Exam 5 Review:  Chapter 27 Testes

scrotum - The external muscular sac of skin enclosing the testes, and into which the testes must descend from the pelvic cavity during embryonic development; it is divided into two chambers by a midline fibrous septum; it contains the dartos and cremaster  muscles which can elevate the testes upon involuntary contraction; having the testes in the scrotum rather than in the abdominal cavity permits them to be cooler than core body temperature, a necessary condition for optimal spermatogenesis.

inguinal canal - A passage in the lower anterior abdominal wall which in the male allows passage of the spermatic cord back into the pelvic cavity from the scrotum; it also represents the path of the descent of the testes during embryonic development; it contains the round ligament in the female; because of its weakness, it is the most frequent site for a hernia.

dartos - The thin layer of smooth muscle located immediately beneath the dermis of the skin of the scrotum; its contraction, which corrugates the scrotal skin for purposes of thermoregulation of the testes because the surface area for heat loss can thus be controlled, is stimulated by sympathetic impulses from the ANS.

cremaster - The skeletal muscle covering the spermatic cord and the testes; it is a derivative of the internal oblique muscle as the spermatic cord passes from the abdomen to the scrotum; it forms the middle covering layer of the spermatic cord as it passes through the canal and distally to the tunica vaginalis; its contraction acts to retract the testes, which keeps them warm and protected from injury.

testes  = testicles - The main male reproductive glands, the male gonads, the source of spermatozoa and of the male sex hormones, the androgens; they are paired organs which descend from the abdominal cavity through the inguinal canal into cavities of the scrotum during fetal life; having them in the scrotum rather than in the abdominal cavity permits them to be cooler than core body temperature, a necessary condition for optimal spermatogenesis; they contain seminiferous tubules where spermatogenesis occurs, a duct system, the straight tubules and rete testis, which leads to the epididymus, and interstitial tissue where interstitial endocrinocytes synthesize androgens.

tunica vaginalis - The serous sheath of the testes and epididymus, derived from the peritoneal lining as the testes descend through the inguinal canal into cavities of the scrotum during fetal life; it consists of an outer parietal and an inner visceral layer which line the spermatic cord.

tunica albuginea - The dense fibrous connective tissue capsule of the testis; septae which extend inward from it divide the testis into lobules.

lobules - The subdivision of a lobed organ; a lobe is often divided up into many lobules; examples of organs with lobules include the lung, liver, testis and breast; in each testis there are 200-300 lobules, each lobule typically contains three seminiferous tubules.

inguinal hernia - The abnormal passage of an internal abdominal organ or structure, often a part of the small intestine, through the inguinal canal; it often occurs due to an increase in abdominal pressure from heavy lifting or other stressful muscular activities; in males, this results in a unilateral bulge in the scrotum; in females this results in a unilateral swelling in the region of the labia majora; some resolve back to normalcy on their own but may return at times of straining or lifting while one which does not go away and causes pain is a surgical emergency.

cryptorchidism - A developmental defect marked by the failure of one or both of the testes to descend into the scrotum.  [Also see The Facts on Undescended Testicles.]

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