How do hypothalamic hormones reach the pituitary, and does the posterior pituitary really not make oxytocin and vasopressin?
Meera Patel11th Sample
6 Oct 2026 · 1 min read
I have gone through the first section of the endocrine chapter carefully and I have one point that I can't resolve.
NCERT says the hypothalamus contains several groups of neurosecretory cells called nuclei which produce hormones that regulate the synthesis and secretion of pituitary hormones. These are of two types: releasing hormones (which stimulate secretion of pituitary hormones) and inhibiting hormones (which inhibit it). GnRH and somatostatin are the examples. Then it says these hormones reach the pituitary "through a portal circulation" and regulate the anterior pituitary. However, the posterior pituitary is "under the direct neural regulation of the hypothalamus".
In the same chapter, the posterior pituitary (neurohypophysis) is listed as the gland that "secretes" oxytocin and vasopressin. Then there's a line saying they are "actually synthesised by the hypothalamus and transported axonally". I would like to understand this clearly, as I recently met an assertion–reason question, "Oxytocin is secreted by the posterior pituitary" with the reason "the posterior pituitary synthesises it", and I wasn't sure if the assertion is true.
Specific doubts:
- What is the difference between portal circulation and the neural connection, in simple terms?
- Is the assertion true, and is the reason true?
- What are the effects of oxytocin and vasopressin?
7 answers & replies
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[+][–]Tanvi Deshmukh12thSample· 13d ago
The two pathways, in simple words!!
Anterior pituitary (adenohypophysis): the hypothalamic neurons release their hormones (GnRH, somatostatin, etc.) from their nerve endings into a tiny network of blood vessels, the hypophyseal portal system, which carries them straight to the anterior pituitary cells. The cells there are glandular, so they need a chemical message. Releasing hormone → pituitary cell makes and releases its own hormone (like GnRH → LH and FSH). Inhibiting hormone → stops it (somatostatin → stops GH release).
Posterior pituitary (neurohypophysis): it's the end of the hypothalamic neurons' axons, a direct neural connection. No blood portal needed.
[+][–]Mehak AroraDropperSample· 13d ago
I think the assertion is true and the reason is also true. Posterior pituitary = neurohypophysis, and NCERT lists oxytocin and vasopressin as its hormones, so it makes them. Exams just follow NCERT. Isn't that correct?
[+][–]Siddharth RaoDropperSample· 13d ago
Mehak, assertion fine, reason no. The posterior pituitary does not synthesise oxytocin and vasopressin. They're made in the cell bodies of neurosecretory neurons in the hypothalamus, transported down the axons to the posterior pituitary, stored there and released into the blood when those neurons get a nerve signal. So the posterior pituitary is the storing-and-releasing site, not the factory. The correct assertion-reason answer would be "assertion true (it releases them), reason false".
Your Q3: Oxytocin acts on the smooth muscles of the uterus and causes strong contractions during childbirth, and on the mammary glands to cause milk ejection. Vasopressin (ADH) acts mainly on the kidney, promoting water reabsorption from the distal parts of the tubule and reducing water loss (that's why it's called anti-diuretic hormone).
[+][–]Meera Patel11thSample· 13d agoAuthor
Thank you Siddharth. "Stores and releases, not synthesises" is the sentence I needed. I'll mark the assertion true and the reason false.
[+][–]Mehak AroraDropperSample· 13d ago
oops 😅 thanks for correcting me, I was reading only the gland name in the table and not the line below it
[+][–]Nisha Verma12thSample· 13d ago
Since you're doing the pituitary, here's the whole map so it doesn't feel scattered:
- Adenohypophysis: pars distalis (GH, PRL, TSH, ACTH, LH, FSH) and pars intermedia (MSH). In humans the pars intermedia is almost merged with the pars distalis.
- Neurohypophysis: pars nervosa (stores and releases oxytocin and vasopressin).
GH over-secretion → gigantism if it happens in childhood, acromegaly in adults; under-secretion in childhood → pituitary dwarfism. PRL → growth of mammary glands and milk formation. TSH → thyroid, ACTH → adrenal cortex (steroid hormones), LH and FSH → gonads.
[+][–]Rahul DubeyDropperSample· 13d ago
On how I handle the question in the real exam. NCERT's own table puts oxytocin and vasopressin under the neurohypophysis as "stores and releases", and it explicitly says they're synthesised by the hypothalamus. So any option that says "synthesised by posterior pituitary" is a trap. An option "released by posterior pituitary" or "stored in neurohypophysis" is safe.
And remember the NCERT definition of a hormone, because it comes as a direct statement: non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts. The hypothalamus is part of the brain but it works as an endocrine gland too, which is why it's the first gland on the list.
