890 



OP GENERATION ACTION OF THE FEMALE. 



fore a persistent cell of a peculiar epithelial formation. When mature a 

 primordial ovum has a diameter of 200 /a, (and since // represents a micro- 

 millimetre or 0.0000032809 of an inch, 200 // would equal .00065618, or about 

 g-g^th of an inch), and is contained within a capsule termed the Graafian fol- 

 licle or ovisac. 1 In a large Graafian follicle we may distinguish a connective- 

 tissue investing membrane, which is composed of two layers, the tunica fib- 

 rosa (g, Fig. 309) and the tunica propria folliculi (h); the latter is lined on 

 its internal surface by stratified columnar epithelium (i), constituting the 

 epithelium of the follicle or membrana granulosa. The membrana granulosa 

 is collected around each ovum into a disk-like investment termed the dibits 

 proligerus (e, Fig. 309), and the remainder of the follicular cavity contains 

 a clear fluid, the liquor folliculi. The earliest rudiment of every ovum con- 

 sists of a simple cell with soft granular protoplasm uninclosed by a mem- 

 brane, a nucleus and a uucleolus. The protoplasm of the primordial cell is 

 termed the formative or principal yolk, since it alone undergoes segmenta- 



A, primordial egg of Man, from ;;n eight months' fcetus: B, primordial egg of Rabbit; C, primordial 

 follicle of a 1'igeon; D, a somewhat older follicle from a 1'igcoti, showing commencing formation of sec- 

 ondary yolk; E, blind end of the ovary of an Ascaris nigro venosa, showing germinal vesicle, germinal 

 spot, and in sonic instances, a Schron's granule in a dill'use mass of protoplasm ; F, egg [ Ascaris nig. 

 from about the middle of the ovary. 



G, an Ovum from the Graafian Follicle of a Rabbit, n, epithelium of the ovum, part of the discus 

 proligerus; b, radially striated zona pellucida; c, germinal vesicle; ( /, germinal spot . ; e, yolk. 



tion and development. The nucleus is termed the germinal vesicle (Vesic- 

 ula germinativa ) (c, Fig. 310; vg, Fig. 311), and the nucleolus, the germinal 

 spot (Macula germinativa) (d, Fig. 310; tg, Fig. 311). Whilst still within 



Trans!., 1872, vol. ii, p. IfiJ. Since tlion there h:ive nppc-:ired Kapif, Keiehert's Arcliiv, 

 187'2, p. Til:;, denyiiii^, and Koiniti, Sclinlt/e's Archiv, Bd. x, p '201, and Born, llei- 

 chcrt's Archiv, 1874, p. 118, corroborating Wiildcyer's histolinjical observations. 

 1 Barry, Researches in Embryology, 1st series, in Philos. Transact., 1838. 



