FISHERY BULLETIN: VOL. 78, NO 2 



1977). The organs were preserved in 10% Forma- 

 lin'' (Mallinkrodt) solution and stored at the 

 Southwest Fisheries Center (SWFC), National 

 Marine Fisheries Service, NOAA, La Jolla, Calif. 

 At the time of capture, a variety of observations 

 were recorded, including identified pregnancy, 

 size of the fetus, and lactation. These data, dates 

 and location of capture as well as related pertinent 

 information, are recorded in logs at SWFC. Here 

 also the ovaries were sliced at 1 mm intervals, and 

 observations such as the presence of corpora lutea, 

 corpora albicantia, and ovarian size were recorded 

 and correlated with capture information. Those 

 apparently gravid uteri whose ovaries had a cor- 

 pus luteum were dissected further and, occasion- 

 ally, small fetuses were identified by SWFC staff. 

 In addition, the present authors carefully dissect- 

 ed three intact uteri of the 1977 catches where 

 ovaries contained corpora lutea but in which 

 pregnancy had not been recorded. 



For the purpose of the present study the repro- 

 ductive tracts of 53 nonpregnant dolphins, cap- 

 tured in 1976, and whose ovaries were recorded to 

 contain corpora lutea, were examined in detail. A 

 few specimens of 1975 and 1977 were also studied 

 and are included, bringing the figure to 58 genital 

 tracts. The tabulation of the reproductive condi- 

 tion of these tracts is showm in Table 1. 



These specimens represent the majority of re- 

 productive tracts recorded to possess unexplained 

 corpora lutea in 1976. There were 67 in all but not 

 all of the specimens were in suitable condition for 

 inclusion in this study. Thus, several were too 

 severely autolyzed for proper evaluation; in 

 others, either the complete ovaries or uteri could 

 not be located in the specimen collection. 



■•Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Table l. — Reproductive tracts of Steneila spp. studied because 

 corpora lutea were found in the absence of pregnancy or lacta- 

 tion. 



Species 



1975 



1976 



1977 



Stenella longirostris 

 S attenuate 



38 



15 



In an effort to better understand the macro- 

 scopic and histologic features of dolphins with 

 known reproductive events, it was desirable to 

 select suitable control material from the same 

 stored collection. Six groups of specimens were 

 selected for this purpose and consisted of the fol- 

 lowing specimens: Group I, 3 tracts of immature S. 

 longirostris; Group II, 6 tracts of mature female S. 

 longirostris having no corpus luteum and, there- 

 fore, termed "resting"; Group III, 12 tracts of S. 

 longirostris with early pregnancy, the embryos 

 measuring from 1 to 53 mm long (1-5 g with 

 placenta); Group IV, 6 tracts of later pregnant 

 dolphins (AS. longirostris and 2 S. attenuata) with 

 fetal sizes ranging from 300 to 725 mm; Group V, 

 11 tracts of lactating, nonpregnant females (10 S. 

 longirostris and 1 S. attenuata); Group VI, the 

 experimental group, 58 tracts of nonpregnant 

 females possessing a corpus luteum (38 S. lon- 

 girostris and 20 S. attenuata; Table 1); for a total of 

 96 female genital tracts. 



The gross examination of genital tracts by us 

 ascertained the following standard information: 

 Weight; length and width of uterine horns and 

 cervices; thickness of uterine walls at standard 

 locations. Histologic sections, stained with 

 hematoxylin and eosin, were prepared from stan- 

 dard locations of tubes, uterine horns, lower 

 uterine segments, and ovaries (Figure 1). Mea- 

 surements of uterine mucosa and muscularis were 

 made at low power microscopic examination with 

 the aid of a calibrated ocular micrometer. At his- 

 tologic examination the uterine findings (glands, 

 secretion, mitoses, edema, hyalinization, inflam- 

 mation) were compared with the ovarian activity. 

 Relevant photomicrographs were made with a 

 Zeiss Axiomat. 



RESULTS 

 Controls 

 Group I, Immature Females 



These three S. longirostris measured from 164 to 

 176 cm body length (Table 2) and possessed neither 



508 



