|
Ovarian stage |
Histological description |
Oocyte diameter*(μm) |
|
I – Immature/recovering
(previtellogenic stage) |
Thick ovarian wall with centrally located germanium surrounded by number of oocytes; cells are spherical or oval in shape and arranged at the periphery of oocytes; ovary consists of primary and secondary oocytes; follicle cells are surrounded by bigger oocytes |
30 – 90
(53 ± 9.2) |
| II – Developing (vitellogenic stage I) |
Oocytes consist of a band of yolk globules located peripherally with a prominent nucleus and nucleolus; oocytes are enveloped by follicle cells. |
90 – 120
(110 ± 8.8) |
| III – Mature
(vitellogenic stage II) |
Peripherally located yolk globules migrate towards the centre of oocytes. |
120 – 170
(162 ± 11.1) |
| IV – Ripe
(vitellogenic stage III) |
Large accumulation of yolk globules occupying the entire oocyte; disappearance of nucleus and nucleolus; fine inter dispersed protein globules in between the large lipid yolk globules; appearance of disintegrated follicle cells around oocytes. |
170 – 210
(198 ± 8.9) |
| V – Spent ovary |
Ovary shows several post-ovulatory follicles along with unextruted ova. Atretic oocytes also present. |
50 – 100
(71 ± 12) |
