Pituitary/Pineal Gland: Histology Flashcards
Describe the development of the pituitary gland
Neurohypophysis (posterior lobe) develops from the neural ectoderm. Adenohypophysis (anterior lobe) develops from oral ectoderm aka Rathke’s pouch. Gland sits all cozy in the sella turcica (a depression in the sphenoid bone)
Components of the adenohypophysis (anterior lobe)
Pars tuberalis (wraps around the infundibulum) (Tuberalis+infundibulum=neural stalk fyi)
pars distalis (pars anterior).
Components of the neurohypophysis (posterior lobe)
Pars nervosa, infundibulum (contains the median eminence of tuber cinereum)
Component of the intermediate lobe
Pars intermedia (EASY PEASY POGO STICK)
Name the types of cells in the adenohypophysis (anterior pituitary). If you’re looking at a fuzzy picture, how will you tell them apart?
Chromophobe (lightly stained)
Basophil (blueberry)
Acidophil (pink)
Name the acidophil hormones and their functions (briefly, more detail to come). Go!
Remeber APG. Both are protein hormones.
Prolactin: breast development and milk production
Growth hormone: muscle/bone growth
Name the basophil hormones and their functions. GO GO GO
Remember BFLAT. All proteins.
FSH: follicle development, spermatogenesis
LH: follicle maturation (estrogen/progesterone synthesis) and ovulation. Testosterone synthesis.
ACTH: stimulates release of cortisol, aldosterone and androgens (water/salt balance)
TSH: stimulates release of thyroid hormone (energy balance)
Some extra:
Beta-Endorphin (β-END)
*Beta-Lipotropin (β-LPH)
Chromophobes. Why we care.
Pale staining cells that lack cytoplasmic granules. 4 types:
- Degranulated cells (used to be acidophils/basophils)
- Precursor cells (undifferentiated)
- Apoptotic cells
- Follicular-stellate cells
How big is a mammotroph (prolactin releasing cell)
MAMMOTH SIZED (500-700nm)
How big is a somatotroph (GH releasing cell)
Medium size (300-400nm)
How big is a gonadotroph (FSH, LH releasing cell)
Small size (150-250nm)
How big is a thyrotroph (TSH releasing cell)
Tiny size (120-170nm)
What kind of capillaries do you find in the pituitary?
Fenestrated (little bitty holes in the endothelial cells, complete basement membrane though). This allows hormones to get from the hypothalamus to the pituitary cells via the blood stream. Super duper.
Describe release and feedback control of thyroid hormone
Neuroendocrine cells in the hypothalamus get activated by some neuron. Hypothalamus releases TRH (thyrotropin releasing hormone) to thyrotroph cells in the anterior pituitary. Thyrotroph cells release TSH which stimulates the thyroid follicular cells to release T3/T4 (thyroid hormones). T3/T4 inhibits the thyrotroph cells in the anterior pituritary and the neuroendoendocrine cells of the hypothalamus.
Hormones of the intermediate lobe
Melanocyte-stimulating hormone (MSH)
Opioids (endorphins, dynorphins)
Median eminence. What is it.
Convergence of hypothalamic neurons that release hormones to the posterior pituitary (the infundibulum in particular) via hypophyseal circulation (portal system)
Pituicytes. What is it.
Glial cells of the posterior pituitary. Assist in the storage and release of neurohypophysial hormones
Hormones of the posterior pituitary are produced by….
Paraventricular nucleus and supraoptic nucleus (of the hypothalamus)
Pinealocyte. Vat iz it.
Primary cell of the pineal gland (shocking). A modified neural cell that enzymatically synthesizes melatonin. Melatonin is released at night.
Walk me through how light influences the pineal gland
Light hits the eye, which sends a signal to the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN communicates with the pineal gland via sympathetic pathways and the superior cervical ganglion. Light inhibits melatonin release.
What hormone can cause hyperplasia/hypertrophy of the pituitary gland
Estrogen (PREGGER LADIES)
What hormones are released by the posterior pituitary
ADH and oxytocin. Too easy.
What is a herring body
Accumulation of hormones in the hypothalamic neurons coming to the posterior pituitary. Accumulations are spaced along the length of the axon, not at axon terminal. They are visible under the Chrome Alum hematoxylin stain, and stain blue-gray or purple (think of a blue heron)
The F is a colloid-body
Contained mostly within the pars intermedia, they are remainders of Rathke’s pouch (“collection of protein”). They stain robin egg blue with Martius-Scarlet-Blue stain. Don’t confuse with basophils. Basophils HAVE a nucleus. Colloid-filled cysts HAVE NO nucleus.
What hormones are secreted by the anterior pituitary?
Think: FLAT PiG
FSH
LH
ACTH
TSH
ProlactIn
GH
What kinds of cells do you find in the pars intermedia?
Basophils, Chromophobes and Colloid-cysts
Brain sand. Not to be confused with beach sand that I would like to be sitting in right now.
Also known as the corpora arenacea, these are large mineral deposits found in the pineal gland
Describe the release and feedback control of prolactin
The hypothalamus stimulates the anterior pituitary to release prolactin (TRH and oxytocin also stimulate prolactin release). Prolactin increases dopamine release from the hypothalamus, which inhibits the pituitary from releasing more prolactin.
