THE FEMALE The ovary of Proloplenis or Neoceratodus is long 

 and hangs down from the body wall as a band; the eggs are 

 shed from its lateral aspect. There is usually a distinct 

 epigonal extension. In Neoceratodus the ovary is bound ante- 

 riorly to the dorsal body wall (Figure 10-41 D); in Proloplenis 

 it is suspended by a short mesovarium. The convoluted Miil- 

 lerian duct lies lateral to the ovary; its slit-like fringed 

 ostium opens into the anterior end of the body cavity. Pos- 

 teriorly the duct has a straight expanded section, the uterus. 

 The two ducts unite to form a short median vagina which 

 enters the urogenital sinus through the tip of a papilla. 



The ovary in the dipnoan agrees with that of fishes but 

 differs from the sacciform ovary of the amphibian, where 

 the eggs are shed from all surfaces. 



Actinopterygians 

 Te/eosf 



THE MALE The testes of the teleost are long and rounded in 

 section; they extend nearly to the cloacal region. In texture 

 they are finely granular as opposed to the coarsely granular 

 or distinctly egg-laden ovary of the female. In fine structure 

 there is usually a central cavity into which radially arranged 

 short pouches (ampullae) or tubules open. The tubules may 

 join together as they e.xtend posteriorly, so that a central 

 cavity as such is not present. In syngnathids the testis is a 

 simple tube. 



The testis is not connected to kidney tubules, rather the 

 central canal, of whatever form it takes, extends po.steriorly 

 lateral to the swim bladder and urinary bladder (Figure 

 10-43). Eventually the ducts of either side join and open to 

 the outside between the anus and excretory openings. In the 

 cod the posterior ends of the testes are joined and a single 

 duct extends to the genital opening. In some fishes the more 

 posterior tubules of the testis are secretory and may be 

 identified as seminal vesicles (Weisel, 1949). 



The opening of the male genital sinus sometimes differs 

 from what has been described. It may open into the urinary 

 bladder as in muraenids and Anableps; into the excretory 

 sinus in blennies, the salmon, perch, and many others; into 

 the anal margin in Lota: and into the joined anal and ex- 

 cretory opening in syngnathids (i.e. into a cloaca). 



The oviduct can be of the endovarial variety (Figure 

 10-43 B), attached to the lateral aspect of the swim bladder 

 in front and the urinary bladder behind. Both swim and 

 urinary bladders are suspended in the medial septum. In 

 either position, body wall or down on the swim bladder, the 

 oviducts unite to form a genital sinus opening to the out- 

 side between anus and urinary apertures. In the cod the 

 two ovaries join posteriorly and utilize a single oviduct. Not 

 all females have saccular ovaries with oviducts. In the 

 salmon the ovary is a free band, or parovarial. The eggs pass 

 from the body cavity into a funnel lying above the rectum 

 and below the urinary bladder; this funnel opens between 

 the anus and excretory pore (Figure 10-44). The funnel is 

 formed by membranes extending out and upward from the 

 terminal part of the intestine to the body wall; the dorsal 

 mesentery of the gut is lacking in this region. In the 

 muraenids the ovary is a simple fold; the eggs form on 

 the lateral aspect and are shed into the coelom. Exit from 

 the body cavity is by bilateral slit-like openings behind the 

 anus. These openings are in the general position of the ab- 

 dominal pores of other fishes. 



Polypterui The male has an elongate testis closely con- 

 nected with the kidney (Figure 10-45). The central canal 

 begins anteriorly and in the thin posterior continuation 

 there is an interconnected set of channels. Posteriorly a single 

 duct emerges and, following the wall of the nephric duct, 

 opens in the urinary sinus. 



The male of Polypterus appears to be comparable to the 

 male teleost in having the central canal extended posteriorly 

 through the epigonal region, not to a separate pore, how- 

 ever, but to the cloaca. The posterior part of the male duct 

 has been assumed to have arisen in a parovarial style. 



The female has an elongate, band-like ovary hanging 

 down into the body cavity from its mesovarium (Figure 

 10-45 B). There are numerous ridges on the outer surface 

 from which the eggs are shed into the body cavity. The ovi- 

 duct lies lateral to the mesovarium, in the region of the pos- 

 terior half of the ovary. It follows the course of the nephric 

 duct to the posterior end of the body cavity, where it opens 

 into the urinary sinus almost where that sinus opens into 

 the cloaca. The oviduct is like that observed in the following 

 actinopterygians. 



THE FEMALE Ovaries in the teleosts are of two types: 

 simple bands hanging down into the body cavity, or sac- 

 cular. The latter are of two varieties: the parovarial is 

 formed by the free margin of the genital fold bending later- 

 ally and fusing with a fold from the body wall (Figure 

 1 0-42 A) ; the endovarial type is formed by the ventral margin 

 curling laterally to meet a fold from the upper margin of 

 the gonad (Figure 10-43). This folding of the genital ridge 

 is observed in the ovary of the salmon and in the region 

 posterior to the ovary where a separate oviduct is produced 

 in the salmon or Osmerus. 



Amia and Lepisosteui In males of A mm and Lepisosteus the 

 testis is long, band-like, and rounded at either end (Figure 

 10-46). It is attached by a broad mesorchium through which 

 numerous efferent ducts pass into the kidney. The nephric 

 duct shows no modification as a vas deferens. 



The ovary is suspended by a broad mesovarium in which 

 there are strands of tissue resembling the efferent ducts of the 

 male. The ovary of Amia differs markedly from that of 

 Lepisosteus in that it hangs free in the body cavity. From its 

 lateral, ridged surface the ova are shed into the body cavity 

 and carried to the cloaca through the large membranous 



THE REPRODUCTIVE SYSTEM 



329 



