. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 58 OVUM. received by the open fimbriated extremity of the Fallopian tube. The empty ovicapsule now undergoes a remarkable change by the deposit in its inte- rior of the substance termed corpus luteum, the quantity and nature of which vary greatly according as the escape of the ovule is fol- lowed or not by pregnancy. Of this change more will be said hereafter. The result in both cases is the ultimate closure and obliteration of the ovicapsules. In birds, scaly reptiles, and cartilaginous fishes, the greater size of the o
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 58 OVUM. received by the open fimbriated extremity of the Fallopian tube. The empty ovicapsule now undergoes a remarkable change by the deposit in its inte- rior of the substance termed corpus luteum, the quantity and nature of which vary greatly according as the escape of the ovule is fol- lowed or not by pregnancy. Of this change more will be said hereafter. The result in both cases is the ultimate closure and obliteration of the ovicapsules. In birds, scaly reptiles, and cartilaginous fishes, the greater size of the ovules when in a state of maturity is connected with a modi- Fig. 42. cr. Relation of the ova to the ovary in Birds. A. Ovary of a fowl, showing at aaa the most developed ova hanging from the ovary in their pedi- culated capsules; the non-vascular bands are seen on their most projecting sides; at bb, the empty capsules or calyces of ova that have been previously discharged; at c c, the more compact part near the root of the ovary, where the ova are less developed. B. Diagrammatic section of one of the most ad- vanced of the capsules; o, the extended ovarian substance forming the capsule; p, its pedicle; c, indicates in this and the preceding figure the most common position of the cicatricula or germ-disc and vesicle; o v, the two layers of the ovicapsule or ovisac, into which the blood-vessels penetrate: the dotted line v m, marks the vitelline membrane. fication of the structure of the ovary and the ovicapsules. Previous to the age for breeding, the ovary of birds — in which animals only one ovary and oviduct is usually developed or attains to functional activity — is a solid organ of a less firm texture than that of mammalia, and is adherent to the vertebral column in the mid- dle of the dorsal region. It contains at an earlier period a much greater number of ovi- capsules of a considerable size than are per- ceptible in mammalia. The stroma or ova- rian substance is in l
Size: 1141px × 2191px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
