What are the three main parts of the pituitary gland?
Anterior and posterior parts and infundibulum is the easiest classification. Alternatively pars distalis, pars tuberalis, pars intermedia, neurohypophysis, and infundibulum... (see pituitary gland article).
Embryologically how is the gland formed?
The gland has dual origin: 1) ectoderm of the primitive mouth cavity and 2) neuroectoderm of the diencephalon. Rathke’s pouch forms as an ectodermal outpouching of stomodeum (primitive oral cavity lined by ectoderm) and the infundibulum which forms in the floor of diencephalon (part of the neural tube). The infundibulum grows ventrally towards the stomodeum while imultaneously Rathke’s pouch grows dorsally. Rathke’s pouch eventually loses its connection with the stomodeum and forms a discrete sac which adheres to the infundibular process. This sac differentiates to form the adenohypophysis of the pituitary: pars distalis, pars tuberalis, and pars intermedia. The distal part of the infundibulum differentiates to form the posterior pituitary (neurohypophysis) and retains the connection with the hypothalamus as the stalk.
Briefly describe the blood supply of the pituitary gland. How do the anterior and posterior pituitary differ in this respect?
The anterior pituitary is supplied a portal circulation; arterial supply to the superior most infundibulum drains into the hypophyseal portal venous plexus which descends along the infundibulum, before branching once more into a capillary network which supplies the anterior pituitary. The posterior pituitary receives more conventional arterial supply.
On midline sagittal images, identify as many structures as you can.
If you are stuck for things to look for, try the following: anterior and posterior pituitary, infundibulum, optic chiasm, mammillary bodies, sphenoid sinus, clivus, and supraoptic and infundibular recesses of the third ventricle.
Multiplanar, multisequence imaging has been obtained through the brain including post contrast dynamic images through the pituitary fossa.
The pituitary is normal in size, signal, and dynamic contrast enhancement. Apparent hypodensity seen on the left side of the gland on sagittal imaging represents partial voluming of the most aspect of the internal carotid artery. The infundibulum is midline. Optic chiasm, cavernous sinuses, and suprasellar region appear unremarkable. The remainder of the imaged brain (please note this study has been targeted to the pituitary, and as such the whole brain has not been imaged) appears unremarkable.