Question 13

List the cell types in the anterior pituitary gland. Outline their secretions, control and target organ effects.

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College Answer

Few candidates described cell types as chromophils and chromophobes. There were many errant references to chromaffin cells which are found mainly in the adrenal medulla, and to staining on H&E. Chromophil cells stain by absorbing chromium salts. Few candidates mentioned that the hormones secreted by the anterior pituitary are peptides. Most candidates outlined the hypophyseal-portal system well. Knowledge of TSH and ACTH control and target organ effects were good. Similar knowledge for LH, FSH, PRL and GH was much more sporadic.

Discussion

The "errant references to chromaffin cells" seem to have sown confusion even among the examiners, as it is in fact the chromaffin cells, and not the chromophils and chromophobes, that stain with chromium salts (absorbing them into the dense granules, which then turn brown). The "chromophil" and "chromophobe" classification of pituitary cells refers to "chroma" (χρῶμα), alluding to the way the granulated cells tend to bind pigment with affinity whereas agranular and degranulated cells do not. In their chapter for Theory and Practice of Histological Techniques, Grizzle & Bancroft describe a decent selection of different classical methods for staining pituitary preparations, and only one of them involves chromium salts (the Gomori technique from 1941). All of this of course is completely beside the main point, that is is probably irrelevant for the CICM trainee (who will never stain pituitary slices) to have this information, which means it is also irrelevant to test it in the course of an expensive barrier exam. Nonetheless, in an effort to produce a plausible model answer:

Chromophil cells:
- Acidophils cells:
  - Somatotrophs
  - Mammotrophs
- Basophil cells:
  - Corticotrophs
  - Thyrotrophs
  - Gonadotrophs
Chromophobe cells:
- Amphophils: epithelial cells
- Melanotrophs

Pituitary cells: Secretion, Control, and Target Organ Effects
Cell type	Secreted hormone	Control over secretion	Target organ effects
Somatotrophs	GH	GHRH, somatostatin	Cell proliferation Counter-insulin effects
Mammotrophs	Prolactin	Dopamine, oestrogen	Proliferation of breast exocrine tissue Synthesis of breast milk
Corticotrophs	ACTH	CRH, cortisol	Synthesis of steroids by the adrenal cortex
Thyrotrophs	TSH	TRH, thyroxine	Synthesis and release of thyroid hormones from the thyroid gland
Gonadotrophs	LH, FSH	Oestrogen, testosterone, GNRH	LH stimulates the production of testosterone by Leydig cells in the testes, and the production of estradiol precursors by the ovarian theca cells FSH stimulates spermatogenesis in the male, and ovarian follicle maturation in the female
Melanotrophs	MSH	Pro-opiomelanocortin	Pigmentation of the skin and hair

References

Lechan, Ronald M., and Roberto Toni. "Functional anatomy of the hypothalamus and pituitary." Endotext [Internet] (2016).

Musumeci, Giuseppe, et al. "A journey through the pituitary gland: Development, structure and function, with emphasis on embryo-foetal and later development." Acta histochemica 117.4-5 (2015): 355-366.

Amar, Arun Paul, and Martin H. Weiss. "Pituitary anatomy and physiology." Neurosurgery Clinics 14.1 (2003): 11-23.

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