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A&P Lab - Week 1/2 Study Guide
Endocrine System
Note: this is not a complete list of terms or concepts to know.
Pituitary:
- pars distalis – very vascular, with three different colors of cells
- acidophils – reddish orange cytoplasm
- basophils – bluish purple, darker than acidophils
- chromophobes – clear or pale cytoplasm
- NOTE: colors refer to cytoplasm only. Nucleus is usually dark.
- pars nervosa – pale, without very many obvious cells. Don’t worry about
finding pituicytes
- pars intermedia – somewhere between the other two. You will not see it
alone. There will always be one or both of the other parts to help you identify.
ADENOHYPOPHYSIS = ANTERIOR PITUITARY (pars distalis +pars tuberalis
+pars intermedia)
NEUROHYPOPHYSIS = POSTERIOR PITUITARY (pars nervosa + neural
stalk)
Pituitary stalk = infundibulum = pars tuberalis +neural stalk.
Thyroid
- look for fluid filled follicles. Fairly easy to identify. Colloid contains
hormone precursors.
- follicular cells – cells which line the follicle and touch the colloid. These cells
make thyroxin
- parafollicular cells – do not touch colloid. Larger and paler than follicular
cells. These cells secrete calcitonin
Parathyroid
- small glands embedded in the thyroid
- chief cells – more abundant, smaller, darker. Secrete PTH
- oxyphil cells – fewer, come in clusters, bigger, paler. Unknown function
- this gland is hard to distinguish from pars distalis. Look for size differences
here, as opposed to color differences in the pituitary.
Adrenal Gland
- capsule – CT layer on the very outside of the cortex. Look for fibers
- zona glomerulosa – first layer in. Cells form arches, secrete
mineralocorticoids
- zona fasiculata – in the middle of the cortex. Cells form straight cords with
sinusoids in between them. Secrete glucocorticoids
- zona reticularis – cells form webwork with sinusoids in between. Usually
darker than the other two layers. Secretes gonadocorticoids
- medulla – cells are bigger than cortical cells. Look for large cells with
prominent nuclei. These are cells of the sympathetic ganglia. Medulla
-
secretes epinephrine and norepinephrine. Note big medullary vein in the
middle to allow easy access to circulation
NOTE: the zones of the cortex are hard to tell apart. You will be given clear
and obvious slides on quizzes, but this still takes practice.
Pancreas
- look for lighter, more disorganized tissue of the Islets of Langerhans. This is
the only way to tell the pancreas from anything else.
- alpha cells – in the islet, secrete glucagon
- beta cells – in the islet, secrete insulin
- NOTE: you do not have to ID these two types of cells specifically. Just
know where they are found and what they secrete.
Thymus
- maturing lymphocytes look like small, dark blue or purple dots throughout the
gland.
- This gland produces thymosin. Important in maturation of killer T-cells
Pineal
- look for dark purple/black concretions of brain sand. Function of brain sand is
unknown
- produces serotonin (during waking) and melatonin (during sleep)
- located in the roof of the third ventricle
Gonads
-
You do not have to ID ovaries or testes histologically today
ovaries produce estrogen and progesterone
testes produce testosterone (produced by Leydig cells)