2014 Group Project 6
| 2014 Student Projects | ||||
|---|---|---|---|---|
| 2014 Student Projects: Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6 | Group 7 | Group 8 | ||||
| The Group assessment for 2014 will be an online project on Fetal Development of a specific System.
This page is an undergraduate science embryology student and may contain inaccuracies in either description or acknowledgements. | ||||
The Endocrine System
--Mark Hill (talk) 15:18, 26 August 2014 (EST) OK you have 2 sub-headings after 2 weeks work, and I even had to add the title for your project. How about some content, references, sources for each section. See Lab 3 Assessment.
--Mark Hill (talk) 11:41, 6 September 2014 (EST) Still just references and some of these are not relevant. How about trying to get some timeline info in your project and some fetal endocrine images.
Introduction
--Z3414648 (talk) 15:23, 26 August 2014 (EST)
Pineal gland
<pubmed>9852259</pubmed>
M. Hulsemann, 1971, Development of the Innervation in the Human Pineal Organ, Light and Electron Microscopic Investigations, 115: 396-415
<pubmed>16021838</pubmed>
Hypothalamus
<pubmed>11954031</pubmed>
The hypothalamus plays an important role in the maintenance of homeostasis and the driving of motivated behaviours. Distinct nuclei in the hypothalamus secrete specific hormones that function to regulate thirst, hunger, thermoregulation, circadian rhythms, reproduction and defensive behaviour.
Figure 1. illustrates the location of nuclei in the hypothalamus
[image]
The sexually dimorphic nucleus (SDN, intermediate nucleus) is twice as large in young male adults as in young females. Immediately after birth, only 20% of the SDN cell number is present. During the post-natal period up till two to four years of age cell numbers continue to increase rapidly and equally in both sexes. Past this age, cell numbers start to decrease in girls and this is the point of physiological differentiation in sex.
Neurosecretory cells of the supraoptic (SON) and paraventricular nucleus (PVN) project to the neurohypophysis, where they release vasopressin and oxytocin into the blood circulation. These hormones play an important role in foetal development up till and including the birth process. Foetal oxytocin may initiate or accelerate the course of labor whereas foetal vasopressin plays a role in the adaptation to stress caused by the birth process, by redistribution of the foetal blood flow.
Complications in development of these nuclei regions lead to disorders characteristic to those regions affected.
<pubmed>7643957</pubmed>
Y. Koutcherov, J.K, Mai, G. Paxinos Hypothalamus of the human fetus, Journal of Chemical Neuroanatomy, 26:4, pp 253–270
Pituitary gland
<pubmed>10.1016/j.acthis.2014.04.003</pubmed>
<pubmed>10.1371/journal.pone.0004815</pubmed>
<pubmed>10.1371/journal.pone.0004513</pubmed>
Thyroid
<pubmed>10.1371/journal.pone.0080801</pubmed>
<pubmed>10.1530/JOE-14-0025</pubmed>
<pubmed>10.1371/journal.pone.0016752</pubmed>
Thyroid Development
The functional unit of the thyroid gland is the follicle hence it is necessary to understand how the follicle develops in order to understand the important function of this gland. There are progenitor cells in the anterior endoderm that are specified thyroid progenitor cells and contribute to thyroid organogenesis. The proliferation of these cells results in the formation of a placode along the midline of the pharyngeal floor, just below the future tongue. The left and right lobes of the thyroid gland start off as single structures: buds of endoderm surrounded by mesoderm.
The mammalian thyroid gland is unique in the sense that there is a second endocrine cell called the parafollicular C cell. The progenitor cell for this enters the gland at the stage where there is a fusion between the thyroid progenitor proper and the ultimobranchial bodies. The ultimobranchial bodies arise bilaterally in the most inferior pharyngeal arches and are important in the final organ.
Eventually the midline primordium stretches laterally to reach the ultimobranchial bodies and there is a bilobation event resulting in the recognisable bilobed thyroid gland. [1]
Timeline
How far has the thyroid gland developed by week 8 of gestation?
- Formation of medial anlage (foregut endoderm origin) and 2 lateral anlages (neuroectodermal origin and derivatives of the 4th pharyngeal pouch)
- Budding of ventral pharynx to form thryoid primoridum
- Fusion event of the median anlage with the lateral angales (ultimobranchial bodies) followed by migration of median anlage to it's final pretracheal location
- Sonic hedgehog plays a role in directing correct lobulation of the median anlage into two lobes connected by an isthmus
Fetal Stage of Thyroid Development - from week 8 of gestation onwards:
- Terminal differentiation of thyroid gland occurs from week 7 to 8 of embryo gestation and involves the onset of the gland function
- Pre-colloid stage is week 7-9 and is where the thyroid gland contains strands of compact unpolarised Thyroid Follicular Cell (TFC) precursors
- The beginning colloid stage is week 10-11 and involves the polarisation of the TFC precursors.
- This gives the first appearance of small thyroid follicles (the eventual functional unit of the gland)
- Progressive follicular growth occurs in week 12
- At this point the fetal thyroid gland gains the ability to accumulate iodine and begin thyroid hormone synthesis [2]
Parathyroid gland
<pubmed>22808183</pubmed> <pubmed>22649358</pubmed> <pubmed>21881196</pubmed> <pubmed>21904825</pubmed>
Thymus
<pubmed>21733645</pubmed> <pubmed>20836742</pubmed> <pubmed>21263742</pubmed> <pubmed>512270</pubmed>
Pancreas
<pubmed>22761699</pubmed> <pubmed>22893718</pubmed> <pubmed>24496309</pubmed> <pubmed>24595965</pubmed> <pubmed>23822675</pubmed> <pubmed>22968764</pubmed>
Adrenal gland
<pubmed>7011178</pubmed>
<pubmed>24116052</pubmed>
Gonad development
<pubmed>17237341</pubmed>
<pubmed>7623307</pubmed>
Placenta
<pubmed>10419690</pubmed>
<pubmed>7673080</pubmed>
Timeline
Associated Abnormalities
<pubmed>22808198</pubmed>
