File:Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus (1953) (20049085793).jpg

Title: Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus
Identifier: comparativeembry00nels (find matches)
Year: 1953 (1950s)
Authors: Nelsen, Olin E. (Olin Everett), b. 1898
Subjects: Vertebrates -- Embryology; Comparative embryology
Publisher: New York, Blakiston
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ACTIVITIES OF THE OVARY 71 by Karl Ernst von Baer (1792-1876). The following statement is taken from de Graaf relative to egg follicles. We may assert confidently that eggs are found in all kinds of animals, since they may be observed not only in birds, in fishes, both oviparous and viviparous, but very clearly also in quadrupeds and even in man himself. Since it is known to everyone that eggs are found in birds and fishes, this needs no investigation; but also in rabbits, hares, dogs, swine, sheep, cows, and other animals which we have dissected, those structures similar to vesicles exhibit themselves to the eyes of the dissectors like the germs of eggs in birds. Occurring in the superficial parts of the testicles, they push up the common tunic, and sometimes shine through it, as if their exit from the testis is impending. (See fig. 48; also Corner, '43, page 128.) The mammalian egg with a single layer of epithelial cells surrounding it is known as a primary Graafian follicle (fig. 41B-D). As the egg and follicle grow, the number of epithelial cells increase and eventually there are several AND
Text Appearing After Image:
THECA EXTERNA DEVELOPING EGG THE CUMULUS OOPHORUS C. Fig. 43. Tertiary conditions of the Graafian follicle in the opossum ovary. Similar con- ditions are found in other mammalian ovaries. (A) Follicle in which the antral vacuoles are beginning to form. (B) This is a follicle in which the antral vacuoles are more numerous and are beginning to coalesce. (C) Condition of the Graafian follicle in the opossum ovary approaching maturity. Observe that the antral space is large and is filled with fluid, the liquor folliculi, while the egg and its surrounding cumulus cells are located at one end of the follicle. The thecal tissue around the follicle is well developed.

Note About Images