A part of an organ that constitutes a distinct modular sub-unit. In some cases, the organ may also contain other sub-units of identical or similar types, in other cases this may be a distinct entity.
osseus labyrinth vestibule +
osteon +
otic and occipital +
otic plate of pterygoid
outer medulla of kidney +
outer medulla vasa recta ascending limb
outer medulla vasa recta descending limb
pancreatic lobule +
papilla of tongue +
papillary muscle of heart +
parafoveal part of retina
parasagittal crest
parenchyma +
pars articularis of mandibular arch
pars canalicularis of petrosal
pars convoluta of oviduct
pars cylindriformis ilei
pars externa plectri +
pars facialis of maxilla +
pars facialis of maxillopalatine
pars flaccida of tympanic membrane
pars glenoidalis of quadratojugal
pars inferior of labyrinth
pars intermedia of adenohypophysis
pars interna plectri
pars jugalis
pars media plectri +
pars plana of ciliary body
pars plicata of ciliary body
pars recta
pars reflexa of masseter
pars reuniens
pars suprascapularis
pars tensa of tympanic membrane
pars tuberalis of adenohypophysis
pectinate muscle
pectineal ligament
pedicel
perifoveal part of retina
periventricular zone of hypothalamus +
planum terminale
planum triangulare
pleurapophysis
pontine tegmentum +
posterior fascicle of palatopharyngeus
posterior part of tongue +
posterior ramus of cleithrum
posterolingual region
presacral shield
presubiculum +
processus confluens
proctodeum portion of cloaca
prostatic utricle
pterygopharyngeal part of superior pharyngeal constrictor