Oogenesis in adult prosimians.

INTRODUCTION It is widely accepted that oogenesis normally stops early in mammalian development (see Brambell, 1956; Franchi, Mandl & Zuckerman, 1962). Nevertheless, it has been claimed that mitotically active oogonia, and oocytes in early stages of meiotic prophase occur in mature specimens of Galago senegalensis (Gerard, 1920, 1932; Gerard & Herlant, 1953; Herlant, 1961; Petter-Rousseaux, 1962; Butler, 1964), G. crassicaudatus (Gerard & Herlant, 1953), G. demidoffi (Gerard, 1932; Gerard & Herlant, 1953; Petter-Rousseaux, 1962), Perodicticus potto (Gerard & Herlant, 1953), Loris tardigradus lydekkerianus (Rao, 1927; Brambell, 1930), and Daubentonia madagascariensis (PetterRousseaux & Bourliere, 1965). The latter is a lemuroid prosimian, while all the others are lorisoids (Hill, 1953). It has also been asserted that new germ cells are formed by direct transformation from the somatic cells of the ovarian germinal epithelium (Gerard, 1920, 1932; Rao, 1927; Gerard & Herlant, 1953). These claims are totally inconsistent with current ideas on ovarian development and a re-examination of ovaries from adult prosimians was undertaken to confirm or deny them.