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|+ '''Human Embryonic Endocrine Timeline''' | |||
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| [[Carnegie stage 13|'''Stage 13''']] (week 4) | | [[Carnegie stage 13|'''Stage 13''']] (week 4) | ||
* [[Endocrine - Pituitary Development| | * [[Endocrine - Pituitary Development|Pituitary]] - basement membranes of the craniopharyngeal pouch and the brain are clearly in contact.<ref name=ORahilly1973>{{Ref-O'Rahilly1973}}</ref> | ||
* 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) 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> | ||
* Pancreas - ventral pancreas may perhaps be distinguishable | * Pancreas - ventral pancreas may perhaps be distinguishable.<ref name=Politzer1952>{{Ref-Politzer1952}}</ref> | ||
|-bgcolor="F5FAFF" | |-bgcolor="F5FAFF" | ||
| [[Carnegie stage 14|'''Stage 14''']] (week 5) | | [[Carnegie stage 14|'''Stage 14''']] (week 5) | ||
* [[Endocrine - | * [[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<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.). | ||
* 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> | * [[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). | ||
* 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | * [[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.<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]] | |||
** 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 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | |||
|- | |- | ||
| [[Carnegie stage 15|'''Stage 15''']] | | [[Carnegie stage 15|'''Stage 15''']] | ||
* [[Endocrine - Pineal Development| | * [[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" | * [[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> | ||
* 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | * [[Endocrine - Adrenal Development|Adrenal]] | ||
* 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | ** 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref><ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref> 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | |||
|-bgcolor="F5FAFF" | |-bgcolor="F5FAFF" | ||
| [[Carnegie stage 16|'''Stage 16''']] (week 6) | | [[Carnegie stage 16|'''Stage 16''']] (week 6) | ||
* [[Endocrine - Pituitary Development| | * [[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| | * [[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), "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 | * [[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 - Thyroid Development|Thyroid]] - has lost its continuity with the pharynx and it consists of two lobes, an isthmus, and a remnant of the pedicle.<ref name=Weller1933>{{Ref-Weller1933}}</ref> | * [[Endocrine - Thyroid Development|Thyroid]] - has lost its continuity with the pharynx and it consists of two lobes, an isthmus, and a remnant of the pedicle.<ref name=Weller1933>{{Ref-Weller1933}}</ref> | ||
* Adrenal Cortex | * [[Endocrine - Adrenal Development|Adrenal]] | ||
* 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | ** 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | ||
** 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | |||
* Pancreas - dorsal pancreas and the ventral pancreas are contiguous.<ref name=Blechschmidt1973>{{Ref-Blechschmidt1973}}</ref> | * Pancreas - dorsal pancreas and the ventral pancreas are contiguous.<ref name=Blechschmidt1973>{{Ref-Blechschmidt1973}}</ref> | ||
|- | |- | ||
| [[Carnegie stage 17|'''Stage 17''']] | | [[Carnegie stage 17|'''Stage 17''']] | ||
* [[Endocrine - Pituitary Development| | * [[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 | * 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> | ||
* 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 | * [[Endocrine - Adrenal Development|Adrenal]] | ||
* 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 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> | ||
* Pancreas - ventral pancreas has now fused with dorsal | ** 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.<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| | * [[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. | ||
* 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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | * [[Endocrine - Adrenal Development|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.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | |||
|- | |- | ||
| [[Carnegie stage 19|'''Stage 19''']] | | [[Carnegie stage 19|'''Stage 19''']] | ||
* [[Endocrine - Pituitary Development| | * [[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 | * [[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 | * [[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 | * 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| | * [[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" | * 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". | ||
* [[Endocrine - Parathyroid Development|Parathyroids]] - the parathyroid glands are attached to the lateral lobes of the thyroid (Weller 1933). | * [[Endocrine - Parathyroid Development|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 | 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<ref name=Norris1937>{{Ref-Norris1937}}</ref>) showed parathyroid 3 rostral to, level with, and caudal to parathyroid 4 in embryos of 16-17 mm. | ||
* [[Endocrine - Thyroid Development|Thyroid]] - the "annectent bars" of the thyroid are more compact then previously.<ref name=Weller1933>{{Ref-Weller1933}}</ref> The thyroid now exhibits its definitive external form. | * [[Endocrine - Thyroid Development|Thyroid]] - the "annectent bars" of the thyroid are more compact then previously.<ref name=Weller1933>{{Ref-Weller1933}}</ref> The thyroid now exhibits its definitive external form. | ||
|- | |- | ||
| [[Carnegie stage 21|'''Stage 21''']] | | [[Carnegie stage 21|'''Stage 21''']] | ||
* [[Endocrine - Pituitary Development|Hypophysis]] - the pharyngeal stalk becomes fragmented | * [[Endocrine - Pituitary Development|Hypophysis]] - the pharyngeal stalk becomes fragmented.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref> | ||
* Adrenal Cortex - the cellular "capsule" becomes covered by a layer of fibrous tissue.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | * [[Endocrine - Adrenal Development|Adrenal]] | ||
** 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 | * [[Endocrine - Parathyroid Development|Parathyroids]] - Parathyroids 4 become detached from the pharyngeal endoderm.<ref name=Jirasek1980>{{Ref-Jirasek1980}}</ref> | ||
* Adrenal Cortex - the C2 cells have changed and resemble fibrocytes.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | * [[Endocrine - Adrenal Development|Adrenal]] | ||
** Adrenal Cortex - the C2 cells have changed and resemble fibrocytes.<ref name=Crowder1957>{{Ref-Crowder1957}}</ref> | |||
|- | |- | ||
| [[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 | * [[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 | * 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> | ||
* 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> | * [[Endocrine - Adrenal Development|Adrenal]] | ||
* 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 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> | |||
|- | |- | ||
| 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/> | ||
|} | |}<noinclude>[[Category:Endocrine]][[Category:Timeline]]</noinclude> |
Latest revision as of 11:20, 12 May 2018
Stage 13 (week 4)
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Stage 14 (week 5)
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Stage 15
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Stage 16 (week 6)
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Stage 17
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Stage 18 (week 7)
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Stage 19
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Stage 20 (week 8)
(1938), of migration of and covering by "cells derived from the cervical sinus".
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. | |
Stage 21
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Stage 22
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Stage 23
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Table Data[20] | References
|