Endocrine is the most histology-heavy unit students consistently underrate — until the first endocrine pathology shows up in their clinical rotation. Each gland has a signature appearance; learning the signatures here saves enormous time later.
Glands on torso + cell types on slides (Pages 2–3)
Gland + principal hormone + target (Page 4)
The dominant rubric for this unit (Page 5)
Graded against the standalone Microscopy Practice rubric
Standard six-item check (Page 6)
3 stations (Page 7)
| Canonical answer | Accepted synonyms | Spelling rule / common confusion |
|---|---|---|
| Brain & head glands | ||
| Hypothalamus | (none) | Endocrine via control of pituitary; not a classic gland but graded with this unit |
| Pituitary gland | Hypophysis | Specify anterior (adenohypophysis) vs posterior (neurohypophysis) when pinned on a section |
| Pineal gland | Pineal body, epiphysis cerebri | Distinguish from pituitary → not yet (pineal is dorsal to thalamus, pituitary is ventral) |
| Neck glands | ||
| Thyroid gland | (none) | Butterfly shape with two lobes + isthmus on the trachea |
| Parathyroid glands | (none) | Four small glands on posterior thyroid; usually represented by markers, not visible structures |
| Trunk glands | ||
| Thymus | (none) | Anterior superior mediastinum; large in children, atrophies in adults |
| Adrenal gland | Suprarenal gland | Pyramidal/triangular cap on superior pole of each kidney; side required if pinned on one |
| Pancreas | (none) | Distinguish endocrine pancreas (islets) from exocrine pancreas (acini) on histology slides |
| Gonadal glands | ||
| Ovary | (none) | Endocrine via estrogen + progesterone; full reproductive role covered in reproductive unit |
| Testis | (none) | Endocrine via testosterone; full reproductive role covered in reproductive unit |
| Canonical answer | Accepted synonyms | Spelling / common confusion |
|---|---|---|
| Pituitary | ||
| Anterior pituitary (adenohypophysis) | Pars distalis (when specifically labeled) | Stains darker than posterior; mixed cell types visible |
| Posterior pituitary (neurohypophysis) | Pars nervosa | Pale-staining; nerve fibers + pituicytes; no glandular cells |
| Acidophil cells (anterior pituitary) | Acidophils | Pink-staining cells; produce GH and prolactin |
| Basophil cells (anterior pituitary) | Basophils | Blue/purple-staining cells; produce TSH, ACTH, FSH, LH |
| Thyroid | ||
| Thyroid follicle | Follicle | Spherical; lined by simple cuboidal/columnar follicular cells; lumen filled with pink colloid |
| Colloid (thyroid) | Thyroid colloid | Pink amorphous material in follicle lumen; stores thyroglobulin |
| Parafollicular cells | C cells | Pale cells between follicles; produce calcitonin |
| Adrenal cortex (3 zones, deep → superficial) | ||
| Zona glomerulosa | (none) | Outermost cortical zone; cells in spherical clusters; produces aldosterone |
| Zona fasciculata | (none) | Middle and largest zone; cells in radial cords; foamy cytoplasm; produces cortisol |
| Zona reticularis | (none) | Innermost cortical zone; cells in irregular network; produces androgens |
| Adrenal medulla | (none) | Central; chromaffin cells; produces epinephrine + norepinephrine |
| Pancreas (endocrine) | ||
| Islet of Langerhans | Pancreatic islet, islet | Pale rounded cluster among darker exocrine acini |
| Alpha cells (islet) | α-cells | Peripheral in islet; produce glucagon |
| Beta cells (islet) | β-cells | Central in islet (most numerous); produce insulin |
| Other tissues | ||
| Pineal gland (corpora arenacea) | Brain sand | Calcified concretions visible in pineal sections; diagnostic feature |
| Hassall corpuscle (thymus) | Thymic corpuscle | Concentric layers of epithelial cells in thymic medulla; diagnostic feature |
For each gland: name principal hormone(s) and target tissue or system. Multi-hormone glands accept any one principal hormone with its target.
| Gland | Principal hormone(s) | Target / function |
|---|---|---|
| Hypothalamus | Releasing hormones (TRH, CRH, GnRH, GHRH); ADH and oxytocin (synthesized here, released from posterior pituitary) | Anterior pituitary; posterior pituitary release sites |
| Anterior pituitary | TSH, ACTH, FSH, LH, GH, prolactin | Thyroid (TSH), adrenal cortex (ACTH), gonads (FSH/LH), bone & soft tissue (GH), mammary glands (prolactin) |
| Posterior pituitary | ADH (vasopressin); oxytocin | Kidney collecting ducts (ADH); uterus + mammary glands (oxytocin) |
| Pineal gland | Melatonin | Sleep–wake cycle; circadian rhythm |
| Thyroid (follicular cells) | T3 (triiodothyronine), T4 (thyroxine) | Metabolic rate of essentially all body tissues |
| Thyroid (parafollicular C cells) | Calcitonin | Lowers blood Ca²⁺ by inhibiting osteoclast activity |
| Parathyroid glands | Parathyroid hormone (PTH) | Raises blood Ca²⁺ via bone resorption, kidney reabsorption, gut absorption (via vit D activation) |
| Thymus | Thymosin (and thymopoietin) | T-lymphocyte maturation |
| Adrenal cortex (zona glomerulosa) | Aldosterone | Kidney; Na⁺ retention, K⁺ excretion, water retention; raises blood pressure |
| Adrenal cortex (zona fasciculata) | Cortisol | Wide systemic effect; raises blood glucose; suppresses inflammation; chronic stress response |
| Adrenal cortex (zona reticularis) | Androgens (DHEA) | Precursor to testosterone and estrogen; minor in adults |
| Adrenal medulla | Epinephrine, norepinephrine | Sympathetic acute stress response; raises HR, BP, blood glucose |
| Pancreas (alpha cells) | Glucagon | Liver; raises blood glucose by stimulating glycogenolysis and gluconeogenesis |
| Pancreas (beta cells) | Insulin | Most cells (especially muscle, adipose, liver); lowers blood glucose by promoting uptake and storage |
| Ovary | Estrogen, progesterone | Reproductive tract development; menstrual cycle; pregnancy maintenance; secondary sex characteristics |
| Testis | Testosterone | Spermatogenesis; secondary sex characteristics; muscle & bone mass |
| Slide | Canonical identification | Two features required |
|---|---|---|
| Pituitary, anterior | Anterior pituitary | Mixed cell types (acidophils + basophils + chromophobes) · Cords of cells separated by sinusoidal capillaries · Stains darker than posterior · Variable cytoplasm color across cells |
| Pituitary, posterior | Posterior pituitary | Pale homogeneous appearance · Unmyelinated nerve fibers + pituicytes · No glandular cells · Often visible Herring bodies (axon terminal swellings storing ADH/oxytocin) |
| Thyroid | Thyroid gland | Spherical follicles · Lined by simple cuboidal/columnar follicular cells · Pink colloid filling lumen · Parafollicular cells between follicles (paler) |
| Adrenal gland | Adrenal gland | Distinct cortex (outer) and medulla (inner) · Cortex shows three zones (glomerulosa = clusters, fasciculata = radial cords, reticularis = network) · Medulla appears more cellular/darker · Capsule on outside |
| Pancreas (with islet) | Pancreas (or islet of Langerhans) | Pale rounded islets among darker exocrine acini (diagnostic) · Islets richly vascularized · Acini have apical zymogen granules · Mixed exocrine + endocrine in same field |
| Pineal gland | Pineal gland | Pinealocytes in clusters · Calcified corpora arenacea (“brain sand”) — diagnostic · Glial cells interspersed |
The endocrine unit asks students to hold three things at once for each gland: where it is, what it looks like, and what it does. Writing the hormone next to the cell type in the sketch is the simplest forcing function. Students who do this in week one can usually answer capstone-level integration questions by week three; students who don’t often can’t.
The endocrine unit contributes 3 stations to the term-end capstone. Each station is 90 seconds; passes at 3 of 4; excellence at 4 of 4.
ID gland. Function: name principal hormone + target. Clinical: one disease of hyper- or hypo-secretion (e.g. Cushing syndrome, hypothyroidism, type 1 diabetes). Integration: relate to one other organ system.
ID gland or specific cell type / zone. Function (per R2). Clinical: one diagnostic finding visible on this histology in disease state (e.g. lymphocytic infiltrate in Hashimoto thyroiditis). Integration: relate the cells visible to the regulatory pathway controlling them (e.g. pituitary basophil → TSH → thyroid follicular cell).
Given a starting hormone or condition, state the feedback loop. Identification: name the axis (e.g. HPA, HPT, HPG). Function: predict the direction of change in the next step. Clinical: one pathology that breaks the loop. Integration: relate the loop to a clinical lab measurement.
| Outcome per station | Counted as |
|---|---|
| 4 / 4 | Excellence (counts toward A bundle) |
| 3 / 4 | Pass (counts toward B and C bundles) |
| ≤ 2 / 4 | Not yet (counts toward D bundle if attempted; no F-bundle credit) |
| No attempt | Not counted toward any bundle |
Student: ______________________________________ Section: _______________ Date: _______________ TA: _______________
| # | Item | ID (R1) | Hormone+target (R2) | Notes |
|---|---|---|---|---|
| 1 | Pituitary anterior or posterior | P / NY | P / NY / — | |
| 2 | Pineal gland | P / NY | P / NY / — | |
| 3 | Thyroid (gland or follicular cells) | P / NY | P / NY / — | |
| 4 | Parathyroid identification | P / NY | P / NY / — | |
| 5 | Adrenal cortex zone | P / NY | P / NY / — | |
| 6 | Adrenal medulla | P / NY | P / NY / — | |
| 7 | Pancreatic islet | P / NY | P / NY / — | |
| 8 | Gonad (endocrine identification) | P / NY | P / NY / — |
| # | Slide | ID | ≥2 features |
|---|---|---|---|
| 9 | Thyroid | P / NY | P / NY |
| 10 | Adrenal (cortex + medulla) | P / NY | P / NY |
| 11 | Pancreas with islet | P / NY | P / NY |
| 12 | Pituitary | P / NY | P / NY |
R4 microscopy overall outcome: P / NY
☐ No ☐ Yes — for item: __________ Tokens remaining: ☐ 3 ☐ 2 ☐ 1 ☐ 0