. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. FIRST MATURATION D IVISION- SEGOND MATURATION DIVISION- ENTRANCE OF SPERM. Fig. 137. Maturation divisions of the oocyte relative to time of sperm entrance. (A) Sperm enters the primary oocyte before maturation divisions. In some, , Nereis, Thalassema, Ascaris, Platynereis, Myzostoma, etc., the sperm enters before the germinal vesicle breaks down; in Styela, Chaetopterus, pigeon, etc., the first maturation spindle is formed or forming; in the d
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. FIRST MATURATION D IVISION- SEGOND MATURATION DIVISION- ENTRANCE OF SPERM. Fig. 137. Maturation divisions of the oocyte relative to time of sperm entrance. (A) Sperm enters the primary oocyte before maturation divisions. In some, , Nereis, Thalassema, Ascaris, Platynereis, Myzostoma, etc., the sperm enters before the germinal vesicle breaks down; in Styela, Chaetopterus, pigeon, etc., the first maturation spindle is formed or forming; in the dog, the condition is somewhat similar to Nereis, Ascaris, etc. (B) Sperm enters the egg after first maturation division, , in secondary oocyte stage {Asterias (starfish), Amphioxus, hen, rabbit, man, frog, salamander, newt, most verte- brates). (C) Sperm enters the egg after maturation divisions are completed, , in the mature egg (Arbacia and other sea urchins; possibly in monotreme. Echidna, on occasion).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Nelsen, Olin E. (Olin Everett), b. 1898. New York, Blakiston
Size: 1033px × 2420px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, bookleafnumber295
