Seasonal steroids variations and maturity stages in the female chub, Leuciscus cephalus L. (Pisces, Cyprinidae)

Figures & data

Table I. Mean total lengths (mm), body and gonadal mass (g) of the female chub Leuciscus cephalus by collection.

Month	n	Total length (mm)	Body mass (g)	Gonadal mass (g)
		Mean±SD	Mean±SD	Mean±SD
July 2004	17	179±20	85.60±0.10	0.51±0.05
September 2004	11	183±11	61.32±0.15	0.13±0.02
October 2004	20	201±15	58.03±0.26	0.11±0.05
November 2004	20	172±26	43.50±0.10	0.30±0.10
December 2004	17	185±31	47.05±0.25	0.40±0.05
January 2005	20	145±.40	44.27±0.10	0.38±0.15
February 2005	18	203±18	115.01±0.30	1.74±0.25
March 2005	19	144±33	58.90±0.10	0.90±0.28
April 2005	22	180±41	84.03±0.50	2.51±0.12
May 2005	20	185±51	88.66±0.60	3.15±0.05
June 2005	18	179±36	84.00±0.70	1.8±0.12

Table II. Maturity stages of ovaries of wild‐caught chub Leuciscus cephalus. Oocyte stage, appearance and oocyte diameter (mean±SD) detected monthly.

Ovary maturity stage	Oocyte type	Oocyte diameter (mm)
		Mean±SD
Immature	Oogonia	December, January	0.17±0.005
Maturing	Oogonia, previtellogenic and vitellogenic oocytes	February	0.31±0.012
		March	0.57±0.011
		April	1.04±0.140
Mature	Oogonia, previtellogenic and vitellogenic oocytes	May	1.14±0.120
		Jun	0.49±0.038
Post‐mature	Oogonia, previtellogenic oocytes and atretic follicles	July–November	0.50±0.030

Figure 1 Histological sections(A–D) of ovaries of the chub Leuciscus cephalus during A, undeveloped stage: immature (primitive oogonia, PO); B, early recovery of gonadal activity stage: maturing (early vitellogenic, EV); C, ripening stage: mature (vitellogenic, VO); D, resting stage: post‐mature (atretic, AT). Stained with hematoxylin and eosin. Scale bars: A–D = 50 µm and A'–D' = 100 µm.

Figure 2 Monthly changes ofφ = mean oocyte diameter and GSI = gonadosomatic index (A), plasma levels of E₂ = 17β‐estradiol (B); and A = androgen (C) in the chub Leuciscus cephalus. Each value represents the mean of three determinations in triplicate of each sample (n = 20)±SD. * Level of significance versus the mean values observed in the preceding month (P<0.05).