SFP: pituitary histology Flashcards
What are the parts of the pituitary?
The adenohypophysis (anterior pituitary) and neurohypophysis (posterior pituitary)
What are the parts of the adenohypophysis?
Pars distalis
Describe the basic histology of pars distalis.
Cords of glandular epithelium surrounded by fenestrated capillaries that form the secondary plexus of hypothalamo-hypophyseal portal system
What are the types of glandular cells in the pars distalis?
Chromophils and chromophobes. Chromophils stain acidophilic or basophilic while chromophobes will stain the same but very weakly since they are degranulated.
What chromophil types are acidophilic?
Somatotrophs and mammotrophs
What do somatotrophs make?
Growth hormone
Describe mammotrophs.
Basophilic cells in the anterior pituitary that make Prolactin
Describe thyrotrophs.
Basophilic cells in the anterior pituitary that make Thyroid stimulating hormone
Describe corticotrophs.
Basophilic cells in the anterior pituitary that make ACTH
Describe gonadotrophs.
Basophilic cells in the anterior pituitary that make FSH and LH
What is clathrin?
Coat protein used by the trans Golgi to facilitate sorting of secretory proteins into vesicles
Describe fenestrated capillaries.
Contain tight junctions, continuous basal lamina, and fenestrae in the plasma membrane covered by a thin diaphragm. This allows exchange of things like hormones but not larger things like formed elements.
What is the diaphragm in a fenestrated capillary composed of?
Heparin sulfate proteoglycans
Describe pars intermedia.
A narrow strip of glandular epithelial cells between pars distalis and pars nervosa
What does the pars intermedia produce in the fetus?
Melanocyte stimulating hormone
What is produced by pars intermedia?
MSH, b-endorphin, y-lipotropin
What cell types are found in pars intermedia?
Basophils and chromophobes
What are Rathke’s pouch?
What the anterior pituitary is derived from; remnants of the pouch leave fluid-filled cysts.
Describe pars tuberalis.
Glandular epithelial cells surrounding the infundibular stalk
What cell types are in the pars tuberalis?
Basophils and chromophobes
What hormones are secreted by the pars tuberalis?
FSH and LH
Briefly describe the neurohypophysis.
Not a true gland, so doesn’t contain secretory cells, it is neural tissue that contains unmyelinated axons derived from secretory neurons and receives hormones from the hypothalamus.
Describe neurons in the neurohypophysis.
The cell body is found in the hypothalamus, and the axons extend into the neurohypophysis.
What are herring bodies?
Dilations of axon terminals containing secretory granules produced in the neuronal body. These are found in the neurohypophysis.
What are pituicytes?
Specialized glial cells in the neurohypophysis
What hormones are associated with the neurohypophysis?
Oxytocin and ADH
What is neurophysin?
A carrier protein that binds to/transports hormones to the posterior pituitary from the hypothalamus; they are synthesized together and then cleaved.
Oxytocin binds ___
Neurophysin I
ADH binds ___
Neurophysin II
