DIRECTIONS FOB LABORATORY WORK 805 



chromosomes in the metaphase plates of : a, the dividing spermogonium ; 

 b, the primary spermocyte ; c, the secondary spermocyte. Note the acces- 

 sory or sex chromosome. What is its position and behavior in: a, the 

 resting primary spermocyte; b, the dividing primary spermocyte; c, the 

 resting and dividing secondary spermocytes ; d, the spermatid ? What is 

 its probable significance with respect of sex determination ? sex control ? 

 How do the maturation mitoses differ from ordinary somatic cell di- 

 vision? Significance of this difference from the standpoint of inher- 

 itance? Probable significance of the chromosomes? 



(5) THE SPERMATOZOON (spermozoon; spermium; sperm). Sketch 

 (306) from a stained section under the oil immersion lens a human 

 spermatozoon. Compare with a cover-glass preparation of preserved 

 sperm. Identify: a, head (with perforatorium, consisting of acrosome 

 and galea capitis) ; b, neck; c, middle piece or body (with distal cen- 

 trosome, end ring, central filament and spiral filament) ; d, tail; and e, 

 terminal filament. 



Compare with spermium of dog and mouse, and some other mammal 

 (e.g., opossum). 



From what constituents of the spermatid are the several above- 

 enumerated portions of the fully developed spermium derived? 



Origin, function and fate (in fertilization) of: a, the head; b, the 

 middle piece (with its centrosome and mitochondrial spiral filament) ; 

 and c, the tail? 



(6) THE INTERSTITIAL CELLS (of Leydig). Identify among the in- 

 ter tubular connective tissue (testicular stroma) the interstitial cells. 

 Sketch (307) several adjacent cells. Origin, structure, probable func- 

 tion and fate? Condition of the interstitial cells, and of the seminal 

 (epithelium, in cryptorchism ? 



(B) THE DUCT SYSTEM OF THE TESTIS. 



(1) TUBULI EECTI. Sketch (308) h.p. a segment of the wall of 

 a tubulus rectus at the point of transition to the tubulus contortus. 

 With what cells of the latter tubule are the lining cells of the tubulus 

 rectus homologous? 



(2) RETE TESTIS. Study l.p. the mediastinum of the testis with 

 its included rete tubules. Sketch (309) a small area. Make h.p. sketch 

 (310) of the lining epithelium. 



(3) DUCTULI EFFERENTES. Study l.p. a stained section through 

 the efferent ductules of the epididymis. Sketch (311) a small 

 .area. Eelation of the ductuli efferentes to the coni vasculosi and to the 



