Endocrine - Pituitary Development
Introduction
Historically, this endocrine gland was called the "pituitary" as it was originally thought to produce mucous that discharged through the nose. We now know that this is not the function of the pituitary, or hypophysis which is an endocrine gland links the brain to peripheral endocrine organs and systems of the body through several specific hormones. The developmental origin of the hypophysis is also unique, epithelial origins from neural ectoderm (posterior) and from surface ectoderm (anterior).
During development, the boundary epitheilal ectoderm in the roof of the pharynx forms a pocket (Rathke's pouch) that comes into contact with the ectoderm of developing brain. Rathke's pouch is named after German embryologist and anatomist Martin Heinrich Rathke (1793 — 1860).
Anatomically, the pituitary has 2 main parts posterior, or neurohypophysis and anterior, or adenohypophysis (the pars distalis, pars intermedia, and pars tuberalis). Between the two a specialized vascular (portal) system allows communication from the brain to peripheral endocrine organs and other systems. File:17thC-turkish-saddle3.jpg
The pituitary is located within the pituitary fossa of the sphenoid bone, anterior to the lamina terminalis and superior to the pharynx. The shape of the bone surrounding the pituitary led to the naming sella turcica (Latin sella = saddle, turcica = Turkish), as it resembled a saddle shape.
Pit1 (pituitary-specific transcription factor) is a transcription factor important for pituitary development and muations in this gene can lead to abnormalities in pituitary development and hormone production. (More? [../MolDev/factor/pit.htm Molecular Development Factors - Pit])
Anterior pituitary hormones - Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Somatotrophin/growth hormone (GH), Prolactin (PRL), Melanocyte-stimulating hormone (MSH)
Posterior pituitary hormones - Oxytocin, Arginine vasopressin
| Lecture - Head Development | original page
Development Overview
- Dual ectoderm origins
- Ectoderm - ectoderm roof of stomodeum, Rathke's pouch, adenohypophysis
- Neuroectoderm - prosenecephalon then diencephalon, neurohypophysis
Adenohypophysis
- Anterior wall proliferates - pars distalis
- Posterior wall little growth – pars intermedia
- Rostral growth around infundibular stem – pars tuberalis
Neurohypophysis
- Infundibulum – median eminence, infundibulum, pars nervosa
Development Timeline
- Week 4 – hypophysial pouch, Rathke’s pouch, diverticulum from roof
- Week 5 – elongation, contacts infundibulum, diverticulum of diencephalon
- Week 6 – connecting stalk between pouch and oral cavity degenerates
- Week 10 – growth hormone and ACTH detectable
- Week 16 – adenohypophysis fully differentiated
- Week 20 to 24 – growth hormone levels peak, then decline
Pituitary Timeline
- Week 4 - hypophysial pouch, Rathke’s pouch, diverticulum from roof
- Week 5 - elongation, contacts infundibulum, diverticulum of diencephalon
- Week 6 - connecting stalk between pouch and oral cavity degenerates
- Week 10 - growth hormone and ACTH detectable
- Week 16 - adenohypophysis fully differentiated
- Week 20 to 24 - growth hormone levels peak, then decline
References
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Cite this page: Hill, M.A. (2024, June 1) Embryology Endocrine - Pituitary Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_-_Pituitary_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G