Embryology & Anatomy

Question 1

• What is a hormone?

Answer 1

A mediator molecular which is released in one part of the body but regulates the function of cells in other parts of the body

Question 2

• Which glands in the body are entirely endocrine?

Answer 2

Pituitary (hypophysis), pineal, thyroid, parathyroids, adrenals

Question 3

• Give an example of a hormone with dual roles?

Answer 3

Dopamine – neurotransmitter (adrenergic receptors to stimulate the heart and blood vessels) & hormone (inhibitory hypothalamic hormone)

Question 4

• What are the two parts of the hypophysis?

Answer 4

Adenohypophysis (glandular – anterior lobe) & neurohypophysis (neural – posterior)

Question 5

• How does the adenohypophysis form?

Answer 5

Upgrowth of ectoderm of roof of the developing mouth (stomodeum)

Question 6

• What is the fate of Rathke’s pouch? • What are the two parts of the hypophysis?

Answer 6

Differentiates into glandular tissue, failure to do so results in pituitary dwarfism

Question 7

• What are the three main sections of the adenohypophysis?

Answer 7

Anterior pituitary lobe – pars tuberalis & pars distalis, intermediate lobe – pars intermedia

Question 8

• What is significant in the horse?

Answer 8

Cleft of hypophysis is absent

Question 9

• How does the neurohypophysis form?

Answer 9

Downgrowth of ectoderm of forebrain, retains connection with brain (infundibulum)

Question 10

• How is the neurohypophysis controlled?

Answer 10

Axons from supraoptic and paraventricular nuclei in hypothalamus form supraopticohypophyseal and paraventriculohypophyseal tracts

Question 11

• How does the thyroid form?

Answer 11

Downgrowth from pharyngeal endoderm of developing tongue at sit of future foramen caecum

Question 12

• What are the hypothalamus, thalamus and pineal gland located?

Answer 12

In the diencephalon

Question 13

• Where is the pituitary gland located?

Answer 13

Beneath the hypothalamus in the sella turcica

Question 14

• Where is the pineal gland located?

Answer 14

Between telencephalic hemispheres, cerebellum and rostral colliculi

Question 15

• What is contained within the follicles of the thyroid?

Answer 15

Follicular cells, parafollicular cells (C-cells) & colloid

Question 16

• Where is the thyroid located?

Answer 16

Around the cranial part of the trachea

Question 17

• How do the internal and external parathyroids form?

Answer 17

Internal parathyroids form from the 4th pharyngeal pouch

External parathyroids form from the 3rd pharyngeal pouch (like the thymus)

Question 18

• Why is the position of the external parathyroids more variable?

Answer 18

Because of their association with the thymus

Question 19

• Where is parathyroid hormone produced?

Answer 19

In the parathyroid by principal (chief) cells

Question 20

• What is they hypophysis closely related to?

Answer 20

R`ostrally – optic chiasma, caudally – mammillary bodies, laterally – cavernous sinus, ventrally – sphenoid bone

Question 21

• What is the blood supply of the thyroid?

Answer 21

Cranial and caudal thyroid arteries & thyroid veins

Question 22

• How do the adrenal glands form?

Answer 22

Cortex from mesoderm between gonadal ridge and mesentery

Medulla from neural crest

Question 23

• How does the pancreas form?

Answer 23

Outgrowth of the foregut, Langerhans islets bud off from the developing exocrine pancreas

Question 24

• List some of the hormones produced in the gut

Answer 24

Gastrin, secretin, cholecystokinin, serotonin, gastric inhibitory polypeptide, somatostatin

Question 25

• What are the main cell types of the endocrine pancreas?

Answer 25

Beta cells -> insulin, alpha cells -> glucagon, delta cells -> somatostatin

Question 26

• What are the three different types of islet cells found in the avian pancreas?

Answer 26

Dark islets -> alpha cells, light islets -> beta cells, mixed islets

Question 27

• What is located in the thoracic aperture of birds?

Answer 27

Thyroid, parathyroid & ultimobranchial body

Question 28

• What is the blood supply to the adrenal glands?

Answer 28

Small arterial branches from neighbouring arteries, medullary central vein collects the blood

Question 29

Where is the 2nd sympathetic neurone located with regards to the adrenal gland?

Answer 29

In the adrenal medulla, adrenal medulla is equivalent to a sympathetic ganglion

Question 30

• Why is there a high concentration of pancreatic hormones in the liver?

Answer 30

Because venous blood from the pancreas runs through the portal vein into the liver