de VLAMING: CONTROL OF REPRODUCTION IN CILLICHTHYS 



Table 1. — Criteria used for histologically staging testes 

 of Gillichthys mirabilis. 



Stage 



Histological characteristics of testes 



"Regressing testis." Seminiferous lobules characterized by 

 large numbers of pyknotic nests of degenerating cells (sper- 

 matozoa, spermatids, and spermatocytes); phagocytes observed 

 free within the lobu'les. 



"Quiescent testis." Seminiferous lobules smaH in diameter. 

 Germinal epithelium corfslsts of ortly spermatogonia. Lumen 

 of the lobules contain only fev^ residual spermatozoa, and 

 the sperm duct Is coHopsed. 



"Mitotic phase." Same as Stage I, wirh the exception that 

 mitotic figures are observed in the spermatogonia. 



"Meiotic phase or active spermatogenesis." Testicular lobules 

 larger than In Stages 1 and 2; germinal epithelium consists 

 of spermatogonia, spermatocytes, and spermatids. 



"Prespawning testis." Seminiferous lobules large and dis- 

 tended vi/ith sperm. Germlnol epithelium consists of relatively 

 few spermatogonia. 



"Postspawning testis." Seminiferous 'lobules small and con- 

 tain relatively few sperm; sperm duct expanded and containing 

 re'sidual sperm. 



Table 2. — Criteria used for histologically staging ovaries 

 of Gillichthys mirabilis. 



Stage 



Histologica'l characteristics of ovaries 



I "Regressing ovary." Atretic follicles predominate in fhe ovary. 



Only nonytolky oocytes and oogonia present. 



II "Quiescent phase or phase of oogonial proliferation." Ovary 



characterized by nonyolky oocytes with a basophilic cytoplasm, 

 ond a diameter of less tfian 75 /i. Granulosa not fully or- 

 ganized around the developing oocytes. 



III "Phase of active vltellogenesis." Ovary characterized by 

 developing yolky oocytes whose diameter is between 75 /i 

 and 640 m- Granulosa fully organized around the oocytes. 



IV "Prespawning condition." Ovary characterized by oocytes 

 whose diameter Is in excess of 640 fi. Yalk vesicles abundant. 



V "Postspawning condition." The ovary is wine-red In color; 



the tunica albuginea thick, highly vascularized, and folded. 

 Postovulatory follicles predominate in the ovary. The stroma 

 of fhe ovary opipears disorganized, yet highlly vascularized. 



whether two independent groups have been 

 drawn from the same population. 



RESULTS 



EFFECTS OF CONSTANT TEMPERATURE 



AND PHOTOPERIOD ON FISH WITH 



REGRESSING GONADS 



To examine the influence of low and high 

 temperature treatments at different photoperi- 

 ods on gonadal recrudescence, fish with regres- 

 sing testes (Stage 0) and ovaries (Stage I) were 

 collected in July 1967, Fish were exposed to 

 13°C, at a short (8L/T6D) or long (15L/9D) 

 photoperiod, or to 27 °C at a short photoperiod 

 (8L/16D). 



The effects of these treatments on testicular 

 and ovarian weights are summarized in Figure 1. 

 The testes (Stage 0) and ovaries (Stage I) of 

 all of the initial controls were regressing. After 

 57 days, testicular and ovarian weights increased 

 significantly (P < 0.01) at both photoperiods 

 at 13°C, and were also significantly greater 

 (P < 0.01) than those of fish from nature sacri- 

 ficed at the same time. Ovarian weights of fe- 

 males exposed to 8L/16D at 13°C were signifi- 

 cantly greater (P < 0.01) than those of fish 

 exposed to 15L/9D at the same temperature. 



Testes of all fish at 13°C were in the meiotic 

 phase of spermatogenesis (Stage 3) whereas 

 those of all fish in the September sample from 

 nature were only in Stage 2 (mitotic prolifer- 

 ation phase). The ovaries of all fish at 13°C 

 were in phases of vltellogenesis (Stage III); the 

 oocytes of fish at BL/IBD were, however, in a 



?60 

 1> 50 



r-,0 



f 30 

 2 20 



3 



y 



^ lO- 







r^ 



i^ 



<¥^ 



\h 



Initial 



Control 



(IS July) 



8L 8L I5L 

 27° 13° 



9 S«plember 



8L 

 27° 



27 Now 



2000- 

 1800- 

 1600 



i 1200 



* 1000 



c 



1 800 



> 



o 



600 



400 



200 







m ji= 



Initial 



Control 



Ui July) 



rfl 



8L BL I5L 

 27° 13° 



9 Seplennber 



Jl 



8L 

 27° 



27 Nov 



Figure 1.— Effect of 13°C at a long (15L/9D) 

 photoperiod and 13° and 27°C at a short (8L/ 

 16D) photoperiod on testicular and ovarian 

 weight in Gillichthys mirabilis. Mean gonadal 

 weight is illustrated by histograms; the mean 

 is bracketed by one standard error. Shaded 

 histograms represent gonadal weight of samples 

 collected in nature; open histograms, experi- 

 mental groups. Light (hours per 24 hr), tem- 

 perature, and dates on which fish were sacrificed 

 are recorded below the histograms. Sample 

 sizes are indicated atop each histogram. 



1139 



