11:067:327 Lecture Notes - Lecture 5: Cremaster Muscle, Heat Transfer, Countercurrent Exchange
25 Apr 2016
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Document Summary
Cycles of contraction and relaxation pump spermatozoa into rete tubules. Mediastinum: central connective tissue core houses rete tubules. Rete tubules: transport sperm out of the testes. Host a finite number of germ cells. Iron transport protein required for spermatogenesis. Tight attachments between adjacent cells at lower lateral surfaces of the basal compartment. Form selective permeability barrier to high mw materials + immune cells. Interstitial cells of leydig cells testosterone. In mammals, lower testicular temperature is necessary for spermatogenesis. Testis temperature must be 4-6oc lower than body"s temp. Failure of the testes to descend into the scrotum. Reduced sperm production, common in boars & stall. Skin sweat glands and thermosensitive nerves. Sustained contraction holds testes close to body. Changes scrotal surface area in hot weather. Heat loss enhanced by evaporation of perspiration. Contracts in response to scrotal skin temperature. Development and maintenance of contractility are androgen dependent. Castrate male no tunica dartos contraction. Extends from the inguinal ring to the scrotum.
