Template:Endocrine embryo table

Organ	Stage 13	Stage 14	Stage 15	Stage 16	Stage 17	Stage 18	Stage 19	Stage 20	Stage 21	Stage 22	Stage 23
Pineal (Epiphysis)		slight irregularity in surface outline of intact head corresponds to future pineal body (O'Rahilly et al. 1982).	pineal body is detectable in roof of diencephalon (Stadium I of Turkewitsch 1933) (O'Rahilly 1968).	cellular migration in an external direction occurs during stages 16 and 17 (Stadium 2 of Turkewitsch 1933) (O'Rahilly 1968).		cellular migration in pineal body forms a distinct "anterior lobe" where follicles appear (Stadium 3 of Turkewitsch 1933) (O'Rahilly 1973 a).	"anterior lobe" shows a characteristic step and wedge appearance (Stadium 4 of Turkewitsch 1933) (O'Rahilly 1968).				pineal body has reached Stadium 5 of Turkewitsch (1933).
Pituitary (Hypophysis)	basement membranes of craniopharyngeal pouch and brain are clearly in contact (O'Rahilly 1973).	craniopharyngeal pouch is prominent (Streeter 1945) and 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 (O'Rahilly 1973a).		slight indication of the infundibular recess may be seen in some embryos (O'Rahilly 1973 a).	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). Infundibular recess displays a characteristically folded wall, namely the neurohypophysis (O'Rahilly 1973 a).		caudal part of the craniopharyngeal pouch is reduced to a closed epithelial stem (Andersen et al. 1971).	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).	pharyngeal stalk becomes fragmented (Jirfisek 1980)		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.
Thyroid	median thyroid is now bilobed and is connected to the pharynx by a hollow pedicle (Weller 1933). The telopharyngeal body has been regarded as a "lateral thyroid component" by some workers (e.g. Weller 1933).	thyroid pedicle shows further elongation but is still connected to the epithelium of the pharynx (Weller 1933). Right and left lobes and an isthmus may perhaps be presaged (ibid.).	thyroid primordium may be detached from pharyngeal epithelium in some instances. "At about the time" when the thyroglossal duct "becomes broken it loses its lumen" (Grosser 1912).	has lost its continuity with the pharynx and it consists of two lobes, an isthmus, and a remnant of the pedicle (Weller 1933).	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" (Weller 1933).	median thyroid in contact with "lateral thyroid components" (Weller 1933) others maintain that the telopharyngeal body not be regarded as a thyroid component (Bejdl and Politzer 1953). Lobes are "composed of series of continuously communicating solid annectent bars", "the earliest stage of the definitive thyroid" (Weller 1933). First differentiation occurs in "lateral thyroid component," beginning to "blend into uniformly constituted thyroid tissue". Weller (1933) (Fig. 11) shows continuity between its pedicle and pharynx epithelium.		"annectent bars" are more compact then previously (Weller 1933). The thyroid now exhibits its definitive external form.
Parathyroid		"Parathyrogenic zones" (Politzer and Hann 1935) are recognizable (Streeter 1945). The parathyroid 4 primordium has been illustrated at this stage by Weller (1933, Fig. 16).		parathyrogenic zones closely related to third and fourth aortic arches at 9 mm (Politzer and Hann 1935, unstaged embryo). Parathyroid 3 identifiable on anterior wall of third pharyngeal pouch (Weller 1933, Fig. 17) and "does not arise from a dorsal lobule" of pouch and "sudden appearance of well-differentiated clear chief cells in early primordia of parathyroids" at 9 mm (Norris 1937).	parathyroid 4 is attached to the lateral surface of what Weller (1933) termed the "lateral thyroid component"		parathyroid 3 become detached from the pharyngeal endoderm (Jirfisek 1980).	glands are attached to lateral lobes of 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 thymus) Norris (1937, Fig. 4) showed parathyroid 3 rostral to, level with, and caudal to parathyroid 4 in embryos of 16-17 mm.
Thymus‎	Weller (1933) recognized a thymic primordium "of considerable size" on ventral part of third pharyngeal pouch, Norris (1938) considered this stage to be "preprimordial"	Weller's (1933) "thymus" (the third pharyngeal pouch) becomes elongated.		Norris (1938) "not until parathyroid [3] primordium has been outlined can remaining portion of third pouch be recognized, by exclusion, as the primordium of the endodermal thymus".	connection of the thymus with pharynx has been severed and thymus is intimately approximated to cervical duct (Weller 1933). 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 makes contact with thyroid gland and contains a series of canals internally (Weller 1933).		right and left components are in contact with each other (Weller 1933) but are "never completely fused" (Norris 1938, Siegler 1969). Thymic cortex appears (in stages 20-22) as a result, according to Norris (1937).			cortex is well-developed, "true lobulation" has begun with appearance of" fine superficial scallops," lymphocytes are present sparsely in subcortical zone, and vessels are found within thymus (Norris 1938).
Pancreas‎	ventral pancreas may perhaps be distinguishable (Politzer 1952).	ventral pancreas (which may perhaps be distinguishable as early as stage 13) appears as an evagination from the bile duct at stages 14 (Blechschmidt 1973) and 15 (Streeter 1948). Generally described as unpaired but, at least in some cases, may perhaps be bilobed or even multiple (Delmas 1939).			ventral pancreas has now fused with dorsal (Streeter 1948). Perhaps the ventral and dorsal ducts have begun to blend (Russu and Vaida 1959).
Adrenal‎ (Suprarenal)		Cortex - A change in the characteristics of the cells of the coelomic epithelium appears between the mesogastrium and the lateral end of the mesonephros. 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.	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. Jirfisek (1980) denies a mesonephric contribution to the suprarenal. 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.	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. 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.	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). 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.	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.	Cortex - C2 cells lie on gland surface and form a "capsule". Medulla - Sympathicoblasts penetrate the cortex at stages 19 and 20, and form scattered islets of medullary tissue throughout the cortex (Jirfisek 1980).		Cortex - cellular "capsule" becomes covered by a layer of fibrous tissue.	Cortex - C2 cells have changed and resemble fibrocytes.

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