smaller lobules (lobuli glandulae mammariae) make bigger mammary lobes glands (lobi glandulae mammariae)
• Various diameter milk ducts (ductus lactiferi)
• Lactiferous sinus (sinus lactifer) contains gland sinus (pars glandularis) and teat sinus (pars papillaris)
• Papillary duct and teat orifice which is surrounded by a smooth muscle sphincter
• Most species have one duct of papilla in the teat of bovine, sheep and goat, while others vary [mare 2, pigs 2, canines 5-10, felines1-7]

Foot Pads (Tori)

• Consist of epidermis tori and dermis tori alongside tela subcutanea tori with adipose tissue
• Developed only in dogs and cats
• Footpads contain eccrine sweat glands

Hair (Pili)

• Present over almost the entire body
• Anatomical parts: hair tip (apex poli), hair shaft (scapus pili), hair root (radix pili), bulb of hair (bulbus pili), hair follicle (folliculus pili), hair papilla (papilla pili), and arector muscles of the hair
• Three layers: cuticle, cortex and medulla
• Types of hair: Guard hairs (capilli) which form the shape and look of the body and covers the body
• Sheep hair without medulla inside is called wool or pili lanei
• Bristles also known as setae are common to all animals such as in the eyelashes and nostrils
• Transversely arrayed hairs create cross shaped patterns

Horse specific hair

• Cranial hairs between the ears - forelock (cirrus capitis).
• Mane (juba).
• Long hairs of the tail (cirrus caudae).
• The tuft of long hairs on the fetlock (cirrus metacarpeus/metatarseus).

Tactile Hairs (pili tactiles)

• Thick, their roots reach deeply into subcutis with a venous sinus whose walls have nerve endings to touch.
• Include supraorbital, infraorbital, zygomatic, buccal, upper and lower lip, mental and the carpal which is only in cats.

Horn Structure

• Three main parts: cornual process of the frontal bone (processus cornualis), dermis (dermis cornus), and epidermis (epidermis cornus)
• Three anatomical components: apex, body, and base

Hooves and Claws

• Equine hoof (ungula), hooves (paraungula) of ruminants and pigs, and claw (unguicula) in carnivores
• Equine hoof contains: distal phalanx, distal sesamoid bone, epidermis/hoof capsule, dermis and subcutaneous tissue.
• The dermis undergoes an analogous differentiation: perioplic, coronary, parietal, of the sole, and dermis of the frog
• The hoof capsule makes the epidermis and is from the hoof
• bovine hoofs have two principal and dewclaws, ruminants digits are only in 3rd and 4th position only, while dewclaws are rudimentary 2nd and 5th
• the anatomy of the pig hoof is similar to ruminants, but pig digit reduction is less advanced.
• dogs and cats do not have a frog on the hoof

Avian Integument

• Avian skin is very thin with poor blood supply
• Skin has One sebaceous gland (uropygial gland)

Feathers (pennae)

• Comb (turkeys), wattle, cornified beak, small foot scales, metatarsal, interdigital webs that covers skin are area call pteryla, areas without feathers are called apteria
• Consist of two parts:
• Shaft Calamus-free part Rachis-connection to vaxallium
• The contour or down feathers

Histology of the Urinary Tract and Glands

• Walls of the renal pelvis, ureter, urinary bladder, and urethra include a mucosa, muscularis of smooth muscle, and adventitia/serosa and might include a submucosa that mainly consist of transitional epithelium
• The ureter’s mucosa is folded, with transitional epithelium and lamina propia with no submucosa. Its tunica muscularis consists of 2-3 layers surrounded by serosa/adventitia.
• The urinary bladder is lined with transitional epithelial cells with flatten when urine is distended. Its tunica muscularis consist of 3 layers surrounded with serosa except where adventitia is located at the neck.
• The kidney is in a tough fibrous capsule that has no nephrons between. Has an granular cortex from ovoid filter units and has a striated medullar region
• Nephrons
• Epithelium in nephron Simple cuboidal for the most part
• The cortex has a corpuscles
• Renal medullar forms pyramids and its base faces the cortex while outer and inner medulla is full of tubules Interstitial Tissues
• Glomerular filtrate that passes through and secreted by tubule
• The skin consist of keratin that is continuously growing and desquamation
• The dermis supports its thickness derives from the mesoderm

Epidermis Layers:

• The basal is represented by the stem of the new mitosis. Has basale cells, melanin with melanocytes that has melanin and protects Keratin

• The stratum spinosum is at least several cells thick. Exhibit spinous cellular and grow surface

• The stratum granulosum is the most super facial thick Keratin

• The straum lucidum is at thick skin and keratin is most advance

The starum corneum has the most differentiated Langerians are antic presenting Markeles cells are mechanorecept Composed of two layers

• The reticlurar contains collagen and vascular system Is vascular system is a path for drags

Hair Anatomy

• Each follicle produces hairs that is divided into 4 regions.
• Infundibulum connects the oil
• The cell multiply and grow from division and proliferation

Gland Tissue

• Alveloli is parenchyma while the stoma is stoma
• The mammary tissue that has compount tubuloalveolar gland.
• Milk passes alvelois through interduct and duct
• The lumen secret the protein and lipid portion.
• Crotial nephron:
• Blood pressure
• Tubular action
• AD
• Hormone for body maintenance
• the balance in water is crucial for balance homeostasis that relays on urination

Bird systems

• Type the renal and Mammal
• Lactation Requires lactogenesis
• Progesterone to inhibit before birth and support estrogen through growth
• Cort to tricker to
• Orto causes the reject by the
• Glucogen hormone controls
• The FIL inhibits after no milk produces
• Collo contains protein
• Blood enters the pudic external art exits via the abdominal. This occurs and 20 precentage of the time. Lymp Crucioal