80. Which of the following hormones is secreted by anterior pituitary cells that stain with acidic dyes?

A. ACTH B. FSH
C. LH D. Prolactin

E. TSH

ANS. D. The cells of the anterior pituitary can be classified as chromophils (stain
with dyes) or chromophobes (do not stain with dyes). The chromophils can be further divided inacidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils include thesomatotrophs, which secrete growth hormone, and the mammotrophs, which secrete prolactin.The basophils include the corticotrophs, which secrete ACTH (choice A), the gonadotrophs, which secrete FSH and LH (choices B and C), and the thyrotrophs, which secrete TSH (choice E).

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79.The epithelium of the mucous membrane of the mouth is:

A. simple squam. B. strtified squam.

C. simple colum. D. strtified colum.

ANS. B. Squamous cells are flattened, pancake-like cells, and when in layers are known as stratified. The stratified squamous cells lining the mucosa of the oral cavity are similar to those lining the outer skin, although less keratinized. They do, however, flake off continuously into the mouth. Simple squamous tissue would be too thin and not allow for the constant flaking and replacement ^Mcq. Columnar epithelium is found in both the respiratory system and other organs of the digestive system. ^Mcq

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78.The major structural component of the sperm flagellum is the:

A. microtubule
B. microfilament
C. actin filament
D. mysosin filament
E. ciliary body

ANS A. This is a basic histological question of a type found commonly on NBDE, which asks about basic cellular organelles and structures. The sperm cell flagellum is notable for a “9+2” arrangement of fibers formed from microtubules. The 9 single fibers form a circular ring in cross section around the 2 doubled fibers in the center. One of the significant facts about the fibers is
that they are composed of microtubules, made up of tubulin. The other significant fact is that all eucaryotic flagella and cilia have this same structure (for example, cilia form the tracheal lining). Note that procaryotic (bacterial) flagellea do NOT share this structure.


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