List the cell types in the anterior pituitary gland. Outline their secretions, control and target organ effects.
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.
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:
|Target organ effects|
|Gonadotrophs||LH, FSH||Oestrogen, testosterone, GNRH||
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Amar, Arun Paul, and Martin H. Weiss. "Pituitary anatomy and physiology." Neurosurgery Clinics 14.1 (2003): 11-23.