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Pituitary gland (Most of the orange region is "pars distalis", but the part at the top is "pars tuberalis")
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Median sagittal through the hypophysis of an adult monkey Semidiagrammatic
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Oral Mucosa ( Rathke's Pouch )
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The (also called the '''adenohypophysis''', from Greek ''adeno'', "gland"; ''hypo'', "under"; ''physis'', "growth"; hence, ''glandular undergrowth'') comprises the
Anterior lobe of the
Pituitary Gland and is part of the
Endocrine System . Unlike the
Posterior Lobe , the anterior lobe is genuinely glandular, hence the root ''adeno'' in its name.
Under the influence of the
Hypothalamus , the anterior pituitary produces and secretes several
Peptide Hormone s that regulate many physiological processes including
Stress ,
Growth , and
Reproduction .
The term "pars distalis" is sometimes used as a synonym for the the anterior pituitary, but this is not quite correct. The anterior pituitary is usually divided into three regions:
- Pars Distalis ("distal part") - the majority of the anterior pituitary
- Pars Tuberalis ("tubular part") - a sheath extending up from the pars distalis and wrapping around the Pituitary Stalk
- Pars Intermedia ("intermediate part") - sits between the bulk of the anterior pituitary and the posterior pituitary and is often very small in humans
The function of the tuberalis is not well characterized, and most of the rest of this article refers primarily to the distalis.
Unlike the
Posterior Pituitary (pars nervosa), which originates from neural
Ectoderm , the anterior pituitary arises from an
Invagination of the
Oral Mucosa called
Rathke's Pouch (which is itself ectoderm derived).
This differentiation is exhibited by the fact that while the
Posterior Pituitary merely secretes those hormones produced in the
Hypothalamus (
ADH and
Oxytocin ), the anterior pituitary actually produces its hormones, while being under control of the
Hypothalamus as to when they should be secreted.
A useful acronym for the hormones secreted by the anterior pituitary is 'FLAT PEG' (FSH, LH, ACTH, TSH, Prolactin, Endorphins, GH).
Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the
Hypothalamus . Neuroendocrine neurons in the hypothalamus project
Axon s to the
Median Eminence , at the base of the brain. At this site, these neurons can release substances into small blood vessels that travel directly to the anterior pituitary gland (the hypothalamo-hypophysial portal vessels).
