1094 



SUBMAMMALIAN VERTEBRATES 



TABLE 18.1 



The cellular composition during the different stages of the spermatogenic cycle of the drake 

 (From Y. Clermont, Arch. Anat. microscop. et Morphol. exper., 47, 47-66, 1958.) 



Spermatogonia, G 



Spermatogonia in mitosis, M 



Primary spermatocytes 



Interi)hase, I 



Leptotene, L 



Zygotene, Z 



Pachytene, P 



Diakenesis, D 



Metaphase, Sim 



Secondary spermatocj^tes, SII 



Dividing spermatocj^tes, Slim 



Spermitid. Spermiogene.sis steps, 1-10 



L, Z 



Stage of Cycle 



L, Z 



III IV V V 



P, D 



D, S, Im 



SII 



Slim 



Fig. 18.3. Schematic presentation of renewal of 

 spermatogonia in the drake (Clermont, 1958). A, 

 A' = stem cells, B, C — differentiated spermato- 

 gonia, S rrr spermatocytes. (From Y. Clermont, 

 Arch. Anat. microscop. et Morphol. exper., 47, 

 47-66, 1958.) 



(1959j, Fraps, Hooker and Forbes (1949) 

 detected progesterone in the blood of intact 

 roosters but not in the blood of capons, in- 

 dicating secretion of progesterone by testes 

 with presumably normal spermatogenetic 

 activity. Progesterone bioassays of the 

 blood of hypophysectomized roosters 

 treated with either avian luteinizing hor- 

 mone (LH) or follicle-stimulating hormone 

 (FSH) and with a combination of these 

 two hormones should reveal whether or not 



tul)ules are the source of progesterone in the 

 rooster. 



After the sperm are released into the 

 lumina of the seminiferous tubules they 

 have to pass through a duct system. The 

 latter has been described in detail by Lake 

 (1957). On leaving the seminiferous tubules 

 the sperm pass first through the tubuli recti, 

 structures characterized by the absence of 

 germinal epithelium and the presence of 

 Sertoli cells. These Sertoli cells apparently 

 secrete a lipoidal material into the lumen. 

 After passage through the tubuli recti the 

 sperm reach the rete testis which are lined 

 by a cuboidal or squamous epithelium. The 

 rete testis converges into the efferent ducts 

 which are convoluted and which form cone- 

 like structures comprising the head of the 

 epididymis. The ducts are lined by alter- 

 nating groups of tall and low cells with in- 

 tense holocrine secretion. The basement 

 membrane is surrounded by a circular 

 smooth muscle. The ductus epididymis, 

 which connects the efferent tubules to the 

 vas deferens, has a tall, pseudostratified, 

 columnar epithelium with nonmotile stereo- 

 cilia. The relationship between these duct 

 systems is illustrated in Figure 18.4. 



In the epididymis, which is quite small 

 compared with the epididymides of mam- 

 mals, sperm undergo a maturation process 

 which increases their fertilizing ability 



