FOLLICLE FORMATION IN GUINEA-PIGS AND RABBITS: A COMPARATIVE STUDY WITH NOTES ON THE RETE OVARII

A.R.C. Institute of Animal Physiology, Babraham, Cambridge (Received 3rd March 1975) At the end of the meiotic prophase, oocytes are enclosed by adjacent cells to form primordial follicles. Agreement is lacking on the origin of these cells, sometimes seen as epithelial, but in papers on man (Sauramo, 1954), the mouse (Peters & Pedersen, 1967), the rabbit (Peters et al., 1965) and the ferret (Deanesly, 1970) they have been clearly described as stromal cells which have ramified among the oocytes from the earliest stages of ovarian development. At first these cells are flattened but they become cuboid and their nuclei enlarge—a transition readily seen in the rabbit and ferret (see Deanesly, 1970: Figs 20 and 21). Recently, it has been suggested by Byskov & Lintern-Moore (1973) and Peters (1973) that the rete tubules within the mouse ovary contribute cells to the formation of follicles and differentiate into granulosa cells. For