fat body 



s organ 



ovarian tissue 



duct 



V B C 



Figure 1 0-39. Reproduction system of the toad (Bufo vulgaris). A, normal male toad; B, hermaphro- 

 ditic male; C, hermaphroditic female. (After van den Broek, 1 933) 



suit, single follicles are frequently larger than the entire in- 

 active ovary. The Miillerian ducts consist of five sections: 

 ostium, tube, isthmus, uterus and vagina. The ostium opens 

 anterior to the ovary and leads into the tube portion, which 

 is folded and pleated and loops anteriorly, then medially, 

 and then back. The tube tapers to the narrow third part, 

 the isthmus which leads into the thicker-walled uterus. The 

 terminal, thin-walled vagina, extends to the cloaca into 

 which it opens separately from that of the other side. The 

 urogenital part of the cloaca lies posterior to the gut open- 

 ing. This posterior portion, the urodeum, is produced by up- 

 ward and backward movement of the point of entrance of 

 excretory and reproductive ducts. 



The bird differs in that the right ovary is usually rudi- 

 mentary, the left producing all the ova. Paired ovaries are 

 present in only a few birds of prey. The right oviduct is also 

 vestigial. Vestigial deferent ducts are sometimes present in 

 the female. 



Amphibians 



The male The testis is a smoothly rounded mass in the 

 anuran (Figure 10-39), but in the salamander it may be elon- 

 gated (Figure 10-11), divided into two or more lobes, or even 

 separated into a longitudinal series of testicules as in the apo- 

 dan and salamander Desmognathus. In the development of 

 such strands of testicules, new units bud off toward the head; 

 one for each year in some species. 



In the bufonids (the toads), there is a Bidder's organ at 

 the anterior end of the testis, and in front of this a digiti- 



form (with finger like extensions) fat body. In the frogs 

 only the fat body is present. In salamanders and apodans 

 fat bodies occur medial to the gonad or ventral to the gonad. 

 The internal anatomy of the testis is like that of the reptile 

 but less complex. The short seminiferous tubes have a wide 

 lumen and end blindly; in some species they can be described 

 as ampullae. Several ampullae or tubules converge to a 

 ductus rectus, which in turn enters the central canal lying 

 along the line of the supporting mesentery. The efferent 

 ducts are of varying number and extend to the marginal 

 canal of the kidney. This canal is derived from outgrowths 

 from the capsules of the primary tubules of the anterior 

 part of the mesonephric kidney— but not the most ante- 

 rior part. The tubuli mesenephroi, or mesonephric tubules, 

 extend to the epididymidal duct. The efferent ducts develop 

 from the strands of mesonephric blastema left behind in the 

 separation of gonad and kidney. The kidney tubules carry- 

 ing sperm retain their glomeruli in the apodan and the 

 salamander Spelerpes but lose them in most amphibians. A 

 distinct epididymis is developed in Necturus but not in all 

 salamanders. The nephric duct may be quite thickened and 

 may enter the cloaca separately without an ampulla. A 

 Mullerian duct lies along the nephric duct in the male. 



The femo/e The ovary is an irregular, elongate mass in 

 which there is a single cavity (urodele) or many (10 to 30) 

 cavities (anuran). The eggs are not ruptured into the cen- 

 tral cavity of cavities but into the body cavity. The Mul- 

 lerian duct of the young female is not much larger than 

 that of the male. In the mature animal it becomes swollen 



THE REPRODUCTIVE SYSTEM • 325 



