Micro of Endocrine Glands - Pituitary Gland

Question 1

List two other names for the Pituitary Gland

Answer 1

1. Hypophysis 2. Hypophysis cerebri

Question 2

Gross anatomy of pituitary gland

Answer 2

1. Attached to hypothalamus (diencephalon) via thin stalk 2. Lies in sella turcica of basisphenoid bone 3. Composed of two portions: adenohypophysis + neurohypophysis

Question 3

Another name for adenohypophysis more commonly used in human anatomy

Answer 3

Anterior pituitary or anterior lobe of the pituitary gland

Question 4

Another name for neurohypophysis, more commonly used in human anatomy

Answer 4

Posterior pituitary or posterior lobe of the pituitary gland

Question 5

Embryology of Pituitary Gland - Infundibulum

Answer 5

• Evagination of diencephalon (neural ectoderm)
• funnel shaped, grows ventrally to form the neurohypophysis
• Neurohypophysis remains attached to the brain

Question 6

Embryology of Pituiatry - Adenohypophyseal Pouch

Answer 6

• Aka Rathke’s Pouch
• Evagination of oral ectoderm
• Lining of oral cavity forms a pouch and grows dorsally towards the downgrowing poriton of the infundibulum to form the adenohypophysis
• Adenohypophysis will eventually lose contact with the oral ectoderm completely

Question 7

Which one is the infundibulum which will form ______.

Which one is Rathke’s Pouch (Adenohypophyseal pouch) which will form ______.

Answer 7

Blue - infudnibulum, which will form the neurohypophysis

Green - Adenohypophyseal pouch which will form the adenohypophysis

Question 8

Anatomy of Neurohyphysis

Answer 8

• Infudibulum divided into two parts
  
  • Median eminence = “tuber cenarium” - slightly swollen area at the attachement to the hypothalamus
  • Stem or stalk
• Neural lobe = pars nervosa - very distal end of infudibulum becomes the neural lobe
• Infundibular recess - extension of 3rd ventricle of variable distance into the neurohypophysis

Question 9

Anatomy of Adenohypophysis

Answer 9

• Pars distalis - most significant, terminal (most ventral) swelling
• Pars tuberalis - extension of pars distlalis that surrounds the stalk of pituitary
• Pars intermedia - narrow strip of tissue located between pars nervosa of nueral hypophysis and pars distalis
• Hyophyseal cavity - space between pars distalis and pars intermedia; reminant of the lumen of Rathke’s pouch

Question 10

All vessels that feed the pituitary gland are dervied from _______, and enter pituitary gland as _______.

Answer 10

1. Cerebral arterial circle
2. Hypophyseal arteries

Question 11

Blood supply to infundibulum and adenohypophysis

Answer 11

• Cerebral arterial circle –>
• Hypophyseal arteries –>
• Hypophyseal portal system
  
  • Hypophyseal Aa. form a primary capillary plexus in the median eminence, which drain into hypophyseal portal veins
  • Portal Vv. form secondary capillary plexus in the pars distalis

Hypophyseal Aa enter median eminence –> primary capillary plexus –> hypophyseal portal veins –> secondary capillary plexus in pars distalis

Question 12

Blood supply to Neural lobe = pars nervosa

Answer 12

Pars nervosa has its own hypophyseal arteries, separate from the blood supply to the infundibulum and adenohyphosis.

• Cerebral arterial circle –>
• Hypophyseal arteries –>
• Capillary plexus –>
• Drain into own separate veins

**NOT supplied by hypophyseal portal system as the rest of the pituitary gland is

Question 13

Cells of adenohypophysis identified by the Orange G - PAS staining method

Answer 13

1. Chromophobes - do not take up any of the dye, nucleus can be seen, but cytoplasm looks clear
2. Chromophils - color loving, take up one of the two dyes
   
   • Acidophils (yellow staining granules in cytoplasm)
   • Basophils (red staining granules in cytoplasm)

Question 14

Acidophils and basophils occur in large numbers, mostly in what part of the adenohypophysis?

Answer 14

Pars distalis

Question 15

Two types of acidophils that are identified by immunological methods:

Answer 15

1. Somatotropic cells
2. Mammotropic cells

Question 16

Three types of basophils that are identified by immunological methods

Answer 16

1. Thyrotropic cells
2. Gonatdotropic cells
3. Corticotropic cells

Question 17

Somatotropic cells

Answer 17

• Acidophil
• Produce growth hormone = somatotropin
  
  • Protein
  • Metabolic effects of almost every cell in the body
  • Stimulates growth of epiphyseal carilages of long bones via somatomedins (produced by liver)
    
    • Growth hormones effect epiphyseal cartilages indirectly via somatomedins

Question 18

Mammotropic cells

Answer 18

• Acidophil
• Produce prolactin = lactogenic hormone
  
  • Protein
  • Stimulates mammary development during pregnancy
  • Promotes lactation - necessary for normal milk production after birth
  • Stimulates maternal behavior

Question 19

Thyrotropic cells

Answer 19

• Basophilic
• Produce TSH = Thyroid Stimulating Hormone = thyrotropin
  
  • Glycoprotein
  • Stimulates synthesis + release of thyroid hormones (T3 and T4)
    
    • Stimulates thyroid to release these thyroid hormones

Question 20

Gonadotropic Cells

Answer 20

• Basophilic
• Two gonadotropic cells:
  
  • Produce follicle stimulating hormone (FSH)
    
    • Glycoprotein
    • Stimulates spermatogenesis in males
    • Stimulates early follicular development in female
  • Produce Luteinizing hormone (LH)
    
    • Glycoprotein
    • Simulates follicular maturation + ovulation
    • Stimulates corpus luteum –> progesterone
    • Stimulates testosterone secretion in males

Question 21

Corticotropic cells

Answer 21

• Basophils
• Produce adrenocorticotropic hormone = ACTH = Corticotropin
  
  • Polypeptide
  • Stimulates synthesis + release of glucocorticoids and androgens from both female and male adrenal cortex

Question 22

Chromophobes of adenohypophysis

Answer 22

Degranulated forms of acidophils and basophils, they have released their contents via exocytosis and have not yet synthesized a new complement of granules yet

NOT a sepcific cell type