Template:Endocrine embryo table: Difference between revisions

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!  Human Embryonic Endocrine
|+ '''Human Embryonic Endocrine Timeline'''
|-
| Data based on data from O'Rahilly (1983).<ref name=O'Rahilly1983a>{{Ref-O'Rahilly1983a}}</ref>
:::[[Endocrine - Pineal Development‎|Pineal]] (Epiphysis) | [[Endocrine - Pituitary Development‎|Pituitary]] (Hypophysis) | [[Endocrine - Thyroid Development‎|Thyroid]] | [[Endocrine - Parathyroid Development|Parathyroid]] | [[Endocrine - Thymus Development|Thymus‎]] | [[Endocrine - Pancreas Development|Pancreas‎]] | [[Endocrine - Adrenal Development|Adrenal‎]] (Suprarenal)
|-
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| [[Carnegie stage 13|'''Stage 13''']] (week 4)
| [[Carnegie stage 13|'''Stage 13''']] (week 4)
*  [[Endocrine - Pituitary Development‎|Pituitary]] -  basement membranes of the craniopharyngeal pouch and the brain are clearly in contact.<ref name=O'Rahilly1973>{{Ref-O'Rahilly1973}}</ref>
*  [[Endocrine - Pituitary Development‎|Pituitary]] -  basement membranes of the craniopharyngeal pouch and the brain are clearly in contact.<ref name=ORahilly1973>{{Ref-O'Rahilly1973}}</ref>
* [[Endocrine - Thymus Development|Thymus‎]] - Weller (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> recognized already a thymic primordium "of considerable size" on the ventral part of the third pharyngeal pouch, whereas Norris (1938)<ref name=Norris1938>{{Ref-Norris1938}}</ref> considered this stage to be "preprimordial"
* [[Endocrine - Thymus Development|Thymus‎]] - Weller (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> recognized already a thymic primordium "of considerable size" on the ventral part of the third pharyngeal pouch, whereas Norris (1938)<ref name=Norris1938>{{Ref-Norris1938}}</ref> considered this stage to be "preprimordial"
*  [[Endocrine - Thyroid Development‎|Thyroid]] - median thyroid is now bilobed and is connected to the pharynx by a hollow pedicle.<ref name=Weller1933>{{Ref-Weller1933}}</ref> The telopharyngeal body has been regarded as a "lateral thyroid component" by some workers.<ref name=Weller1933>{{Ref-Weller1933}}</ref>
*  [[Endocrine - Thyroid Development‎|Thyroid]] - median thyroid is now bilobed and is connected to the pharynx by a hollow pedicle.<ref name=Weller1933>{{Ref-Weller1933}}</ref> The telopharyngeal body has been regarded as a "lateral thyroid component" by some workers.<ref name=Weller1933>{{Ref-Weller1933}}</ref>
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| [[Carnegie stage 14|'''Stage 14''']] (week 5)
| [[Carnegie stage 14|'''Stage 14''']] (week 5)
*  [[Endocrine - Pineal Development‎|Pineal]] - a slight irregularity in the surface outline of the intact head corresponds to the future pineal body (O'Rahilly et al. 1982).  
*  [[Endocrine - Pineal Development‎|Pineal]] - a slight irregularity in the surface outline of the intact head corresponds to the future pineal body (O'Rahilly et al. 1982).  
*  [[Endocrine - Pituitary Development‎|Pituitary]] - craniopharyngeal pouch is prominent (Streeter 1945) and the notochord appears to be inserted into its dorsal wall. The craniopharyngeal pouch has become elongated and blood vessels are beginning to grow in between the basement membranes of the pouch and brain.<ref name=O'Rahilly1973a>{{Ref-O'Rahilly1973a}}</ref>
*  [[Endocrine - Pituitary Development‎|Pituitary]] - craniopharyngeal pouch is prominent<ref name=Streeter1945>{{Ref-Streeter1945}}</ref> and the notochord appears to be inserted into its dorsal wall. The craniopharyngeal pouch has become elongated and blood vessels are beginning to grow in between the basement membranes of the pouch and brain.<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref>
*  [[Endocrine - Thyroid Development‎|Thyroid]] - thyroid pedicle shows further elongation but is still connected to the epithelium of the pharynx.<ref name=Weller1933>{{Ref-Weller1933}}</ref> Right and left lobes and an isthmus may perhaps be presaged (ibid.).
*  [[Endocrine - Thyroid Development‎|Thyroid]] - thyroid pedicle shows further elongation but is still connected to the epithelium of the pharynx.<ref name=Weller1933>{{Ref-Weller1933}}</ref> Right and left lobes and an isthmus may perhaps be presaged (ibid.).
*  [[Endocrine - Parathyroid Development|Parathyroids]] - "Parathyrogenic zones" <ref name=PolitzerHann1935>{{Ref-PolitzerHann1935}}</ref> are recognizable (Streeter 1945). The parathyroid 4 primordium has been illustrated at this stage by Weller (1933, Fig. 16).
*  [[Endocrine - Parathyroid Development|Parathyroids]] - "Parathyrogenic zones" <ref name=PolitzerHann1935>{{Ref-PolitzerHann1935}}</ref> are recognizable.<ref name=Streeter1945>{{Ref-Streeter1945}}</ref> The parathyroid 4 primordium has been illustrated at this stage by Weller (1933, Fig. 16).
* [[Endocrine - Thymus Development|Thymus‎]] - Weller's (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> "thymus" (the third pharyngeal pouch) becomes elongated.
* [[Endocrine - Thymus Development|Thymus‎]] - Weller's (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> "thymus" (the third pharyngeal pouch) becomes elongated.
* Pancreas - ventral pancreas (which may perhaps be distinguishable as early as stage 13) appears as an evagination from the bile duct at stages 14<ref name=Blechschmidt1973>{{Ref-Blechschmidt1973}}</ref> and 15 (Streeter 1948). It is generally described as unpaired but, at least in some cases, may perhaps be bilobed<ref name=Odgers1930>{{Ref-Odgers1930}}</ref>  or even multiple (Delmas 1939).
* Pancreas - ventral pancreas (which may perhaps be distinguishable as early as stage 13) appears as an evagination from the bile duct at stages 14<ref name=Blechschmidt1973>{{Ref-Blechschmidt1973}}</ref> and 15.<ref name=Streeter1948>{{Ref-Streeter1948}}</ref> It is generally described as unpaired but, at least in some cases, may perhaps be bilobed<ref name=Odgers1930>{{Ref-Odgers1930}}</ref>  or even multiple (Delmas 1939).
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
** Adrenal Cortex - A change in the characteristics of the cells of the coelomic epithelium appears between the mesogastrium and the lateral end of the mesonephros.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
** Adrenal Cortex - A change in the characteristics of the cells of the coelomic epithelium appears between the mesogastrium and the lateral end of the mesonephros.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
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|-
|-
| [[Carnegie stage 15|'''Stage 15''']]
| [[Carnegie stage 15|'''Stage 15''']]
*  [[Endocrine - Pineal Development‎|Pineal]] - pineal body is detectable in the roof of the diencephalon (Stadium I of Turkewitsch<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref> (O'Rahilly 1968).
*  [[Endocrine - Pineal Development‎|Pineal]] - pineal body is detectable in the roof of the diencephalon (Stadium I of Turkewitsch)<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref><ref name=O'Rahilly1968>{{Ref-O'Rahilly1968}}</ref>
*  [[Endocrine - Thyroid Development‎|Thyroid]] - thyroid primordium may be detached from the pharyngeal epithelium in some instances. "At about the time" when the thyroglossal duct "becomes broken it loses its lumen".<ref name=Grosser1912>{{Ref-Grosser1912}}</ref>
*  [[Endocrine - Thyroid Development‎|Thyroid]] - thyroid primordium may be detached from the pharyngeal epithelium in some instances. "At about the time" when the thyroglossal duct "becomes broken it loses its lumen".<ref name=Grosser1912>{{Ref-Grosser1912}}</ref>
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
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| [[Carnegie stage 16|'''Stage 16''']] (week 6)
| [[Carnegie stage 16|'''Stage 16''']] (week 6)
*  [[Endocrine - Pituitary Development‎|Pituitary]] - slight indication of the infundibular recess may be seen in some embryos (O'Rahilly 1973 a).
*  [[Endocrine - Pituitary Development‎|Pituitary]] - slight indication of the infundibular recess may be seen in some embryos.<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref>
*  [[Endocrine - Pineal Development‎|Pineal]] - cellular migration in an external direction occurs in the pineal body during stages 16 and 17 (Stadium 2 of Turkewitsch<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref> (O'Rahilly 1968).
*  [[Endocrine - Pineal Development‎|Pineal]] - cellular migration in an external direction occurs in the pineal body during stages 16 and 17 (Stadium 2 of Turkewitsch)<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref><ref name=O'Rahilly1968>{{Ref-O'Rahilly1968}}</ref>
* Thymus - according to Norris (1938)<ref name=Norris1938>{{Ref-Norris1938}}</ref> , "not until the primordium of the parathyroid [3] has been outlined can the remaining portion of the third pouch be recognized, by exclusion, as the primordium of the endodermal thymus".
* Thymus - according to Norris (1938)<ref name=Norris1938>{{Ref-Norris1938}}</ref> , "not until the primordium of the parathyroid [3] has been outlined can the remaining portion of the third pouch be recognized, by exclusion, as the primordium of the endodermal thymus".
*  [[Endocrine - Parathyroid Development|Parathyroids]] - parathyrogenic zones are closely related to the third and fourth aortic arches at 9 mm unstaged embryo). <ref name=PolitzerHann1935>{{Ref-PolitzerHann1935}}</ref> Parathyroid 3 is identifiable on the anterior wall of the third pharyngeal pouch (Weller 1933, Fig. 17) and "does not arise from a dorsal lobule" of the pouch.<ref name=Norris1937>{{Ref-Norris1937}}</ref>  The "sudden appearance of well-differentiated clear chief cells in the early primordia of the parathyroids" at 9 mm was emphasized by Norris (1937).<ref name=Norris1937>{{Ref-Norris1937}}</ref>
*  [[Endocrine - Parathyroid Development|Parathyroids]] - parathyrogenic zones are closely related to the third and fourth aortic arches at 9 mm unstaged embryo). <ref name=PolitzerHann1935>{{Ref-PolitzerHann1935}}</ref> Parathyroid 3 is identifiable on the anterior wall of the third pharyngeal pouch (Weller 1933, Fig. 17) and "does not arise from a dorsal lobule" of the pouch.<ref name=Norris1937>{{Ref-Norris1937}}</ref>  The "sudden appearance of well-differentiated clear chief cells in the early primordia of the parathyroids" at 9 mm was emphasized by Norris (1937).<ref name=Norris1937>{{Ref-Norris1937}}</ref>
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|-
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| [[Carnegie stage 17|'''Stage 17''']]
| [[Carnegie stage 17|'''Stage 17''']]
*  [[Endocrine - Pituitary Development‎|Pituitary]] - juxtacerebral wall of the craniopharyngeal pouch is the thicker. The lateral lobes (future infundibular, or tuberal, part) and the anterior chamber (Vorraum) are clearly visible (O'Rahilly 1973 a). The infundibular recess displays a characteristically folded wall, namely the neurohypophysis (O'Rahilly 1973 a).
*  [[Endocrine - Pituitary Development‎|Pituitary]] - juxtacerebral wall of the craniopharyngeal pouch is the thicker. The lateral lobes (future infundibular, or tuberal, part) and the anterior chamber (Vorraum) are clearly visible.<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref>The infundibular recess displays a characteristically folded wall, namely the neurohypophysis.<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref>
* Thymus - connection of the thymus with the pharynx has been severed (Weller 1933). The thymus is intimately approximated to the cervical duct (ibid.) According to Norris (1937), both third and fourth pouches make contact with the ectoderm, although only the third "receives an increment from the ectoderm".
* Thymus - connection of the thymus with the pharynx has been severed.<ref name=Weller1933>{{Ref-Weller1933}}</ref> The thymus is intimately approximated to the cervical duct (ibid.) According to Norris (1937), both third and fourth pouches make contact with the ectoderm, although only the third "receives an increment from the ectoderm".
*  [[Endocrine - Parathyroid Development|Parathyroids]] -parathyroid 4 is attached to the lateral surface of what Weller (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> termed the "lateral thyroid component"
*  [[Endocrine - Parathyroid Development|Parathyroids]] -parathyroid 4 is attached to the lateral surface of what Weller (1933)<ref name=Weller1933>{{Ref-Weller1933}}</ref> termed the "lateral thyroid component"
*  [[Endocrine - Thyroid Development‎|Thyroid]]. The lobes of the thyroid curve around the carotid arteries and are connected by a delicate isthmus. Lacunae "should not be confused with lumina of follicles".<ref name=Weller1933>{{Ref-Weller1933}}</ref>
*  [[Endocrine - Thyroid Development‎|Thyroid]]. The lobes of the thyroid curve around the carotid arteries and are connected by a delicate isthmus. Lacunae "should not be confused with lumina of follicles".<ref name=Weller1933>{{Ref-Weller1933}}</ref>
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
** Adrenal Cortex - dorsal part of the whole suprarenal primordium is disorganized by the invasion of sympathetic nerves and cells, while the band of C2 cells and the coelomic epithelium remain intact (Crowder 1957).
** Adrenal Cortex - dorsal part of the whole suprarenal primordium is disorganized by the invasion of sympathetic nerves and cells, while the band of C2 cells and the coelomic epithelium remain intact.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>
* Adrenal Medulla - first neural migration is at its height. Growth of the para-aortic complex is extensive. The plexiform complex is derived from paravertebral sympathetic ganglia T6-12 and usually L 1. Included in it are the primordia of the suprarenal medulla and of the celiac, superior mesenteric, and renal plexuses. Nerve fibres and "paraganglion" (M3) cells enter.
** Adrenal Medulla - first neural migration is at its height. Growth of the para-aortic complex is extensive. The plexiform complex is derived from paravertebral sympathetic ganglia T6-12 and usually L 1. Included in it are the primordia of the suprarenal medulla and of the celiac, superior mesenteric, and renal plexuses. Nerve fibres and "paraganglion" (M3) cells enter.
* Pancreas - ventral pancreas has now fused with dorsal (Streeter 1948). Perhaps the ventral and dorsal ducts have begun to blend (Russu and Vaida 1959).
* Pancreas - ventral pancreas has now fused with dorsal.<ref name=Streeter1948>{{Ref-Streeter1948}}</ref> Perhaps the ventral and dorsal ducts have begun to blend.<ref name=RussuVaida1959>{{Ref-RussuVaida1959}}</ref>
|-bgcolor="F5FAFF"  
|-bgcolor="F5FAFF"  
| [[Carnegie stage 18|'''Stage 18''']] (week 7)
| [[Carnegie stage 18|'''Stage 18''']] (week 7)
*  [[Endocrine - Pineal Development‎|Pineal]] - cellular migration in the pineal body forms a distinct "anterior lobe" in which follicles appear (Stadium 3 of Turkewitsch<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref>) (O'Rahilly 1973 a).
*  [[Endocrine - Pineal Development‎|Pineal]] - cellular migration in the pineal body forms a distinct "anterior lobe" in which follicles appear (Stadium 3 of Turkewitsch)<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref>)<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref>
* Thymus- thymus makes contact with the thyroid gland and contains a series of canals internally (Weller 1933).
* Thymus- thymus makes contact with the thyroid gland and contains a series of canals internally (Weller 1933).
*  [[Endocrine - Thyroid Development‎|Thyroid]] - median thyroid is in contact with "lateral thyroid components"<ref name=Weller1933>{{Ref-Weller1933}}</ref>but others have maintained that the telopharyngeal body should not be regarded as a thyroid component (Bejdl and Politzer 1953). The lobes of the thyroid are "composed of series of continuously communicating solid annectent bars" this is "the earliest stage of the definitive thyroid".<ref name=Weller1933>{{Ref-Weller1933}}</ref>  First differentiation occurs in Weller's (1933) "lateral thyroid component," which is beginning to "blend into uniformly constituted thyroid tissue". Weller (1933) illustrated (Fig. 11) a thyroid gland that still showed continuity between its pedicle and the epithelium of the pharynx.
*  [[Endocrine - Thyroid Development‎|Thyroid]] - median thyroid is in contact with "lateral thyroid components"<ref name=Weller1933>{{Ref-Weller1933}}</ref>but others have maintained that the telopharyngeal body should not be regarded as a thyroid component (Bejdl and Politzer 1953). The lobes of the thyroid are "composed of series of continuously communicating solid annectent bars" this is "the earliest stage of the definitive thyroid".<ref name=Weller1933>{{Ref-Weller1933}}</ref>  First differentiation occurs in Weller's (1933) "lateral thyroid component," which is beginning to "blend into uniformly constituted thyroid tissue". Weller (1933) illustrated (Fig. 11) a thyroid gland that still showed continuity between its pedicle and the epithelium of the pharynx.
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|-
|-
| [[Carnegie stage 19|'''Stage 19''']]
| [[Carnegie stage 19|'''Stage 19''']]
*  [[Endocrine - Pituitary Development‎|Pituitary]] - the caudal part of the craniopharyngeal pouch is reduced to a closed epithelial stem (Andersen et al. 1971).
*  [[Endocrine - Pituitary Development‎|Pituitary]] - the caudal part of the craniopharyngeal pouch is reduced to a closed epithelial stem.<ref name=Andersen1971>{{Ref-Andersen1971}}</ref>
*  [[Endocrine - Pineal Development‎|Epiphysis]] - the "anterior lobe" of the pineal body shows a characteristic step and wedge appearance (Stadium 4 of Turkewitsch<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref>) (O'Rahilly 1968).
*  [[Endocrine - Pineal Development‎|Epiphysis]] - the "anterior lobe" of the pineal body shows a characteristic step and wedge appearance (Stadium 4 of Turkewitsch)<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref>)<ref name=O'Rahilly1968>{{Ref-O'Rahilly1968}}</ref>
*  [[Endocrine - Parathyroid Development|Parathyroids]] - 3 become detached from the pharyngeal endo- derm (Jirfisek 1980).
*  [[Endocrine - Parathyroid Development|Parathyroids]] - 3 become detached from the pharyngeal endoderm.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref>
* Adrenal Cortex - C2 cells lie on the surface of the gland and form a "capsule".<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
* Adrenal Cortex - C2 cells lie on the surface of the gland and form a "capsule".<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
* Adrenal Medulla - Sympathicoblasts penetrate the cortex at stages 19 and 20, and form scattered islets of medullary tissue throughout the cortex (Jirfisek 1980).
* Adrenal Medulla - Sympathicoblasts penetrate the cortex at stages 19 and 20, and form scattered islets of medullary tissue throughout the cortex.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref>
|-bgcolor="F5FAFF"  
|-bgcolor="F5FAFF"  
| [[Carnegie stage 20|'''Stage 20''']] (week 8)
| [[Carnegie stage 20|'''Stage 20''']] (week 8)
*  [[Endocrine - Pituitary Development‎|Pituitary]] - the adenohypophysial epithelium adjacent to the neurohy- pophysis constitutes the beginning pars intermedia (O'Rahilly 1973 a). The walls of the craniopharyngeal pouch bud into the mesenchyme (Andersen et al. 1971 ; Jirfisek 1980).
*  [[Endocrine - Pituitary Development‎|Pituitary]] - the adenohypophysial epithelium adjacent to the neurohy- pophysis constitutes the beginning pars intermedia.<ref name=ORahilly1973a>{{Ref-O'Rahilly1973a}}</ref> The walls of the craniopharyngeal pouch bud into the mesenchyme.<ref name=Andersen1971>{{Ref-Andersen1971}}</ref><ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref>
* Thymus - the right and left components are in contact with each other<ref name=Weller1933>{{Ref-Weller1933}}</ref>  but are "never completely fused"<ref name=Norris1938>{{Ref-Norris1938}}</ref> <ref name=Siegler1969>{{Ref-Siegler1969}}</ref>). Thymic cortex appears (in stages 20-22) as a result, according to Norris
* Thymus - the right and left components are in contact with each other<ref name=Weller1933>{{Ref-Weller1933}}</ref>  but are "never completely fused"<ref name=Norris1938>{{Ref-Norris1938}}</ref> <ref name=Siegler1969>{{Ref-Siegler1969}}</ref>). Thymic cortex appears (in stages 20-22) as a result, according to Norris
(1938), of migration of and covering by "cells derived from the cervical sinus".
(1938), of migration of and covering by "cells derived from the cervical sinus".
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|-
|-
| [[Carnegie stage 21|'''Stage 21''']]
| [[Carnegie stage 21|'''Stage 21''']]
*  [[Endocrine - Pituitary Development‎|Hypophysis]] - the pharyngeal stalk becomes fragmented (Jirfisek 1980).
*  [[Endocrine - Pituitary Development‎|Hypophysis]] - the pharyngeal stalk becomes fragmented.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref>
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
** Adrenal Cortex - the cellular "capsule" becomes covered by a layer of fibrous tissue.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
** Adrenal Cortex - the cellular "capsule" becomes covered by a layer of fibrous tissue.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
|-bgcolor="F5FAFF"  
|-bgcolor="F5FAFF"  
| [[Carnegie stage 22|'''Stage 22''']]
| [[Carnegie stage 22|'''Stage 22''']]
*  [[Endocrine - Parathyroid Development|Parathyroids]] - Parathyroids 4 become detached from the pharyngeal endoderm (Jirfisek 1980).
*  [[Endocrine - Parathyroid Development|Parathyroids]] - Parathyroids 4 become detached from the pharyngeal endoderm.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref>
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
** Adrenal Cortex - the C2 cells have changed and resemble fibrocytes.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
** Adrenal Cortex - the C2 cells have changed and resemble fibrocytes.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
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| [[Carnegie stage 23|'''Stage 23''']]
| [[Carnegie stage 23|'''Stage 23''']]
* Pituitary - adenohypophysis loss of the stalk and lobules of epithelium project into the mesodermal component of the gland, and oriented epithelial follicles are present (Streeter, 1951, plate 2). Abundant angioblasts and capillaries are found.
* Pituitary - adenohypophysis loss of the stalk and lobules of epithelium project into the mesodermal component of the gland, and oriented epithelial follicles are present (Streeter, 1951, plate 2). Abundant angioblasts and capillaries are found.
*  [[Endocrine - Pineal Development‎|Epiphysis]] - The pineal body has reached Stadium 5 of Turkewitsch (1933).<ref name=O'Rahilly1968>{{Ref-O'Rahilly1968}}</ref>
*  [[Endocrine - Pineal Development‎|Epiphysis]] - The pineal body has reached Stadium 5 of Turkewitsch<ref name=Turkewitsch1933>{{Ref-Turkewitsch1933}}</ref><ref name=O'Rahilly1968>{{Ref-O'Rahilly1968}}</ref>
* Thymus - The cortex is well-developed, "true lobulation" has begun with the appearance of" fine superficial scallops," lymphocytes are present sparsely in the subcortical zone, and vessels are found within the thymus (Norris 1938).  
* Thymus - The cortex is well-developed, "true lobulation" has begun with the appearance of" fine superficial scallops," lymphocytes are present sparsely in the subcortical zone, and vessels are found within the thymus.<ref name=Norris1938>{{Ref-Norris1938}}</ref> 
* [[Endocrine - Adrenal Development|Adrenal‎]]
* [[Endocrine - Adrenal Development|Adrenal‎]]
** Adrenal Cortex - It appears that C2 cells first enter the body of the gland at this stage. The pattern of the arterial supply is established. The cellular "capsule" is penetrated by arterial capillaries which join the sinusoids. Their points of entry give the surface of the gland an appearance of cobblestones. The zona glomerulosa is formed of CI and C3 cells. Cells from this zone and from the "capsule" migrate centrally into the cords.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>
** Adrenal Cortex - It appears that C2 cells first enter the body of the gland at this stage. The pattern of the arterial supply is established. The cellular "capsule" is penetrated by arterial capillaries which join the sinusoids. Their points of entry give the surface of the gland an appearance of cobblestones. The zona glomerulosa is formed of CI and C3 cells. Cells from this zone and from the "capsule" migrate centrally into the cords.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>
** Adrenal Medulla - Nerve fibres and neuroblasts are first seen in the body of the gland. The paragangtion (M3) cells are beginning to multiply rapidly and, from 30 mm (stage 23) until birth, some are differentiating into chromaffin cells.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
** Adrenal Medulla - Nerve fibres and neuroblasts are first seen in the body of the gland. The paragangtion (M3) cells are beginning to multiply rapidly and, from 30 mm (stage 23) until birth, some are differentiating into chromaffin cells.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref>  
|-
|-
| Table Data<ref name=O'Rahilly1983a>{{Ref-O'Rahilly1983a}}</ref>
:Links: {{pineal}} (epiphysis cerebri) | {{pituitary}} (hypophysis) | {{thyroid}} | {{parathyroid}} | {{thymus‎}} | {{pancreas‎}} | {{adrenal‎}} (suprarenal)
| '''References'''
| '''References'''
<references/>
<references/>
|}
|}<noinclude>[[Category:Endocrine]][[Category:Timeline]]</noinclude>

Latest revision as of 11:20, 12 May 2018

Human Embryonic Endocrine Timeline
Stage 13 (week 4)
  • Pituitary - basement membranes of the craniopharyngeal pouch and the brain are clearly in contact.[1]
  • Thymus‎ - Weller (1933)[2] recognized already a thymic primordium "of considerable size" on the ventral part of the third pharyngeal pouch, whereas Norris (1938)[3] considered this stage to be "preprimordial"
  • Thyroid - median thyroid is now bilobed and is connected to the pharynx by a hollow pedicle.[2] The telopharyngeal body has been regarded as a "lateral thyroid component" by some workers.[2]
  • Pancreas - ventral pancreas may perhaps be distinguishable.[4]
Stage 14 (week 5)
  • Pineal - a slight irregularity in the surface outline of the intact head corresponds to the future pineal body (O'Rahilly et al. 1982).
  • Pituitary - craniopharyngeal pouch is prominent[5] and the notochord appears to be inserted into its dorsal wall. The craniopharyngeal pouch has become elongated and blood vessels are beginning to grow in between the basement membranes of the pouch and brain.[6]
  • Thyroid - thyroid pedicle shows further elongation but is still connected to the epithelium of the pharynx.[2] Right and left lobes and an isthmus may perhaps be presaged (ibid.).
  • Parathyroids - "Parathyrogenic zones" [7] are recognizable.[5] The parathyroid 4 primordium has been illustrated at this stage by Weller (1933, Fig. 16).
  • Thymus‎ - Weller's (1933)[2] "thymus" (the third pharyngeal pouch) becomes elongated.
  • Pancreas - ventral pancreas (which may perhaps be distinguishable as early as stage 13) appears as an evagination from the bile duct at stages 14[8] and 15.[9] It is generally described as unpaired but, at least in some cases, may perhaps be bilobed[10] or even multiple (Delmas 1939).
  • Adrenal‎
    • Adrenal Cortex - A change in the characteristics of the cells of the coelomic epithelium appears between the mesogastrium and the lateral end of the mesonephros.[11]
    • Adrenal Medulla - paravertebral sympathetic ganglia increase in size as a result of cell division and the addition of nerve fibres from the rami communicantes. The ganglia contain three types of cells: MI, M2, and M3. The M3 cells are the" parasympathetic cells" of Zuckerkandl.[11]
Stage 15
  • Pineal - pineal body is detectable in the roof of the diencephalon (Stadium I of Turkewitsch)[12][13]
  • Thyroid - thyroid primordium may be detached from the pharyngeal epithelium in some instances. "At about the time" when the thyroglossal duct "becomes broken it loses its lumen".[14]
  • Adrenal‎
    • Adrenal Cortex - primordium is first recognizable. A new type of cell (C1) from the coelomic epithelium is found in the subjacent mesenchyme. New cells (C2) appear in the medial wall of mesonephric glomeruli and begin to migrate into the suprarenal primordium.[11][15] denies a mesonephric contribution to the suprarenal.
    • Adrenal Medulla - all types of cells (M1, M2, and M3) increase in number. From stage 15 to stage 18, the suprarenal primordium is cigar-shaped and extends from segment T6 to segment L1, lateral to the aorta and mesogastrium.[11]
Stage 16 (week 6)
  • Pituitary - slight indication of the infundibular recess may be seen in some embryos.[6]
  • Pineal - cellular migration in an external direction occurs in the pineal body during stages 16 and 17 (Stadium 2 of Turkewitsch)[12][13]
  • Thymus - according to Norris (1938)[3] , "not until the primordium of the parathyroid [3] has been outlined can the remaining portion of the third pouch be recognized, by exclusion, as the primordium of the endodermal thymus".
  • Parathyroids - parathyrogenic zones are closely related to the third and fourth aortic arches at 9 mm unstaged embryo). [7] Parathyroid 3 is identifiable on the anterior wall of the third pharyngeal pouch (Weller 1933, Fig. 17) and "does not arise from a dorsal lobule" of the pouch.[16] The "sudden appearance of well-differentiated clear chief cells in the early primordia of the parathyroids" at 9 mm was emphasized by Norris (1937).[16]
  • Thyroid - has lost its continuity with the pharynx and it consists of two lobes, an isthmus, and a remnant of the pedicle.[2]
  • Adrenal‎
    • Adrenal Cortex - Another type of cell (C3) arises from the coelomic epithelium. Both C1 and C3 cells enter the suprarenal primordium. An "enormous immigration" of C2 cells occurs.[11]
    • Adrenal Medulla - cells of neural origin are migrating into the gland, separating the cortical cells into islands. Nerve fibres from the ganglia ac- company the M1 and M3 cells. The M2 cells remain in the ganglia and become sympathetic ganglion cells.[11]
  • Pancreas - dorsal pancreas and the ventral pancreas are contiguous.[8]
Stage 17
  • Pituitary - juxtacerebral wall of the craniopharyngeal pouch is the thicker. The lateral lobes (future infundibular, or tuberal, part) and the anterior chamber (Vorraum) are clearly visible.[6]The infundibular recess displays a characteristically folded wall, namely the neurohypophysis.[6]
  • Thymus - connection of the thymus with the pharynx has been severed.[2] The thymus is intimately approximated to the cervical duct (ibid.) According to Norris (1937), both third and fourth pouches make contact with the ectoderm, although only the third "receives an increment from the ectoderm".
  • Parathyroids -parathyroid 4 is attached to the lateral surface of what Weller (1933)[2] termed the "lateral thyroid component"
  • Thyroid. The lobes of the thyroid curve around the carotid arteries and are connected by a delicate isthmus. Lacunae "should not be confused with lumina of follicles".[2]
  • Adrenal‎
    • Adrenal Cortex - dorsal part of the whole suprarenal primordium is disorganized by the invasion of sympathetic nerves and cells, while the band of C2 cells and the coelomic epithelium remain intact.[11]
    • Adrenal Medulla - first neural migration is at its height. Growth of the para-aortic complex is extensive. The plexiform complex is derived from paravertebral sympathetic ganglia T6-12 and usually L 1. Included in it are the primordia of the suprarenal medulla and of the celiac, superior mesenteric, and renal plexuses. Nerve fibres and "paraganglion" (M3) cells enter.
  • Pancreas - ventral pancreas has now fused with dorsal.[9] Perhaps the ventral and dorsal ducts have begun to blend.[17]
Stage 18 (week 7)
  • Pineal - cellular migration in the pineal body forms a distinct "anterior lobe" in which follicles appear (Stadium 3 of Turkewitsch)[12])[6]
  • Thymus- thymus makes contact with the thyroid gland and contains a series of canals internally (Weller 1933).
  • Thyroid - median thyroid is in contact with "lateral thyroid components"[2]but others have maintained that the telopharyngeal body should not be regarded as a thyroid component (Bejdl and Politzer 1953). The lobes of the thyroid are "composed of series of continuously communicating solid annectent bars" this is "the earliest stage of the definitive thyroid".[2] First differentiation occurs in Weller's (1933) "lateral thyroid component," which is beginning to "blend into uniformly constituted thyroid tissue". Weller (1933) illustrated (Fig. 11) a thyroid gland that still showed continuity between its pedicle and the epithelium of the pharynx.
  • Adrenal‎
    • Adrenal Cortex - gland becomes reorganized. The C1, 2, and 3 cells form cords as sinusoids develop. Cells divide at or near the surface, where new cells are added.[11]
Stage 19
  • Pituitary - the caudal part of the craniopharyngeal pouch is reduced to a closed epithelial stem.[18]
  • Epiphysis - the "anterior lobe" of the pineal body shows a characteristic step and wedge appearance (Stadium 4 of Turkewitsch)[12])[13]
  • Parathyroids - 3 become detached from the pharyngeal endoderm.[15]
  • Adrenal Cortex - C2 cells lie on the surface of the gland and form a "capsule".[11]
  • Adrenal Medulla - Sympathicoblasts penetrate the cortex at stages 19 and 20, and form scattered islets of medullary tissue throughout the cortex.[15]
Stage 20 (week 8)
  • Pituitary - the adenohypophysial epithelium adjacent to the neurohy- pophysis constitutes the beginning pars intermedia.[6] The walls of the craniopharyngeal pouch bud into the mesenchyme.[18][15]
  • Thymus - the right and left components are in contact with each other[2] but are "never completely fused"[3] [19]). Thymic cortex appears (in stages 20-22) as a result, according to Norris

(1938), of migration of and covering by "cells derived from the cervical sinus".

  • Parathyroids - the parathyroid glands are attached to the lateral lobes of the thyroid (Weller 1933).

Weller (1933, Fig. 23) showed parathyroid 3 still rostral to parathyroid 4 at 23 mm, whereas (presumably due to variation in the "descent" of the thymus) (Norris 1937, Fig. 4[16]) showed parathyroid 3 rostral to, level with, and caudal to parathyroid 4 in embryos of 16-17 mm.

  • Thyroid - the "annectent bars" of the thyroid are more compact then previously.[2] The thyroid now exhibits its definitive external form.
Stage 21
  • Hypophysis - the pharyngeal stalk becomes fragmented.[15]
  • Adrenal‎
    • Adrenal Cortex - the cellular "capsule" becomes covered by a layer of fibrous tissue.[11]
Stage 22
  • Parathyroids - Parathyroids 4 become detached from the pharyngeal endoderm.[15]
  • Adrenal‎
    • Adrenal Cortex - the C2 cells have changed and resemble fibrocytes.[11]
Stage 23
  • Pituitary - adenohypophysis loss of the stalk and lobules of epithelium project into the mesodermal component of the gland, and oriented epithelial follicles are present (Streeter, 1951, plate 2). Abundant angioblasts and capillaries are found.
  • Epiphysis - The pineal body has reached Stadium 5 of Turkewitsch[12][13]
  • Thymus - The cortex is well-developed, "true lobulation" has begun with the appearance of" fine superficial scallops," lymphocytes are present sparsely in the subcortical zone, and vessels are found within the thymus.[3]
  • Adrenal‎
    • Adrenal Cortex - It appears that C2 cells first enter the body of the gland at this stage. The pattern of the arterial supply is established. The cellular "capsule" is penetrated by arterial capillaries which join the sinusoids. Their points of entry give the surface of the gland an appearance of cobblestones. The zona glomerulosa is formed of CI and C3 cells. Cells from this zone and from the "capsule" migrate centrally into the cords.[11]
    • Adrenal Medulla - Nerve fibres and neuroblasts are first seen in the body of the gland. The paragangtion (M3) cells are beginning to multiply rapidly and, from 30 mm (stage 23) until birth, some are differentiating into chromaffin cells.[11]
Table Data[20]
Links: pineal (epiphysis cerebri) | pituitary (hypophysis) | thyroid | parathyroid | thymus | pancreas | adrenal (suprarenal)
 References
  1. ↑ O'Rahilly R. Developmental Stages in Human Embryos, Including a Survey of the Carnegie Collection. Part A: Embryos of the First Three Weeks (Stages 1 to 9). (1973) Carnegie Instn. Wash. Publ. 631. Washington, D.C.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Weller GL. Development of the thyroid, parathyroid and thymus glands in man. (1933) Contrib. Embryol., Carnegie Inst. Wash. 24: 93-139.
  3. ↑ 3.0 3.1 3.2 3.3 Norris EH. The morphogenesis and histogenesis of the thymus gland in man: in which the origin of the Hassal's corpuscles of the human thymus is discovered. (1938) Contrib Embryol Carneg Instn 27: 191-207.
  4. ↑ Politzer G. Zur Abgrenzung des Anlagebegriffes, er6rtert an der Friihentwicklung von Parathyreoidea, Pancreas und Thyreoidea (Delineation of the development of the parathyroids, the pancreas, and the thyroid gland). (1952) Acta Anat 15:68-84.
  5. ↑ 5.0 5.1 Streeter GL. Developmental horizons in human embryos. Description of age group XIII, embryos about 4 or 5 millimeters long, and age group XIV, period of indentation of the lens vesicle. (1945) Carnegie Instn. Wash. Publ. 557, Contrib. Embryol., Carnegie Inst. Wash., 31: 27-63.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 O'Rahilly R. The early development of the hypophysis cerebri in staged human embryos. (1973) Anat Rec 175:511.
  7. ↑ 7.0 7.1 Politzer G, Hann F. Uber die Emwicklung der branchiogenen Organe beim Menschen (On the development of the branchiogenic organs in humans). (1935) Z Anat Entw Gesctl 104: 671-708.
  8. ↑ 8.0 8.1 Blechschmidt E. Die prdnatalen Organsysteme des Menschen. (1973) Hippokrates, Stuttgart.
  9. ↑ 9.0 9.1 Streeter GL. Developmental horizons in human embryos. Description of age groups XV, XVI, XVII, and XVIII, being the third issue of a survey of the Carnegie collection. (1948) Contrib. Embryol., Carnegie Inst. Wash. 575, 32: 133-203.
  10. ↑ Odgers PN. Some observations on the development of the ventral pancreas in man. (1930) J. Anat., 65(1): 1-7. PMID 17104298
  11. ↑ 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 11.12 Crowder RE. The development of the adrenal gland in man, with special reference to origin and ultimate location of cell types and evidence in favor of the "cell migration" theory. (1957) Contrib. Embryol., Carnegie Inst. Wash. 36, 193-210.
  12. ↑ 12.0 12.1 12.2 12.3 12.4 Turketwitsch N. Die Entwicklung der Zirbeldrüse des Menschen (The development of the pineal gland in humans). (1933) Morphol Jb 72: 379-445.
  13. ↑ 13.0 13.1 13.2 13.3 O'Rahilly R. The development of the epiphysis cerebri and the subcommissural complex in staged human embryos. (1968) Anat. Rec., 160: 488-489.
  14. ↑ Grosser O. The development of the pharynx and of the organs of respiration. In: F. Keibel, F.P. Mall (ed) Manual of human embryology. (1912) Philadelphia, Lippincott, pp 446-497.
  15. ↑ 15.0 15.1 15.2 15.3 15.4 15.5 Jirásek JE. Human fetal endocrines. (1980) Martinus Nijhoff Publishers BV, The Hague. Springer
  16. ↑ 16.0 16.1 16.2 Norris EH. The parathyroid glands and the lateral thyroid in man: their morphogenesis, histogenesis, topographic anatomy and prenatal growth. (1937) Contrib Embryol Carneg Instn 26: 247-294
  17. ↑ Russu IG and Vaida A. Neue Befunde zur Entwicklung der Bauchspeicheldriise (New findings on the development of pancreatic disease). (1959) Acta Anat 38: 114-125.
  18. ↑ 18.0 18.1 <pubmed>5117462</pubmed>
  19. ↑ Siegler R. The thymus and the unicorn-two great myths of gross anatomy. (1969) Anat Rec. 163: 264.
  20. ↑ O'Rahilly R. The timing and sequence of events in the development of the human endocrine system during the embryonic period proper. (1983) Anat. Embryol., 166: 439-451. PMID 6869855
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