1. Comparative Anatomy Endocrine Organs
Kardong
Chapter 15
Part 17

2. Endocrine Organs Ductless organs Secrete hormones
Derived from the 3 germ layers

3. Pituitary Gland
Figure Phylogeny of the vertebrate pituitary.

4. Pituitary Gland (Hypophysis)
Derived from ectoderm
Two divisions
Neurohypophysis (post. pit.)
Adenohypophysis (ant. pit.)
Figure Anterior and posterior pituitary.

5. Pituitary Gland (cont.’d)
Neurohypophysis
Infundibulum of diencephalon
Stores hormones
Adenohypophysis
Cells evaginate away from stomadeum
Secretes hormones
Rathke’s Pouch
Figure Embryogenesis of the amniote pituitary .

6. Caudal Neurohemal Organ
Endocrine gland unique to some fish (teleosts and elasmobranchs)
Urophysis
Neurosensory organ (releases neurosecretions = neurohormones)
Occurs at tip of tail off of spinal cord
Figure Urophysis (caudal neurohemal organ).

7. Pineal Derived from ectoderm Produces melatonin Gonadal regulator
Photoperiodism
Figure Location of the pineal gland in the human brain.

8. Derived from Mesoderm
Figure Adrenal gland tissue in lower vertebrates.

9. Figure 17.7. Adrenal gland tissue in higher vertebrates.

10. Adrenal Gland (cont.’d)
Adrenal cortex (steroidogenic)
Derived from mesoderm
Adrenal medulla
Derived form ectoderm
From neurocrest cells
(aminogenic)
Figure Cross section of adrenal gland (top) and anatomical position of the adrenal glands.

11. Gonads Derived from mesoderm
Within kidney tissue in some ray-finned fish
Corpuscles of Stannius (inhibits calcium uptake); in large salmon, can be 0.5 mm in diameter; also found in Amia (40-50 in number)

12. Figure 17.9. Vertebrate thyroid morphology in vertebrates.

13. Figure 17.10. Pancreas and islets of Langerhans.

14. Endodermal Origin Pancreatic Islets of Langerhans Thyroid gland
Foramen cecum- reminant of thyroid invagination
Bursa of Fabricius
Outpocket of cloaca
Thymus in nature
Figure Mammalian thyroid development.

15. Pharyngeal Pouches Derived from endoderm Fish
Pouches 2, 3, 4, 5 (dorsal)- thymus
Pouch 5 (ventral)- ultimobranchial bodies
Amphibians
Pouches 3, 4, 5 (dorsal)- thymus
Figure Contributions of the embryonic pharyngeal pouches to development of endocrine glands.

16. Pharyngeal Pouches (cont.’d)
Mammals
Pouches 3 & 4 (dorsal)- thymus
Pouches 3 & 4 (ventral)- parathyroids
No ultimobranchial bodies (incorporated directly into the thyroid as parafollicular cells – C cells)
Figure Contributions of the embryonic pharyngeal pouches to development of endocrine glands.

17. The End