Define vitellogenesis. During which phase of oogenesis does it occur?

Explanation

### Step-by-Step Text Solution:

1. **Definition of Vitellogenesis**:
Vitellogenesis is the process of yolk formation in the oocytes (egg cells) of lecithotropic organisms. This process involves the accumulation of nutrients, primarily proteins and lipids, which are stored in the form of yolk within the developing egg. The yolk serves as a source of energy and nutrients for the embryo after fertilization.

2. **Phase of Oogenesis**:
Vitellogenesis occurs during the oogenesis process, specifically during the meiotic prophase of the first meiotic division. Oogenesis is the process through which female gametes (ova) are produced, and it consists of several stages.

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