Endocrine Flashcards
(16 cards)
Why are rodents often used in studies of the endocrine system?
Studies investigating the mechanisms often require the sacrifice of a large numbers of experimental animals.
Describe the location of the hypophysis in the rodent.
Rodents possess an almost flat sella turcia. Position of hypophysis under midbrain is on midline at a point perpendicular to a line joining openings of the auditory canals. Becomes displaced rostrally as rat grows older.
What are the approaches for a hypophysectomy?
Transauricular and parapharyngeal.
Describe the parapharyngeal approach of a hypophysectomy? What improves survival post-op?
Ventral midline incision on neck, retraction of salivary glands, omohyoid, and trachea, and removal of periosteum centered at occipitosphenoidal synchondrosis. Burr hole is made and hypophysis is aspirated.
Survival rates improved when 5% glucose or tetracycline is used 3 days postop. Drinking water supplemented with 5-10% glucose for duration of study.
Describe a pinealectomy approach.
Longitudinal skin incision over cranium, periosteum is scraped from the area to be drilled, and dental drill creates a burr hole over the right cerebral hemisphere at the junction of the saggital and lamboid sutures. Dura incised, superior saggital vein doubly ligated and resected to expose gland, and pineal gland is removed with blunt tipped, curved, iris scissors.
Why is bilateral adrenalectomies an uncommon technique in clinical practice? What is the exception?
Causes severe physiologic changes that are difficult to correct with replacement therapy.
Ferret is the exception, in which adrenal gland tumors are prevalent and staged unilateral adrenalectomies and subtotal bilateral adrenalectomies are established.
What do bilaterally adrenalectomized water require?
Normal saline as a water source.
Where is the murine thyroid located?
Cranioventral cervical region, deep in cervical musculature and directly superficial to the cricoid cartilage and first four tracheal rings.
What should mice receive following thyroidectomy? Why?
2% calcium lactate solution for at least 7 days bilaterally. Some parathyroids are invariably removed.
What structure must not be damaged in removal of the thyroids/parathyroids?
Recurrent laryngeal nerve
What is required to produce a hypothyroid state in GPs?
Surgical thyroidectomy produces a temporary hypothyroid state. Long-term requires additional use of 131I.
Where are parathyroids found in GPs?
Not always attached to the thyroid.
What is a biomarker for successful parathyroidectomy?
Reduction in serum calcium concentrations.
Describe the murine thymus.
Asymmetrically bilobed, mediastinal organ lying from thoracic inlet to heart base.
How is the thymus accessed for thymectomy? What does this create, and how is it fized?
Thoracotomy. Produces a pneumothorax. Reestablishment of negative pressure is achieved via compression of the chest via surgical closure.
What is an alternative approach to thymus removal?
Dissection of thoracic inlet with elevation of manubrium and suction removal of each thymic lobe.
