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 the 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).	15	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). The infundibular recess displays a characteristically folded wall, namely the neurohypophysis (O'Rahilly 1973 a).	18	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)	22	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 the 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 is in contact with "lateral thyroid components" (Weller 1933) 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" (Weller 1933). This is "the earliest stage of the definitive thyroid" (ibid.). 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.		"annectent bars" of the thyroid are more compact then previously (Weller 1933). The thyroid now exhibits its definitive external form.	21	22	23
Parathyroid	13	"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).	15	parathyrogenic zones are closely related to the third and fourth aortic arches at 9 mm (Politzer and Hann 1935, unstaged embryo). 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 (Norris 1937). The "sudden appearance of well-differentiated clear chief cells in the early primordia of the parathyroids" at 9 mm was emphasized by Norris (1937).	parathyroid 4 is attached to the lateral surface of what Weller (1933) termed the "lateral thyroid component"	18	parathyroid 3 become detached from the pharyngeal endoderm (Jirfisek 1980).	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) showed parathyroid 3 rostral to, level with, and caudal to parathyroid 4 in embryos of 16-17 mm.	21	22	23
Thyroid	13	14	15	16	17	18	19	20	21	22	23
Thyroid	13	14	15	16	17	18	19	20	21	22	23

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